Merge pull request #8 from sunboyy/entrypoint

Add entrypoint to the program

codecov.yml

@@ -2,7 +2,7 @@ coverage:
   status:
     project:
       default:
-        target: 70%
+        target: 75%
         threshold: 5%
     patch:
       default:

internal/generator/generator.go

@@ -0,0 +1,75 @@
+package generator
+
+import (
+	"bytes"
+	"html/template"
+
+	"github.com/sunboyy/repogen/internal/code"
+	"github.com/sunboyy/repogen/internal/mongo"
+	"github.com/sunboyy/repogen/internal/spec"
+	"golang.org/x/tools/imports"
+)
+
+// GenerateRepository generates repository implementation from repository interface specification
+func GenerateRepository(packageName string, structModel code.Struct, interfaceName string,
+	methodSpecs []spec.MethodSpec) (string, error) {
+
+	repositoryGenerator := repositoryGenerator{
+		PackageName:   packageName,
+		StructModel:   structModel,
+		InterfaceName: interfaceName,
+		MethodSpecs:   methodSpecs,
+		Generator:     mongo.NewGenerator(structModel, interfaceName),
+	}
+
+	return repositoryGenerator.Generate()
+}
+
+type repositoryGenerator struct {
+	PackageName   string
+	StructModel   code.Struct
+	InterfaceName string
+	MethodSpecs   []spec.MethodSpec
+	Generator     mongo.RepositoryGenerator
+}
+
+func (g repositoryGenerator) Generate() (string, error) {
+	buffer := new(bytes.Buffer)
+	if err := g.generateBase(buffer); err != nil {
+		return "", err
+	}
+
+	if err := g.Generator.GenerateConstructor(buffer); err != nil {
+		return "", err
+	}
+
+	for _, method := range g.MethodSpecs {
+		if err := g.Generator.GenerateMethod(method, buffer); err != nil {
+			return "", err
+		}
+	}
+
+	formattedCode, err := imports.Process("", buffer.Bytes(), nil)
+	if err != nil {
+		return "", err
+	}
+
+	return string(formattedCode), nil
+}
+
+func (g repositoryGenerator) generateBase(buffer *bytes.Buffer) error {
+	tmpl, err := template.New("file_base").Parse(baseTemplate)
+	if err != nil {
+		return err
+	}
+
+	tmplData := baseTemplateData{
+		PackageName: g.PackageName,
+	}
+
+	if err := tmpl.Execute(buffer, tmplData); err != nil {
+		return err
+	}
+
+	return nil
+}

