db/schema/builder.go

package schema

import (
	"github.com/samber/lo"

	"git.fsdpf.net/go/db"
)

type Builder struct {
	Connection *db.Connection // The database connection instance
	Grammar    IGrammar       // The schema grammar instance
}

func NewSchema(conn *db.Connection) *Builder {
	var grammar IGrammar

	switch conn.GetConfig().Driver {
	case "mysql":
		grammar = &MysqlGrammar{}
	case "sqlite3":
		grammar = &Sqlite3Grammar{}
	}

	return &Builder{
		Connection: conn,
		Grammar:    grammar,
	}
}

// 判断数据表是否存在
func (this *Builder) HasTable(table string) (bool, error) {
	query := this.Grammar.CompileTableExists()
	dbName := this.Connection.GetConfig().Database

	count := 0

	if _, err := this.Connection.Select(query, []any{table, dbName}, &count); err != nil || count == 0 {
		return false, err
	}

	return true, nil
}

// 判断表字段是个存在
func (this *Builder) HasColumns(table string, columns ...string) (bool, error) {
	if tColumns, err := this.GetColumnListing(table); err != nil {
		return false, err
	} else {
		for _, col := range columns {
			if !lo.Contains(tColumns, col) {
				return false, nil
			}
		}
	}
	return true, nil
}

// 判断数据库列是否存在
func (this *Builder) GetColumnListing(table string) (columns []string, err error) {
	query := this.Grammar.CompileColumnListing(table)
	dbName := this.Connection.GetConfig().Database

	items := []struct {
		ID   int    `db:"id"`
		Name string `db:"name"`
	}{}

	bindings := []any{table, dbName}

	if this.Connection.GetConfig().Driver == "sqlite3" {
		bindings = nil
	}

	if _, err := this.Connection.Select(query, bindings, &items); err != nil {
		return nil, err
	}

	for _, item := range items {
		columns = append(columns, item.Name)
	}

	return
}

// 修改表
func (this *Builder) Table(table string, cb func(*Blueprint)) error {
	bp := this.createBlueprint(table)
	cb(bp)
	return this.Build(bp)
}

// 创建表
func (this *Builder) Create(table string, cb func(*Blueprint)) error {
	bp := this.createBlueprint(table)
	bp.Create()
	cb(bp)
	return this.Build(bp)
}

// 修改表名
func (this *Builder) Rename(from, to string) error {
	bp := this.createBlueprint(from)
	bp.Rename(to)
	return this.Build(bp)
}

// 删除表
func (this *Builder) Drop(table string) error {
	bp := this.createBlueprint(table)
	bp.Drop()
	return this.Build(bp)
}

// 删除表, 先判断再删除
func (this *Builder) DropIfExists(table string) error {
	bp := this.createBlueprint(table)
	bp.DropIfExists()
	return this.Build(bp)
}

func (b *Builder) createBlueprint(table string) *Blueprint {
	return NewBlueprint(table)
}

// Build execute the blueprint to build / modify the table
func (this *Builder) Build(bp *Blueprint) error {
	return bp.Build(this.Connection, this.Grammar)
}