relspecgo/pkg/writers/bun

Bun Writer

Generates Go source files with Bun model definitions from database schema information.

Overview

The Bun Writer converts RelSpec's internal database model representation into Go source code with Bun struct definitions, complete with proper tags, relationships, and table configuration.

Features

• Generates Bun-compatible Go structs
• Creates proper bun struct tags
• Adds relationship fields
• Supports both single-file and multi-file output
• Maps SQL types to Go types
• Handles nullable fields with sql.Null* types
• Generates table aliases

Usage

Basic Example

package main

import (
    "git.warky.dev/wdevs/relspecgo/pkg/models"
    "git.warky.dev/wdevs/relspecgo/pkg/writers"
    "git.warky.dev/wdevs/relspecgo/pkg/writers/bun"
)

func main() {
    options := &writers.WriterOptions{
        OutputPath:  "models.go",
        PackageName: "models",
    }

    writer := bun.NewWriter(options)
    err := writer.WriteDatabase(db)
    if err != nil {
        panic(err)
    }
}

CLI Examples

# Generate Bun models from PostgreSQL database
relspec --input pgsql \
  --conn "postgres://localhost/mydb" \
  --output bun \
  --out-file models.go \
  --package models

# Convert GORM models to Bun
relspec --input gorm --in-file gorm_models.go --output bun --out-file bun_models.go

# Multi-file output
relspec --input json --in-file schema.json --output bun --out-file models/

Generated Code Example

package models

import (
    "time"
    "database/sql"
    "github.com/uptrace/bun"
)

type User struct {
    bun.BaseModel `bun:"table:users,alias:u"`

    ID        int64     `bun:"id,pk,autoincrement" json:"id"`
    Username  string    `bun:"username,notnull,unique" json:"username"`
    Email     string    `bun:"email,notnull" json:"email"`
    Bio       sql.NullString `bun:"bio" json:"bio,omitempty"`
    CreatedAt time.Time `bun:"created_at,notnull,default:now()" json:"created_at"`

    // Relationships
    Posts []*Post `bun:"rel:has-many,join:id=user_id" json:"posts,omitempty"`
}

type Post struct {
    bun.BaseModel `bun:"table:posts,alias:p"`

    ID      int64          `bun:"id,pk" json:"id"`
    UserID  int64          `bun:"user_id,notnull" json:"user_id"`
    Title   string         `bun:"title,notnull" json:"title"`
    Content sql.NullString `bun:"content" json:"content,omitempty"`

    // Belongs to
    User *User `bun:"rel:belongs-to,join:user_id=id" json:"user,omitempty"`
}

Supported Bun Tags

• table - Table name and alias
• column - Column name (auto-derived if not specified)
• pk - Primary key
• autoincrement - Auto-increment
• notnull - NOT NULL constraint
• unique - Unique constraint
• default - Default value
• rel - Relationship definition
• type - Explicit SQL type

Type Mapping

SQL Type	Go Type	Nullable Type
bigint	int64	sql.NullInt64
integer	int	sql.NullInt32
varchar, text	string	sql.NullString
boolean	bool	sql.NullBool
timestamp	time.Time	sql.NullTime
numeric	float64	sql.NullFloat64

Notes

• Model names are derived from table names (singularized, PascalCase)
• Table aliases are auto-generated from table names
• Multi-file mode: one file per table named sql_{schema}_{table}.go
• Generated code is auto-formatted
• JSON tags are automatically added