internal/generator/generator_test.go

@@ -0,0 +1,278 @@
+package generator_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/sunboyy/repogen/internal/code"
+	"github.com/sunboyy/repogen/internal/generator"
+	"github.com/sunboyy/repogen/internal/spec"
+)
+
+func TestGenerateMongoRepository(t *testing.T) {
+	userModel := code.Struct{
+		Name: "UserModel",
+		Fields: code.StructFields{
+			{
+				Name: "ID",
+				Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"},
+				Tags: map[string][]string{"bson": {"_id", "omitempty"}},
+			},
+			{
+				Name: "Username",
+				Type: code.SimpleType("string"),
+				Tags: map[string][]string{"bson": {"username"}},
+			},
+			{
+				Name: "Gender",
+				Type: code.SimpleType("Gender"),
+				Tags: map[string][]string{"bson": {"gender"}},
+			},
+			{
+				Name: "Age",
+				Type: code.SimpleType("int"),
+				Tags: map[string][]string{"bson": {"age"}},
+			},
+		},
+	}
+	methods := []spec.MethodSpec{
+		// test find: One mode
+		{
+			Name: "FindByID",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "id", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
+			},
+			Returns: []code.Type{code.PointerType{ContainedType: code.SimpleType("UserModel")}, code.SimpleType("error")},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeOne,
+				Query: spec.QuerySpec{
+					Predicates: []spec.Predicate{
+						{Field: "ID", Comparator: spec.ComparatorEqual},
+					},
+				},
+			},
+		},
+		// test find: Many mode, And operator, NOT and LessThan comparator
+		{
+			Name: "FindByGenderNotAndAgeLessThan",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "gender", Type: code.SimpleType("Gender")},
+				{Name: "age", Type: code.SimpleType("int")},
+			},
+			Returns: []code.Type{
+				code.PointerType{ContainedType: code.SimpleType("UserModel")},
+				code.SimpleType("error"),
+			},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeMany,
+				Query: spec.QuerySpec{
+					Operator: spec.OperatorAnd,
+					Predicates: []spec.Predicate{
+						{Field: "Gender", Comparator: spec.ComparatorNot},
+						{Field: "Age", Comparator: spec.ComparatorLessThan},
+					},
+				},
+			},
+		},
+		{
+			Name: "FindByAgeLessThanEqual",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "age", Type: code.SimpleType("int")},
+			},
+			Returns: []code.Type{
+				code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+				code.SimpleType("error"),
+			},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeMany,
+				Query: spec.QuerySpec{
+					Predicates: []spec.Predicate{
+						{Field: "Age", Comparator: spec.ComparatorLessThanEqual},
+					},
+				},
+			},
+		},
+		{
+			Name: "FindByAgeGreaterThan",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "age", Type: code.SimpleType("int")},
+			},
+			Returns: []code.Type{
+				code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+				code.SimpleType("error"),
+			},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeMany,
+				Query: spec.QuerySpec{
+					Predicates: []spec.Predicate{
+						{Field: "Age", Comparator: spec.ComparatorGreaterThan},
+					},
+				},
+			},
+		},
+		{
+			Name: "FindByAgeGreaterThanEqual",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "age", Type: code.SimpleType("int")},
+			},
+			Returns: []code.Type{
+				code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+				code.SimpleType("error"),
+			},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeMany,
+				Query: spec.QuerySpec{
+					Predicates: []spec.Predicate{
+						{Field: "Age", Comparator: spec.ComparatorGreaterThanEqual},
+					},
+				},
+			},
+		},
+		{
+			Name: "FindByGenderOrAge",
+			Params: []code.Param{
+				{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+				{Name: "gender", Type: code.SimpleType("Gender")},
+				{Name: "age", Type: code.SimpleType("int")},
+			},
+			Returns: []code.Type{
+				code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+				code.SimpleType("error"),
+			},
+			Operation: spec.FindOperation{
+				Mode: spec.QueryModeMany,
+				Query: spec.QuerySpec{
+					Operator: spec.OperatorOr,
+					Predicates: []spec.Predicate{
+						{Field: "Gender", Comparator: spec.ComparatorEqual},
+						{Field: "Age", Comparator: spec.ComparatorEqual},
+					},
+				},
+			},
+		},
+	}
+
+	code, err := generator.GenerateRepository("user", userModel, "UserRepository", methods)
+
+	if err != nil {
+		t.Error(err)
+	}
+	expectedCode := `// Code generated by repogen. DO NOT EDIT.
+package user
+
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+func NewUserRepository(collection *mongo.Collection) UserRepository {
+	return &UserRepositoryMongo{
+		collection: collection,
+	}
+}
+
+type UserRepositoryMongo struct {
+	collection *mongo.Collection
+}
+
+func (r *UserRepositoryMongo) FindByID(ctx context.Context, arg0 primitive.ObjectID) (*UserModel, error) {
+	var entity UserModel
+	if err := r.collection.FindOne(ctx, bson.M{
+		"_id": arg0,
+	}).Decode(&entity); err != nil {
+		return nil, err
+	}
+	return &entity, nil
+}
+
+func (r *UserRepositoryMongo) FindByGenderNotAndAgeLessThan(ctx context.Context, arg0 Gender, arg1 int) (*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"gender": bson.M{"$ne": arg0},
+		"age":    bson.M{"$lt": arg1},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+
+func (r *UserRepositoryMongo) FindByAgeLessThanEqual(ctx context.Context, arg0 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"age": bson.M{"$lte": arg0},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+
+func (r *UserRepositoryMongo) FindByAgeGreaterThan(ctx context.Context, arg0 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"age": bson.M{"$gt": arg0},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+
+func (r *UserRepositoryMongo) FindByAgeGreaterThanEqual(ctx context.Context, arg0 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"age": bson.M{"$gte": arg0},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+
+func (r *UserRepositoryMongo) FindByGenderOrAge(ctx context.Context, arg0 Gender, arg1 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"$or": []bson.M{
+			{"gender": arg0},
+			{"age": arg1},
+		},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+`
+	expectedCodeLines := strings.Split(expectedCode, "\n")
+	actualCodeLines := strings.Split(code, "\n")
+
+	for i, line := range expectedCodeLines {
+		if line != actualCodeLines[i] {
+			t.Errorf("On line %d\nExpected = %v\nActual = %v", i, line, actualCodeLines[i])
+		}
+	}
+}

internal/generator/templates.go

@@ -0,0 +1,9 @@
+package generator
+
+const baseTemplate = `// Code generated by repogen. DO NOT EDIT.
+package {{.PackageName}}
+`
+
+type baseTemplateData struct {
+	PackageName string
+}

internal/mongo/generator.go

@@ -4,76 +4,37 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io"
 	"text/template"
 
