repogen/README.md
2021-02-06 18:05:47 +07:00

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# repogen
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Repogen is a code generator for database repository in Golang inspired by Spring Data JPA. (WIP)
## Features
Repogen is a library that generates MongoDB repository implementation from repository interface by using method name pattern.
- CRUD functionality
- Method signature validation
- Supports single-entity and multiple-entity operations
- Supports many comparison operators
## Getting Started
This getting started tutorial shows a simple example on how to use repogen. You can also see the working code inside `examples` directory for more information.
### Step 1: Download and install repogen
Run this command in your terminal to download and install repogen
```
$ go get github.com/sunboyy/repogen
```
### Step 2: Write a repository specification
Write repository specification as an interface in the same file as the model struct. There are 5 types of operations that are currently supported and are determined by the first word of the method name. Single-entity and multiple-entity modes are determined be the first return value. More complex queries can also be written.
```go
// You write this interface specification (comment is optional)
type UserRepository interface {
// InsertOne stores userModel into the database and returns inserted ID if insertion
// succeeds and returns error if insertion fails.
InsertOne(ctx context.Context, userModel *UserModel) (interface{}, error)
// FindByUsername queries user by username. If a user with specified username exists,
// the user will be returned. Otherwise, error will be returned.
FindByUsername(ctx context.Context, username string) (*UserModel, error)
// UpdateDisplayNameByID updates a user with the specified ID with a new display name.
// If there is a user matches the query, it will return true. Error will be returned
// only when error occurs while accessing the database.
UpdateDisplayNameByID(ctx context.Context, displayName string, id primitive.ObjectID) (bool, error)
// DeleteByCity deletes users that have `city` value match the parameter and returns
// the match count. The error will be returned only when error occurs while accessing
// the database. This is a MANY mode because the first return type is an integer.
DeleteByCity(ctx context.Context, city string) (int, error)
// CountByCity returns the number of rows that match the given city parameter. If an error occurs while
// accessing the database, error value will be returned.
CountByCity(ctx context.Context, city string) (int, error)
}
```
### Step 3: Run the repogen
Run this command to generate a repository implementation from the specification.
```
$ repogen -src=<src_file> -dest=<dest_file> -model=<model_struct> -repo=<repo_interface>
```
- `<src_file>` is the file that contains struct model and repository interface code
- `<dest_file>` is the destination path for the repository implementation to be generated
- `<model_struct>` is the name of the model struct for generating the repository
- `<repo_interface>` is the name of the repository interface to generate implementation from
For example:
```
$ repogen -src=examples/getting-started/user.go -dest=examples/getting-started/user_repo.go -model=UserModel -repo=UserRepository
```
You can also write the above command in the `go:generate` format inside Go files in order to generate the implementation when `go generate` command is executed.
## License
Licensed under [MIT](https://github.com/sunboyy/repogen/blob/main/LICENSE)