gormgen is a code generation tool to generate a better API to query and update gorm structs without having to deal with interface{}s or with database column names.

Note : gormgen is still is still in early development phase. It may contain bugs and the API is not yet stable. Your suggestions for improving gormgen are welcome through issues/PRs.

// Querying

// The gorm way:
users := []User{}
err := db.Where("age > ?", 20).Order("age ASC").Limit(10).Find(&users).Error

// gormgen way
users, err := (&UserQueryBuilder{}).
  WhereAge(gormgen.GreaterThanPredicate, 20).
  OrderByAge(true).
  Limit(10).
  QueryAll(db)


// Creating Object
user := &User{
  Name: "Bla",
  Age: 20,
}

// The gorm way
err := db.Create(user).Error

// The gormgen way
err := user.Save(db)

• No more ugly interface{}s when doing in the Where function. Using gormgen, the passed values will be type checked.
• No more ugly strings for column names for Where and Order functions. By this, you won't need to convert the field name to the column name yourself, gormgen will do it for you. Also, you won't forget to change a column name when you change the field name because your code won't compile until you fix it everywhere.
• Query results are returned in a more intuitive way instead of passing them as a param. Also the errors are returned the "Go" way instead of explicitly accessing them.
• It doesn't alter your struct, so it's still compatible with gorm and you can still use the gorm way whenever you want (or for missing features in gormgen).

If you have the following :

//go:generate gormgen -structs User -output user_gen.go
type User struct {
	ID   uint   `gorm:"primary_key"`
	Name string
	Age  int
}

Run go generate and gormgen will generate for you :

func (t *User) Save(db *gorm.DB) error {/* … */}
func (t *User) Delete(db *gorm.DB) error {/* … */}
type UserQueryBuilder struct {/* … */}
func (qb *UserQueryBuilder) Count(db *gorm.DB) (int, error) {/* … */}
func (qb *UserQueryBuilder) First(db *gorm.DB) (*User, error) {/* … */} // Sorted by primary key
func (qb *UserQueryBuilder) QueryOne(db *gorm.DB) (*User, error) {/* … */} // Sorted by the order specified
func (qb *UserQueryBuilder) QueryAll(db *gorm.DB) ([]User, error) {/* … */}
func (qb *UserQueryBuilder) Limit(limit int) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) Offset(offset int) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) WhereID(p gormgen.Predicate, value uint) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) OrderByID(asc bool) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) WhereName(p gormgen.Predicate, value string) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) OrderByName(asc bool) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) WhereAge(p gormgen.Predicate, value int) *UserQueryBuilder {/* … */}
func (qb *UserQueryBuilder) OrderByAge(asc bool) *UserQueryBuilder {/* … */}

For the actual generated code, check the examples folder.

• go get -u github.com/MohamedBassem/gormgen/...
• Add the //go:generate comment mentioned above anywhere in your code.
• Add go generate to your build steps.
• The generated code will depend on gorm and gormgen, so make sure to vendor both of them.

• Inferring database column name from gorm convention or gorm struct tag.
• Ignoring fields with gorm:"-".
• Support for anonymous structs (IMPORTANT for gorm.Model).
• Support for type aliases.
• Support for detecting and querying with primary key.
• Support for the embedded struct tag.

Your contributions and ideas are welcomed through issues and pull requests.

Note for development : Make sure to have gormgen in your path to be able to run the tests. Also, always run the tests with make test to regenerate the test structs.

The parser of this package is heavily inspired from the source code of https://godoc.org/golang.org/x/tools/cmd/stringer. That's where I learned how to parse and type check a go package.