 	"github.com/sunboyy/repogen/internal/code"
 	"github.com/sunboyy/repogen/internal/spec"
-	"golang.org/x/tools/imports"
 )
 
-// GenerateMongoRepository generates mongodb repository
-func GenerateMongoRepository(packageName string, structModel code.Struct, intf code.Interface) (string, error) {
-	var methodSpecs []spec.MethodSpec
-	for _, method := range intf.Methods {
-		methodSpec, err := spec.ParseInterfaceMethod(structModel, method)
-		if err != nil {
-			return "", err
-		}
-		methodSpecs = append(methodSpecs, methodSpec)
-	}
-
-	generator := mongoRepositoryGenerator{
-		PackageName:   packageName,
+// NewGenerator creates a new instance of MongoDB repository generator
+func NewGenerator(structModel code.Struct, interfaceName string) RepositoryGenerator {
+	return RepositoryGenerator{
 		StructModel:   structModel,
-		InterfaceName: intf.Name,
-		MethodSpecs:   methodSpecs,
+		InterfaceName: interfaceName,
 	}
-
-	output, err := generator.Generate()
-	if err != nil {
-		return "", err
-	}
-
-	return output, nil
 }
 
-type mongoRepositoryGenerator struct {
-	PackageName   string
+// RepositoryGenerator provides repository constructor and method generation from provided specification
+type RepositoryGenerator struct {
 	StructModel   code.Struct
 	InterfaceName string
-	MethodSpecs   []spec.MethodSpec
 }
 
-func (g mongoRepositoryGenerator) Generate() (string, error) {
-	buffer := new(bytes.Buffer)
-	if err := g.generateBaseContent(buffer); err != nil {
-		return "", err
-	}
-
-	for _, method := range g.MethodSpecs {
-		if err := g.generateMethod(buffer, method); err != nil {
-			return "", err
-		}
-	}
-
-	newOutput, err := imports.Process("", buffer.Bytes(), nil)
-	if err != nil {
-		return "", err
-	}
-
-	return string(newOutput), nil
-}
-
-func (g mongoRepositoryGenerator) generateBaseContent(buffer *bytes.Buffer) error {
-	tmpl, err := template.New("mongo_repository_base").Parse(baseTemplate)
+// GenerateConstructor generates mongo repository struct implementation and constructor for the struct
+func (g RepositoryGenerator) GenerateConstructor(buffer io.Writer) error {
+	tmpl, err := template.New("mongo_repository_base").Parse(constructorTemplate)
 	if err != nil {
 		return err
 	}
 
-	tmplData := mongoBaseTemplateData{
-		PackageName:   g.PackageName,
-		InterfaceName: g.InterfaceName,
-		StructName:    g.structName(),
+	tmplData := mongoConstructorTemplateData{
+		InterfaceName:  g.InterfaceName,
+		ImplStructName: g.structName(),
 	}
 
 	if err := tmpl.Execute(buffer, tmplData); err != nil {
@@ -83,27 +44,28 @@ func (g mongoRepositoryGenerator) generateBaseContent(buffer *bytes.Buffer) erro
 	return nil
 }
 
-func (g mongoRepositoryGenerator) generateMethod(buffer *bytes.Buffer, method spec.MethodSpec) error {
+// GenerateMethod generates implementation of from provided method specification
+func (g RepositoryGenerator) GenerateMethod(methodSpec spec.MethodSpec, buffer io.Writer) error {
 	tmpl, err := template.New("mongo_repository_method").Parse(methodTemplate)
 	if err != nil {
 		return err
 	}
 
