Workflow & Configuration

gorm gen always produces two sets of code. They live in the same package, so you can keep interface-driven queries and model-based helpers side by side.

Query API generator

Give the CLI an interface and annotate the methods with SQL template comments. The generator expands those comments, binds parameters, and adds a context.Context parameter when it is missing.

• Works with the default generics output or the --typed=false flag.
• Keeps SQL next to the interface that describes it.
• Emits plain Go implementations with no reflection.

Field helper generator

Point the CLI at your model structs. The generator scans fields and relationships to build helper types.

• Predicate builders like generated.User.Name.Eq("alice").
• Update helpers for Set, SetExpr, Incr, and related calls.
• Association helpers for Create, CreateInBatch, Update, Unlink, and Delete.

Typical command

gorm gen -i ./internal/models -o ./internal/generated

Configuration basics

gorm gen works without configuration, but a package-level genconfig.Config lets you pick output paths, decide which interfaces or structs are included, and map custom helper types.

package examples

import (
  "database/sql"
  "gorm.io/cli/gorm/field"
  "gorm.io/cli/gorm/genconfig"
)

var _ = genconfig.Config{
  OutPath: "examples/output",

  // Map Go types to helper kinds
  FieldTypeMap: map[any]any{
    sql.NullTime{}: field.Time{},
  },

  // Map `gen:"name"` tags to helper kinds
  FieldNameMap: map[string]any{
    "json": JSON{}, // use a custom JSON helper where fields are tagged `gen:"json"`
  },

  // Narrow what gets generated (patterns or type literals)
  IncludeInterfaces: []any{"Query*", models.Query(nil)},
  IncludeStructs:    []any{"User", "Account*", models.User{}},
}

Adjust the OutPath to pick a target package and use the include lists to focus on the interfaces and structs you want the CLI to read.

JSON field mapping example

0. Declare configuration

package examples

import "gorm.io/cli/gorm/genconfig"

var _ = genconfig.Config{
  OutPath: "examples/output",
  FieldNameMap: map[string]any{
    "json": JSON{}, // map fields with `gen:"json"` to a custom helper
  },
}

1. Tag the model field

package models

type User struct {
  // ...
  Profile string `gen:"json"`
}

2. Define the helper

// JSON is a field helper for JSON columns that generates different SQL per dialect.
type JSON struct{ column clause.Column }

func (j JSON) WithColumn(name string) JSON {
  c := j.column
  c.Name = name
  return JSON{column: c}
}

func (j JSON) Equal(path string, value any) clause.Expression {
  return jsonEqualExpr{col: j.column, path: path, val: value}
}

type jsonEqualExpr struct {
  col  clause.Column
  path string
  val  any
}

func (e jsonEqualExpr) Build(builder clause.Builder) {
  if stmt, ok := builder.(*gorm.Statement); ok {
    switch stmt.Dialector.Name() {
    case "mysql":
      v, _ := json.Marshal(e.val)
      clause.Expr{SQL: "JSON_EXTRACT(?, ?) = CAST(? AS JSON)", Vars: []any{e.col, e.path, string(v)}}.Build(builder)
    case "sqlite":
      clause.Expr{SQL: "json_valid(?) AND json_extract(?, ?) = ?", Vars: []any{e.col, e.col, e.path, e.val}}.Build(builder)
    default:
      clause.Expr{SQL: "jsonb_extract_path_text(?, ?) = ?", Vars: []any{e.col, e.path[2:], e.val}}.Build(builder)
    }
  }
}

3. Use it in queries

// Generates dialect-specific JSON comparisons
got, err := gorm.G[models.User](db).
  Where(generated.User.Profile.Equal("$.vip", true)).
  Take(ctx)

Re-run gorm gen whenever you add new interfaces or structs or adjust configuration; only the affected output files change.