metadata.go

package qb

import (
	"errors"
	"fmt"
)

// MetaData creates a new MetaData object and returns it as a pointer
// TODO: Metadata should not use builder, it should only use dialect
func MetaData(dialect Dialect) *MetaDataElem {
	return &MetaDataElem{
		tables:  []TableElem{},
		mapper:  Mapper(dialect),
		dialect: dialect,
	}
}

// MetaDataElem is the container for database structs and tables
type MetaDataElem struct {
	tables  []TableElem
	mapper  MapperElem
	dialect Dialect
}

// Add retrieves the struct and converts it using mapper and appends to tables slice
func (m *MetaDataElem) Add(model interface{}) {
	table, err := m.mapper.ToTable(model)
	if err != nil {
		panic(err)
	}

	m.AddTable(table)
}

// AddTable appends table to tables slice
func (m *MetaDataElem) AddTable(table TableElem) {
	m.tables = append(m.tables, table)
}

// Table returns the metadata registered table object. It returns nil if table is not found
func (m *MetaDataElem) Table(name string) TableElem {
	for _, t := range m.tables {
		if t.Name == name {
			return t
		}
	}

	panic(fmt.Errorf("Table %s not found", name))
}

// Tables returns the current tables slice
func (m *MetaDataElem) Tables() []TableElem {
	return m.tables
}

// CreateAll creates all the tables added to metadata
func (m *MetaDataElem) CreateAll(engine *Engine) error {
	tx, err := engine.DB().Begin()
	if err != nil {
		return err
	}

	for _, t := range m.tables {
		_, err = tx.Exec(t.Create(m.dialect))
		if err != nil {
			return err
		}
	}

	err = tx.Commit()

	if len(m.tables) == 0 {
		return errors.New("Metadata is empty. You need to register tables by calling db.AddTable(model{})")
	}

	return err
}

// DropAll drops all the tables which is added to metadata
func (m *MetaDataElem) DropAll(engine *Engine) error {
	tx, err := engine.DB().Begin()
	if err != nil {
		return err
	}

	for i := len(m.tables) - 1; i >= 0; i-- {
		drop := m.tables[i].Drop(m.dialect)
		_, err = tx.Exec(drop)
		if err != nil {
			return err
		}
	}

	err = tx.Commit()

	if len(m.tables) == 0 {
		return errors.New("Metadata is empty")
	}
	return err
}