Ent

Any ORM or library is supported in Kratos project for data accessing. Please refer to the examples for integration.

Ent is an easy-to-use ORM which developed by Facebook. Here is a brief guide to use this library.

Install Ent

  1. go install entgo.io/ent/cmd/ent@latest

Create Schema

  1. ent new User

This command will generate schema in project/ent/schema/ directory.

  1. // <project>/ent/schema/user.go
  3. package schema
  5. import "entgo.io/ent"
  7. // User holds the schema definition for the User entity.
  8. type User struct {
  9.     ent.Schema
  10. }
  12. // Fields of the User.
  13. func (User) Fields() []ent.Field {
  14.     return nil
  15. }
  17. // Edges of the User.
  18. func (User) Edges() []ent.Edge {
  19.     return nil
  20. }

Add two fields name、age to User table.

  1. package schema
  3. import (
  4.     "entgo.io/ent"
  5.     "entgo.io/ent/schema/field"
  6. )
  8. // Fields of the User.
  9. func (User) Fields() []ent.Field {
  10.     return []ent.Field{
  11.         field.Int("age").
  12.             Positive(),
  13.         field.String("name").
  14.             Default("unknown"),
  15.     }
  16. }

Run go generate:

  1. go generate ./ent
  2. # ent generate ./ent/schema

Create DB Connection Client

First, create a new ent.Client. We use SQLite3 here for demonstration.

  1. package main
  3. import (
  4.     "context"
  5.     "log"
  7.     "<project>/ent"
  9.     _ "github.com/mattn/go-sqlite3"
  10. )
  12. func main() {
  13.     client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
  14.     if err != nil {
  15.         log.Fatalf("failed opening connection to sqlite: %v", err)
  16.     }
  17.     defer client.Close()
  18.     // Run the auto migration tool.
  19.     if err := client.Schema.Create(context.Background()); err != nil {
  20.         log.Fatalf("failed creating schema resources: %v", err)
  21.     }
  22. }

To create a User in table.

  1. func CreateUser(ctx context.Context, client *ent.Client) (*ent.User, error) {
  2.     u, err := client.User.
  3.         Create().
  4.         SetAge(30).
  5.         SetName("a8m").
  6.         Save(ctx)
  7.     if err != nil {
  8.         return nil, fmt.Errorf("failed creating user: %v", err)
  9.     }
  10.     log.Println("user was created: ", u)
  11.     return u, nil
  12. }

References