-	implementation, err := g.generateMethodImplementation(method)
+	implementation, err := g.generateMethodImplementation(methodSpec)
 	if err != nil {
 		return err
 	}
 
 	var paramTypes []code.Type
-	for _, param := range method.Params[1:] {
+	for _, param := range methodSpec.Params[1:] {
 		paramTypes = append(paramTypes, param.Type)
 	}
 
 	tmplData := mongoMethodTemplateData{
 		StructName:     g.structName(),
-		MethodName:     method.Name,
+		MethodName:     methodSpec.Name,
 		ParamTypes:     paramTypes,
-		ReturnTypes:    method.Returns,
+		ReturnTypes:    methodSpec.Returns,
 		Implementation: implementation,
 	}
 
@@ -114,7 +76,7 @@ func (g mongoRepositoryGenerator) generateMethod(buffer *bytes.Buffer, method sp
 	return nil
 }
 
-func (g mongoRepositoryGenerator) generateMethodImplementation(methodSpec spec.MethodSpec) (string, error) {
+func (g RepositoryGenerator) generateMethodImplementation(methodSpec spec.MethodSpec) (string, error) {
 	switch operation := methodSpec.Operation.(type) {
 	case spec.FindOperation:
 		return g.generateFindImplementation(operation)
@@ -123,7 +85,7 @@ func (g mongoRepositoryGenerator) generateMethodImplementation(methodSpec spec.M
 	return "", errors.New("method spec not supported")
 }
 
-func (g mongoRepositoryGenerator) generateFindImplementation(operation spec.FindOperation) (string, error) {
+func (g RepositoryGenerator) generateFindImplementation(operation spec.FindOperation) (string, error) {
 	buffer := new(bytes.Buffer)
 
 	var predicates []predicate
@@ -172,6 +134,6 @@ func (g mongoRepositoryGenerator) generateFindImplementation(operation spec.Find
 	return buffer.String(), nil
 }
 
-func (g mongoRepositoryGenerator) structName() string {
+func (g RepositoryGenerator) structName() string {
 	return g.InterfaceName + "Mongo"
 }

internal/mongo/generator_test.go

@@ -1,14 +1,36 @@
 package mongo_test
 
 import (
-	"strings"
+	"bytes"
 	"testing"
 
 	"github.com/sunboyy/repogen/internal/code"
 	"github.com/sunboyy/repogen/internal/mongo"
+	"github.com/sunboyy/repogen/internal/spec"
+	"github.com/sunboyy/repogen/internal/testutils"
 )
 
