ent/doc/md/code-gen.md

id, title

id	title
code-gen	Introduction

Installation

ent comes with a codegen tool called entc. In order to install entc run the following command:

go get github.com/facebookincubator/ent/entc/cmd/entc

Initialize A New Schema

In order to generate one or more schema templates, run entc init as follows:

entc init User Pet

init will create the 2 schemas (user.go and pet.go) under the ent/schema directory. If the ent directory does not exist, it will create it as well. The convention is to have an ent directory under the root directory of the project.

Generate Assets

After adding a few fields and edges, you want to generate the assets for working with your entities. Run the following command:

entc generate ./ent/schema

You should note that goimports is required for the codegen, and it can be installed using:

go get -u golang.org/x/tools/cmd/goimports

The generate command generates the following assets for the schemas:

• Client and Tx objects used for interacting with the graph.
• CRUD builders for each schema type. See CRUD for more info.
• Entity object (Go struct) for each of the schema types.
• Package containing constants and predicates used for interacting with the builders.
• A migrate package for SQL dialects. See Migration for more info.

Code Generation Options

For more info about codegen options, run entc generate -h:

generate go code for the schema directory

Usage:
  entc generate [flags] path

Examples:
  entc generate ./ent/schema
  entc generate github.com/a8m/x

Flags:
      --header string         override codegen header
  -h, --help                  help for generate
      --idtype [int string]   type of the id field (default int)
      --storage strings       list of storage drivers to support (default [sql])
      --target string         target directory for codegen
      --template strings      external templates to execute

Storage Options

entc can generate assets for both SQL and Gremlin dialect. The default dialect is SQL.

External Templates

entc accepts external Go templates to execute. If the template name is already defined by entc, it will override the existing one. Otherwise, it will write the execution output to a file with the same name as the template.

Example of a custom template provides a Node API for GraphQL - Github.

Schema Description

In order to get a description of your graph schema, run:

entc describe ./ent/schema

An example for the output is as follows:

Pet:
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	| Field |  Type   | Unique | Optional | Nillable | Default | UpdateDefault | Immutable |       StructTag       | Validators |
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	| id    | int     | false  | false    | false    | false   | false         | false     | json:"id,omitempty"   |          0 |
	| name  | string  | false  | false    | false    | false   | false         | false     | json:"name,omitempty" |          0 |
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	+-------+------+---------+---------+----------+--------+----------+
	| Edge  | Type | Inverse | BackRef | Relation | Unique | Optional |
	+-------+------+---------+---------+----------+--------+----------+
	| owner | User | true    | pets    | M2O      | true   | true     |
	+-------+------+---------+---------+----------+--------+----------+
	
User:
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	| Field |  Type   | Unique | Optional | Nillable | Default | UpdateDefault | Immutable |       StructTag       | Validators |
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	| id    | int     | false  | false    | false    | false   | false         | false     | json:"id,omitempty"   |          0 |
	| age   | int     | false  | false    | false    | false   | false         | false     | json:"age,omitempty"  |          0 |
	| name  | string  | false  | false    | false    | false   | false         | false     | json:"name,omitempty" |          0 |
	+-------+---------+--------+----------+----------+---------+---------------+-----------+-----------------------+------------+
	+------+------+---------+---------+----------+--------+----------+
	| Edge | Type | Inverse | BackRef | Relation | Unique | Optional |
	+------+------+---------+---------+----------+--------+----------+
	| pets | Pet  | false   |         | O2M      | false  | true     |
	+------+------+---------+---------+----------+--------+----------+