GORM

This package contains a set of utilities for famous GORM library. If used together they can significantly help you to enable persistency in your application.

Collection Operators

The package provides some helpers which are able to apply collection operators defined in query package to a GORM query.

Applying query.Filtering

...
// given that Person is a protobuf message and PersonORM is a corresponding GORM model
db, assoc, err = gorm.ApplyFiltering(ctx, db, filtering, &PersonORM{}, &Person{})
if err != nil {
    ...
}
// Join required associations(for nested field support)
db, err = gorm.JoinAssociations(ctx, db, assoc, &PersonORM{})
if err != nil {
    ...
}
var people []Person
db.Find(&people)
...

Applying query.Sorting

...
db, assoc, err = gorm.ApplySorting(ctx, db, sorting, &PersonORM{}, &Person{})
if err != nil {
    ...
}
// Join required associations(for nested field support)
db, err = gorm.JoinAssociations(ctx, db, assoc, &PersonORM{})
if err != nil {
    ...
}
var people []Person
db.Find(&people)
...

Applying query.Pagination

...
db = gorm.ApplyPagination(ctx, db, pagination, &PersonORM{}, &Person{})
if err != nil {
    ...
}
var people []Person
db.Find(&people)
...

Applying query.FieldSelection

...
db, err = gorm.ApplyFieldSelection(ctx, db, fields, &PersonORM{}, &Person{})
if err != nil {
    ...
}
var people []Person
db.Find(&people)
...

Applying everything

...
db, err = gorm.ApplyCollectionOperators(ctx, db, &PersonORM{}, &Person{}, filtering, sorting, pagination, fields)
if err != nil {
    ...
}
var people []Person
db.Find(&people)
...

Transaction Management

We provide transaction management by offering gorm.Transaction wrapper and gorm.UnaryServerInterceptor. The gorm.Transaction works as a singleton to prevent an application of creating more than one transaction instance per incoming request. The gorm.UnaryServerInterceptor performs management on transactions. Interceptor creates new transaction on each incoming request and commits it if request finishes without error, otherwise transaction is aborted. The created transaction is stored in context.Context and passed to the request handler as usual.

NOTE Client is responsible to call txn.Begin() to open transaction.

// add gorm interceptor to the chain
  server := grpc.NewServer(
    grpc.UnaryInterceptor(
      grpc_middleware.ChainUnaryServer( // middleware chain
        ...
        gorm.UnaryServerInterceptor(), // transaction management
        ...
      ),
    ),
  )

import (
	"github.com/infobloxopen/atlas-app-toolkit/gorm"
)

func (s *MyService) MyMethod(ctx context.Context, req *MyMethodRequest) (*MyMethodResponse, error) {
	// extract gorm transaction from context
	txn, ok := gorm.FromContext(ctx)
	if !ok {
		return panic("transaction is not opened") // don't panic in production!
	}
	// start transaction
	gormDB := txn.Begin()
	if err := gormDB.Error; err != nil {
		return nil, err
	}
	// do stuff with *gorm.DB
	return &MyMethodResponse{...}, nil
}

Migration version validation

The toolkit does not require any specific method for database provisioning and setup. However, if golang-migrate or the infobloxopen fork of it is used, a couple helper functions are provided here for verifying that the database version matches a required version without having to import the entire migration package.