package sqlx

import (

"database/sql"

"database/sql/driver"

"errors"

"fmt"

"io/ioutil"

"path/filepath"

"reflect"

"strings"

"sync"

"github.com/guregu/sqlx/reflectx"

)

// Although the NameMapper is convenient, in practice it should not

// be relied on except for application code. If you are writing a library

// that uses sqlx, you should be aware that the name mappings you expect

// can be overridden by your user's application.

// NameMapper is used to map column names to struct field names. By default,

// it uses strings.ToLower to lowercase struct field names. It can be set

// to whatever you want, but it is encouraged to be set before sqlx is used

// as name-to-field mappings are cached after first use on a type.

var NameMapper = strings.ToLower

var origMapper = reflect.ValueOf(NameMapper)

// Rather than creating on init, this is created when necessary so that

// importers have time to customize the NameMapper.

var mpr *reflectx.Mapper

// mprMu protects mpr.

var mprMu sync.Mutex

// mapper returns a valid mapper using the configured NameMapper func.

func mapper() *reflectx.Mapper {

mprMu.Lock()

defer mprMu.Unlock()

if mpr == nil {

mpr = reflectx.NewMapperFunc("db", NameMapper)

} else if origMapper != reflect.ValueOf(NameMapper) {

// if NameMapper has changed, create a new mapper

mpr = reflectx.NewMapperFunc("db", NameMapper)

origMapper = reflect.ValueOf(NameMapper)

}

return mpr

}

// isScannable takes the reflect.Type and the actual dest value and returns

// whether or not it's Scannable. Something is scannable if:

// * it is not a struct

// * it implements sql.Scanner

// * it has no exported fields

func isScannable(t reflect.Type) bool {

if reflect.PtrTo(t).Implements(_scannerInterface) {

return true

}

if t.Kind() != reflect.Struct {

return true

}

// it's not important that we use the right mapper for this particular object,

// we're only concerned on how many exported fields this struct has

return len(mapper().TypeMap(t).Index) == 0

}

// ColScanner is an interface used by MapScan and SliceScan

type ColScanner interface {

Columns() ([]string, error)

Scan(dest ...interface{}) error

Err() error

}

// Queryer is an interface used by Get and Select

type Queryer interface {

Query(query string, args ...interface{}) (*sql.Rows, error)

Queryx(query string, args ...interface{}) (*Rows, error)

QueryRowx(query string, args ...interface{}) *Row

}

// Execer is an interface used by MustExec and LoadFile

type Execer interface {

Exec(query string, args ...interface{}) (sql.Result, error)

}

// Binder is an interface for something which can bind queries (Tx, DB)

type binder interface {

DriverName() string

Rebind(string) string

BindNamed(string, interface{}) (string, []interface{}, error)

}

// Ext is a union interface which can bind, query, and exec, used by

// NamedQuery and NamedExec.

type Ext interface {

binder

Queryer

Execer

}

// Preparer is an interface used by Preparex.

type Preparer interface {

Prepare(query string) (*sql.Stmt, error)

}

// determine if any of our extensions are unsafe

func isUnsafe(i interface{}) bool {

switch v := i.(type) {

case Row:

return v.unsafe

case *Row:

return v.unsafe

case Rows:

return v.unsafe

case *Rows:

return v.unsafe

case NamedStmt:

return v.Stmt.unsafe

case *NamedStmt:

return v.Stmt.unsafe

case Stmt:

return v.unsafe

case *Stmt:

return v.unsafe

case qStmt:

return v.unsafe

case *qStmt:

return v.unsafe

case DB:

return v.unsafe

case *DB:

return v.unsafe

case Tx:

return v.unsafe

case *Tx:

return v.unsafe

case sql.Rows, *sql.Rows:

return false

default:

return false

}

}

func mapperFor(i interface{}) *reflectx.Mapper {

switch i := i.(type) {

case DB:

return i.Mapper

case *DB:

return i.Mapper

case Tx:

return i.Mapper

case *Tx:

return i.Mapper

default:

return mapper()

}

}

var _scannerInterface = reflect.TypeOf((*sql.Scanner)(nil)).Elem()

var _valuerInterface = reflect.TypeOf((*driver.Valuer)(nil)).Elem()

// Row is a reimplementation of sql.Row in order to gain access to the underlying

// sql.Rows.Columns() data, necessary for StructScan.

type Row struct {

err error

unsafe bool

rows *sql.Rows

Mapper *reflectx.Mapper

}

// Scan is a fixed implementation of sql.Row.Scan, which does not discard the

// underlying error from the internal rows object if it exists.

func (r *Row) Scan(dest ...interface{}) error {

if r.err != nil {

return r.err

}

// TODO(bradfitz): for now we need to defensively clone all

// []byte that the driver returned (not permitting

// *RawBytes in Rows.Scan), since we're about to close

// the Rows in our defer, when we return from this function.