-func TestGenerateMongoRepository(t *testing.T) {
+const expectedConstructorResult = `
+import (
+	"context"
+
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+func NewUserRepository(collection *mongo.Collection) UserRepository {
+	return &UserRepositoryMongo{
+		collection: collection,
+	}
+}
+
+type UserRepositoryMongo struct {
+	collection *mongo.Collection
+}
+`
+
+func TestGenerateConstructor(t *testing.T) {
 	userModel := code.Struct{
 		Name: "UserModel",
 		Fields: code.StructFields{
@@ -34,158 +56,46 @@ func TestGenerateMongoRepository(t *testing.T) {
 			},
 		},
 	}
-	intf := code.Interface{
-		Name: "UserRepository",
-		Methods: []code.Method{
-			{
+	generator := mongo.NewGenerator(userModel, "UserRepository")
+	buffer := new(bytes.Buffer)
+
+	err := generator.GenerateConstructor(buffer)
+
+	if err != nil {
+		t.Error(err)
+	}
+	if err := testutils.ExpectMultiLineString(expectedConstructorResult, buffer.String()); err != nil {
+		t.Error(err)
+	}
+}
+
+type GenerateMethodTestCase struct {
+	Name         string
+	MethodSpec   spec.MethodSpec
+	ExpectedCode string
+}
+
+func TestGenerateMethod(t *testing.T) {
+	testTable := []GenerateMethodTestCase{
+		{
+			Name: "simple find one method",
+			MethodSpec: spec.MethodSpec{
 				Name: "FindByID",
 				Params: []code.Param{
 					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
 					{Name: "id", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
 				},
 				Returns: []code.Type{code.PointerType{ContainedType: code.SimpleType("UserModel")}, code.SimpleType("error")},
-			},
-			{
-				Name: "FindOneByUsername",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "username", Type: code.SimpleType("string")},
-				},
-				Returns: []code.Type{
-					code.PointerType{ContainedType: code.SimpleType("UserModel")},
-					code.SimpleType("error"),
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeOne,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorEqual, Field: "ID"},
+						},
+					},
 				},
 			},
-			{
-				Name: "FindByUsername",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "username", Type: code.SimpleType("string")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByIDAndUsername",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "id", Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"}},
-					{Name: "username", Type: code.SimpleType("string")},
-				},
-				Returns: []code.Type{
-					code.PointerType{ContainedType: code.SimpleType("UserModel")},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByGenderNot",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "gender", Type: code.SimpleType("Gender")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByAgeLessThan",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "age", Type: code.SimpleType("int")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByAgeLessThanEqual",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "age", Type: code.SimpleType("int")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByAgeGreaterThan",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "age", Type: code.SimpleType("int")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByAgeGreaterThanEqual",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "age", Type: code.SimpleType("int")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByGenderOrAgeLessThan",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "gender", Type: code.SimpleType("Gender")},
-					{Name: "age", Type: code.SimpleType("int")},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-			{
-				Name: "FindByGenderIn",
-				Params: []code.Param{
-					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
-					{Name: "gender", Type: code.ArrayType{ContainedType: code.SimpleType("Gender")}},
-				},
-				Returns: []code.Type{
-					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
-					code.SimpleType("error"),
-				},
-			},
-		},
-	}
-
-	code, err := mongo.GenerateMongoRepository("user", userModel, intf)
-
-	if err != nil {
-		t.Error(err)
-	}
-	expectedCode := `// Code generated by repogen. DO NOT EDIT.
-package user
-
-import (
-	"context"
-
-	"go.mongodb.org/mongo-driver/bson"
-	"go.mongodb.org/mongo-driver/bson/primitive"
-	"go.mongodb.org/mongo-driver/mongo"
-)
-
-func NewUserRepository(collection *mongo.Collection) UserRepository {
-	return &UserRepositoryMongo{
-		collection: collection,
-	}
-}
-
-type UserRepositoryMongo struct {
-	collection *mongo.Collection
-}
-
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByID(ctx context.Context, arg0 primitive.ObjectID) (*UserModel, error) {
 	var entity UserModel
 	if err := r.collection.FindOne(ctx, bson.M{
@@ -195,20 +105,33 @@ func (r *UserRepositoryMongo) FindByID(ctx context.Context, arg0 primitive.Objec
 	}
 	return &entity, nil
 }
-
-func (r *UserRepositoryMongo) FindOneByUsername(ctx context.Context, arg0 string) (*UserModel, error) {
-	var entity UserModel
-	if err := r.collection.FindOne(ctx, bson.M{
-		"username": arg0,
-	}).Decode(&entity); err != nil {
-		return nil, err
-	}
-	return &entity, nil
-}
-
-func (r *UserRepositoryMongo) FindByUsername(ctx context.Context, arg0 string) ([]*UserModel, error) {
+`,
+		},
+		{
+			Name: "simple find many method",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByGender",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "gender", Type: code.SimpleType("Gender")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorEqual, Field: "Gender"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
+func (r *UserRepositoryMongo) FindByGender(ctx context.Context, arg0 Gender) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
-		"username": arg0,
+		"gender": arg0,
 	})
 	if err != nil {
 		return nil, err
@@ -219,18 +142,114 @@ func (r *UserRepositoryMongo) FindByUsername(ctx context.Context, arg0 string) (
 	}
 	return entities, nil
 }
-
-func (r *UserRepositoryMongo) FindByIDAndUsername(ctx context.Context, arg0 primitive.ObjectID, arg1 string) (*UserModel, error) {
-	var entity UserModel
-	if err := r.collection.FindOne(ctx, bson.M{
-		"_id":      arg0,
-		"username": arg1,
-	}).Decode(&entity); err != nil {
+`,
+		},
+		{
+			Name: "find with And operator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByGenderAndAge",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "gender", Type: code.SimpleType("Gender")},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Operator: spec.OperatorAnd,
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorEqual, Field: "Gender"},
