squirrel.go

// Package squirrel provides a fluent SQL generator.
//
// See https://github.com/lann/squirrel for examples.
package squirrel

import (
	"database/sql"
	"fmt"

	"github.com/lann/builder"
)

// Sqlizer is the interface that wraps the ToSql method.
//
// ToSql returns a SQL representation of the Sqlizer, along with a slice of args
// as passed to e.g. database/sql.Exec. It can also return an error.
type Sqlizer interface {
	ToSql() (string, []interface{}, error)
}

// Execer is the interface that wraps the Exec method.
//
// Exec executes the given query as implemented by database/sql.Exec.
type Execer interface {
	Exec(query string, args ...interface{}) (sql.Result, error)
}

// Queryer is the interface that wraps the Query method.
//
// Query executes the given query as implemented by database/sql.Query.
type Queryer interface {
	Query(query string, args ...interface{}) (*sql.Rows, error)
}

// QueryRower is the interface that wraps the QueryRow method.
//
// QueryRow executes the given query as implemented by database/sql.QueryRow.
type QueryRower interface {
	QueryRow(query string, args ...interface{}) RowScanner
}

// BaseRunner groups the Execer and Queryer interfaces.
type BaseRunner interface {
	Execer
	Queryer
}

// Runner groups the Execer, Queryer, and QueryRower interfaces.
type Runner interface {
	Execer
	Queryer
	QueryRower
}

// DBRunner wraps sql.DB to implement Runner.
type dbRunner struct {
	*sql.DB
}

func (r *dbRunner) QueryRow(query string, args ...interface{}) RowScanner {
	return r.DB.QueryRow(query, args...)
}

type txRunner struct {
	*sql.Tx
}

func (r *txRunner) QueryRow(query string, args ...interface{}) RowScanner {
	return r.Tx.QueryRow(query, args...)
}

func setRunWith(b interface{}, baseRunner BaseRunner) interface{} {
	var runner Runner
	switch r := baseRunner.(type) {
	case Runner:
		runner = r
	case *sql.DB:
		runner = &dbRunner{r}
	case *sql.Tx:
		runner = &txRunner{r}
	}
	return builder.Set(b, "RunWith", runner)
}

// RunnerNotSet is returned by methods that need a Runner if it isn't set.
var RunnerNotSet = fmt.Errorf("cannot run; no Runner set (RunWith)")

// RunnerNotQueryRunner is returned by QueryRow if the RunWith value doesn't implement QueryRower.
var RunnerNotQueryRunner = fmt.Errorf("cannot QueryRow; Runner is not a QueryRower")

// ExecWith Execs the SQL returned by s with db.
func ExecWith(db Execer, s Sqlizer) (res sql.Result, err error) {
	query, args, err := s.ToSql()
	if err != nil {
		return
	}
	return db.Exec(query, args...)
}

// QueryWith Querys the SQL returned by s with db.
func QueryWith(db Queryer, s Sqlizer) (rows *sql.Rows, err error) {
	query, args, err := s.ToSql()
	if err != nil {
		return
	}
	return db.Query(query, args...)
}

// QueryRowWith QueryRows the SQL returned by s with db.
func QueryRowWith(db QueryRower, s Sqlizer) RowScanner {
	query, args, err := s.ToSql()
	return &Row{RowScanner: db.QueryRow(query, args...), err: err}
}