+							{Comparator: spec.ComparatorEqual, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
+func (r *UserRepositoryMongo) FindByGenderAndAge(ctx context.Context, arg0 Gender, arg1 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"gender": arg0,
+		"age": arg1,
+	})
+	if err != nil {
 		return nil, err
 	}
-	return &entity, nil
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
 }
-
+`,
+		},
+		{
+			Name: "find with Or operator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByGenderOrAge",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "gender", Type: code.SimpleType("Gender")},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Operator: spec.OperatorOr,
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorEqual, Field: "Gender"},
+							{Comparator: spec.ComparatorEqual, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
+func (r *UserRepositoryMongo) FindByGenderOrAge(ctx context.Context, arg0 Gender, arg1 int) ([]*UserModel, error) {
+	cursor, err := r.collection.Find(ctx, bson.M{
+		"$or": []bson.M{
+			{"gender": arg0},
+			{"age": arg1},
+		},
+	})
+	if err != nil {
+		return nil, err
+	}
+	var entities []*UserModel
+	if err := cursor.All(ctx, &entities); err != nil {
+		return nil, err
+	}
+	return entities, nil
+}
+`,
+		},
+		{
+			Name: "find with Not comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByGenderNot",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "gender", Type: code.SimpleType("Gender")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorNot, Field: "Gender"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByGenderNot(ctx context.Context, arg0 Gender) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"gender": bson.M{"$ne": arg0},
@@ -244,7 +263,30 @@ func (r *UserRepositoryMongo) FindByGenderNot(ctx context.Context, arg0 Gender)
 	}
 	return entities, nil
 }
-
+`,
+		},
+		{
+			Name: "find with LessThan comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByAgeLessThan",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorLessThan, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByAgeLessThan(ctx context.Context, arg0 int) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"age": bson.M{"$lt": arg0},
@@ -258,7 +300,30 @@ func (r *UserRepositoryMongo) FindByAgeLessThan(ctx context.Context, arg0 int) (
 	}
 	return entities, nil
 }
-
+`,
+		},
+		{
+			Name: "find with LessThanEqual comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByAgeLessThanEqual",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorLessThanEqual, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByAgeLessThanEqual(ctx context.Context, arg0 int) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"age": bson.M{"$lte": arg0},
@@ -272,7 +337,30 @@ func (r *UserRepositoryMongo) FindByAgeLessThanEqual(ctx context.Context, arg0 i
 	}
 	return entities, nil
 }
-
+`,
+		},
+		{
+			Name: "find with GreaterThan comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByAgeGreaterThan",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorGreaterThan, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByAgeGreaterThan(ctx context.Context, arg0 int) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"age": bson.M{"$gt": arg0},
@@ -286,7 +374,30 @@ func (r *UserRepositoryMongo) FindByAgeGreaterThan(ctx context.Context, arg0 int
 	}
 	return entities, nil
 }
-
+`,
+		},
+		{
+			Name: "find with GreaterThanEqual comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByAgeGreaterThanEqual",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "age", Type: code.SimpleType("int")},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorGreaterThanEqual, Field: "Age"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByAgeGreaterThanEqual(ctx context.Context, arg0 int) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"age": bson.M{"$gte": arg0},
@@ -300,24 +411,30 @@ func (r *UserRepositoryMongo) FindByAgeGreaterThanEqual(ctx context.Context, arg
 	}
 	return entities, nil
 }
-
-func (r *UserRepositoryMongo) FindByGenderOrAgeLessThan(ctx context.Context, arg0 Gender, arg1 int) ([]*UserModel, error) {
-	cursor, err := r.collection.Find(ctx, bson.M{
-		"$or": []bson.M{
-			{"gender": arg0},
-			{"age": bson.M{"$lt": arg1}},
+`,
 		},
-	})
-	if err != nil {
-		return nil, err
-	}
-	var entities []*UserModel
-	if err := cursor.All(ctx, &entities); err != nil {
-		return nil, err
-	}
-	return entities, nil
-}
-
+		{
+			Name: "find with In comparator",
+			MethodSpec: spec.MethodSpec{
+				Name: "FindByGenderIn",
+				Params: []code.Param{
+					{Name: "ctx", Type: code.ExternalType{PackageAlias: "context", Name: "Context"}},
+					{Name: "gender", Type: code.ArrayType{ContainedType: code.SimpleType("Gender")}},
+				},
+				Returns: []code.Type{
+					code.ArrayType{ContainedType: code.PointerType{ContainedType: code.SimpleType("UserModel")}},
+					code.SimpleType("error"),
+				},
+				Operation: spec.FindOperation{
+					Mode: spec.QueryModeMany,
+					Query: spec.QuerySpec{
+						Predicates: []spec.Predicate{
+							{Comparator: spec.ComparatorIn, Field: "Gender"},
+						},
+					},
+				},
+			},
+			ExpectedCode: `
 func (r *UserRepositoryMongo) FindByGenderIn(ctx context.Context, arg0 []Gender) ([]*UserModel, error) {
 	cursor, err := r.collection.Find(ctx, bson.M{
 		"gender": bson.M{"$in": arg0},
@@ -331,13 +448,47 @@ func (r *UserRepositoryMongo) FindByGenderIn(ctx context.Context, arg0 []Gender)
 	}
 	return entities, nil
 }
-`
-	expectedCodeLines := strings.Split(expectedCode, "\n")
-	actualCodeLines := strings.Split(code, "\n")
+`,
+		},
+	}
+	for _, testCase := range testTable {
+		t.Run(testCase.Name, func(t *testing.T) {
+			userModel := code.Struct{
+				Name: "UserModel",
+				Fields: code.StructFields{
+					{
+						Name: "ID",
+						Type: code.ExternalType{PackageAlias: "primitive", Name: "ObjectID"},
+						Tags: map[string][]string{"bson": {"_id", "omitempty"}},
+					},
+					{
+						Name: "Username",
+						Type: code.SimpleType("string"),
+						Tags: map[string][]string{"bson": {"username"}},
+					},
+					{
+						Name: "Gender",
+						Type: code.SimpleType("Gender"),
+						Tags: map[string][]string{"bson": {"gender"}},
+					},
+					{
+						Name: "Age",
+						Type: code.SimpleType("int"),
+						Tags: map[string][]string{"bson": {"age"}},
+					},
+				},
+			}
+			generator := mongo.NewGenerator(userModel, "UserRepository")
+			buffer := new(bytes.Buffer)
 
-	for i, line := range expectedCodeLines {
-		if line != actualCodeLines[i] {
-			t.Errorf("On line %d\nExpected = %v\nActual = %v", i, line, actualCodeLines[i])
-		}
+			err := generator.GenerateMethod(testCase.MethodSpec, buffer)
+
+			if err != nil {
+				t.Error(err)
+			}
+			if err := testutils.ExpectMultiLineString(testCase.ExpectedCode, buffer.String()); err != nil {
+				t.Error(err)
+			}
+		})
 	}
 }

internal/mongo/templates.go

@@ -7,9 +7,7 @@ import (
 	"github.com/sunboyy/repogen/internal/code"
 )
 
-const baseTemplate = `// Code generated by repogen. DO NOT EDIT.
-package {{.PackageName}}
-
+const constructorTemplate = `
 import (
 	"context"
 
@@ -19,20 +17,19 @@ import (
 )
 
 func New{{.InterfaceName}}(collection *mongo.Collection) {{.InterfaceName}} {
-	return &{{.StructName}}{
+	return &{{.ImplStructName}}{
 		collection: collection,
 	}
 }
 
-type {{.StructName}} struct {
+type {{.ImplStructName}} struct {
 	collection *mongo.Collection
 }
 `
 
-type mongoBaseTemplateData struct {
-	PackageName   string
-	InterfaceName string
-	StructName    string
+type mongoConstructorTemplateData struct {
+	InterfaceName  string
+	ImplStructName string
 }
 
 const methodTemplate = `

internal/testutils/multilines.go

@@ -0,0 +1,31 @@
+package testutils
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ExpectMultiLineString compares two multi-line strings and report the difference
+func ExpectMultiLineString(expected, actual string) error {
+	expectedLines := strings.Split(expected, "\n")
+	actualLines := strings.Split(actual, "\n")
+
+	numberOfComparableLines := len(expectedLines)
+	if len(actualLines) < numberOfComparableLines {
+		numberOfComparableLines = len(actualLines)
+	}
+
+	for i := 0; i < numberOfComparableLines; i++ {
+		if expectedLines[i] != actualLines[i] {
+			return fmt.Errorf("On line %d\nExpected: %v\nReceived: %v", i+1, expectedLines[i], actualLines[i])
+		}
+	}
+
+	if len(expectedLines) < len(actualLines) {
+		return fmt.Errorf("Unexpected lines:\n%s", strings.Join(actualLines[len(expectedLines):], "\n"))
+	} else if len(expectedLines) > len(actualLines) {
+		return fmt.Errorf("Missing lines:\n%s", strings.Join(expectedLines[len(actualLines):], "\n"))
+	}
+
+	return nil
+}

internal/testutils/multilines_test.go

@@ -0,0 +1,72 @@
+package testutils_test
+
+import (
+	"testing"
+
+	"github.com/sunboyy/repogen/internal/testutils"
+)
+
+func TestExpectMultiLineString(t *testing.T) {
+	t.Run("same string should return nil", func(t *testing.T) {
+		text := `  Hello world
+			this is a test text  `
+
+		err := testutils.ExpectMultiLineString(text, text)
+
+		if err != nil {
+			t.Errorf("Expected = <nil>\nReceived = %s", err.Error())
+		}
+	})
+
+	t.Run("different string with same number of lines", func(t *testing.T) {
+		expectedText := `  Hello world
+this is an expected text
+how are you?`
+		actualText := `  Hello world
+this is a real text
+How are you?`
+
+		err := testutils.ExpectMultiLineString(expectedText, actualText)
+
+		expectedError := "On line 2\nExpected: this is an expected text\nReceived: this is a real text"
+		if err == nil || err.Error() != expectedError {
+			t.Errorf("Expected = %s\nReceived = %s", expectedError, err.Error())
+		}
+	})
+
+	t.Run("expected text longer than actual text", func(t *testing.T) {
+		expectedText := `  Hello world
+this is an expected text
+how are you?
+I'm fine...
+Thank you...`
+		actualText := `  Hello world
+this is an expected text
+how are you?`
+
+		err := testutils.ExpectMultiLineString(expectedText, actualText)
+
+		expectedError := "Missing lines:\nI'm fine...\nThank you..."
+		if err == nil || err.Error() != expectedError {
+			t.Errorf("Expected = %s\nReceived = %s", expectedError, err.Error())
+		}
+	})
+
+	t.Run("actual text longer than expected text", func(t *testing.T) {
+		expectedText := `  Hello world
+this is an expected text
+how are you?`
+		actualText := `  Hello world
+this is an expected text
+how are you?
+I'm fine...
+Thank you...`
+
+		err := testutils.ExpectMultiLineString(expectedText, actualText)
+
+		expectedError := "Unexpected lines:\nI'm fine...\nThank you..."
+		if err == nil || err.Error() != expectedError {
+			t.Errorf("Expected = %s\nReceived = %s", expectedError, err.Error())
+		}
+	})
+}

main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+
+	"github.com/sunboyy/repogen/internal/code"
+	"github.com/sunboyy/repogen/internal/generator"
+	"github.com/sunboyy/repogen/internal/spec"
+)
+
+func main() {
+	sourcePtr := flag.String("src", "", "source file")
+	destPtr := flag.String("dest", "", "destination file")
+	modelPtr := flag.String("model", "", "model struct name")
+	repoPtr := flag.String("repo", "", "repository interface name")
+
+	flag.Parse()
+
+	if *sourcePtr == "" {
+		panic("-source flag required")
+	}
+	if *modelPtr == "" {
+		panic("-model flag required")
+	}
+	if *repoPtr == "" {
+		panic("-repo flag required")
+	}
+
+	dest := os.Stdout
+	if *destPtr != "" {
+		if err := os.MkdirAll(filepath.Dir(*destPtr), os.ModePerm); err != nil {
+			panic(err)
+		}
+		file, err := os.Create(*destPtr)
+		if err != nil {
+			panic(err)
+		}
+		defer file.Close()
+		dest = file
+	}
+
+	code, err := generateFromRequest(*sourcePtr, *modelPtr, *repoPtr)
+	if err != nil {
+		panic(err)
+	}
+
+	if _, err := dest.WriteString(code); err != nil {
+		panic(err)
+	}
+}
+
+func generateFromRequest(fileName, structModelName, repositoryInterfaceName string) (string, error) {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, fileName, nil, parser.ParseComments)
+	if err != nil {
+		panic(err)
+	}
+
+	file := code.ExtractComponents(f)
+
+	structModel, ok := file.Structs.ByName(structModelName)
+	if !ok {
+		return "", errors.New("struct model not found")
+	}
+
+	intf, ok := file.Interfaces.ByName(repositoryInterfaceName)
+	if !ok {
+		return "", errors.New("interface model not found")
+	}
+
+	var methodSpecs []spec.MethodSpec
+	for _, method := range intf.Methods {
+		methodSpec, err := spec.ParseInterfaceMethod(structModel, method)
+		if err != nil {
+			return "", err
+		}
+		methodSpecs = append(methodSpecs, methodSpec)
+	}
+
+	return generator.GenerateRepository(file.PackageName, structModel, intf.Name, methodSpecs)
+}