// the contract with the driver.Next(...) interface is that it

// can return slices into read-only temporary memory that's

// only valid until the next Scan/Close. But the TODO is that

// for a lot of drivers, this copy will be unnecessary. We

// should provide an optional interface for drivers to

// implement to say, "don't worry, the []bytes that I return

// from Next will not be modified again." (for instance, if

// they were obtained from the network anyway) But for now we

// don't care.

defer r.rows.Close()

for _, dp := range dest {

if _, ok := dp.(*sql.RawBytes); ok {

return errors.New("sql: RawBytes isn't allowed on Row.Scan")

}

}

if !r.rows.Next() {

if err := r.rows.Err(); err != nil {

return err

}

return sql.ErrNoRows

}

err := r.rows.Scan(dest...)

if err != nil {

return err

}

// Make sure the query can be processed to completion with no errors.

if err := r.rows.Close(); err != nil {

return err

}

return nil

}

// Columns returns the underlying sql.Rows.Columns(), or the deferred error usually

// returned by Row.Scan()

func (r *Row) Columns() ([]string, error) {

if r.err != nil {

return []string{}, r.err

}

return r.rows.Columns()

}

// ColumnTypes returns the underlying sql.Rows.ColumnTypes(), or the deferred error

func (r *Row) ColumnTypes() ([]*sql.ColumnType, error) {

if r.err != nil {

return []*sql.ColumnType{}, r.err

}

return r.rows.ColumnTypes()

}

// Err returns the error encountered while scanning.

func (r *Row) Err() error {

return r.err

}

// DB is a wrapper around sql.DB which keeps track of the driverName upon Open,

// used mostly to automatically bind named queries using the right bindvars.

type DB struct {

*sql.DB

driverName string

unsafe bool

Mapper *reflectx.Mapper

}

// NewDb returns a new sqlx DB wrapper for a pre-existing *sql.DB. The

// driverName of the original database is required for named query support.

func NewDb(db *sql.DB, driverName string) *DB {

return &DB{DB: db, driverName: driverName, Mapper: mapper()}

}

// DriverName returns the driverName passed to the Open function for this DB.

func (db *DB) DriverName() string {

return db.driverName

}

// Open is the same as sql.Open, but returns an *sqlx.DB instead.

func Open(driverName, dataSourceName string) (*DB, error) {

db, err := sql.Open(driverName, dataSourceName)

if err != nil {

return nil, err

}

return &DB{DB: db, driverName: driverName, Mapper: mapper()}, err

}

// MustOpen is the same as sql.Open, but returns an *sqlx.DB instead and panics on error.

func MustOpen(driverName, dataSourceName string) *DB {

db, err := Open(driverName, dataSourceName)

if err != nil {

panic(err)

}

return db

}

// MapperFunc sets a new mapper for this db using the default sqlx struct tag

// and the provided mapper function.

func (db *DB) MapperFunc(mf func(string) string) {

db.Mapper = reflectx.NewMapperFunc("db", mf)

}

// Rebind transforms a query from QUESTION to the DB driver's bindvar type.

func (db *DB) Rebind(query string) string {

return Rebind(BindType(db.driverName), query)

}

// Unsafe returns a version of DB which will silently succeed to scan when

// columns in the SQL result have no fields in the destination struct.

// sqlx.Stmt and sqlx.Tx which are created from this DB will inherit its

// safety behavior.

func (db *DB) Unsafe() *DB {

return &DB{DB: db.DB, driverName: db.driverName, unsafe: true, Mapper: db.Mapper}

}

// BindNamed binds a query using the DB driver's bindvar type.

func (db *DB) BindNamed(query string, arg interface{}) (string, []interface{}, error) {

return bindNamedMapper(BindType(db.driverName), query, arg, db.Mapper)

}

// NamedQuery using this DB.

// Any named placeholder parameters are replaced with fields from arg.

func (db *DB) NamedQuery(query string, arg interface{}) (*Rows, error) {

return NamedQuery(db, query, arg)

}

// NamedExec using this DB.

// Any named placeholder parameters are replaced with fields from arg.

func (db *DB) NamedExec(query string, arg interface{}) (sql.Result, error) {

return NamedExec(db, query, arg)

}

// Select using this DB.

// Any placeholder parameters are replaced with supplied args.

func (db *DB) Select(dest interface{}, query string, args ...interface{}) error {

return Select(db, dest, query, args...)

}

// Get using this DB.

// Any placeholder parameters are replaced with supplied args.

// An error is returned if the result set is empty.

func (db *DB) Get(dest interface{}, query string, args ...interface{}) error {

return Get(db, dest, query, args...)

}

// MustBegin starts a transaction, and panics on error. Returns an *sqlx.Tx instead

// of an *sql.Tx.

func (db *DB) MustBegin() *Tx {

tx, err := db.Beginx()

if err != nil {

panic(err)

}

return tx

}

// Beginx begins a transaction and returns an *sqlx.Tx instead of an *sql.Tx.

func (db *DB) Beginx() (*Tx, error) {

tx, err := db.DB.Begin()

if err != nil {

return nil, err

}

return &Tx{Tx: tx, driverName: db.driverName, unsafe: db.unsafe, Mapper: db.Mapper}, err

}

// Queryx queries the database and returns an *sqlx.Rows.

// Any placeholder parameters are replaced with supplied args.

func (db *DB) Queryx(query string, args ...interface{}) (*Rows, error) {

r, err := db.DB.Query(query, args...)

if err != nil {

return nil, err

}

return &Rows{Rows: r, unsafe: db.unsafe, Mapper: db.Mapper}, err

}

// QueryRowx queries the database and returns an *sqlx.Row.

// Any placeholder parameters are replaced with supplied args.

func (db *DB) QueryRowx(query string, args ...interface{}) *Row {

rows, err := db.DB.Query(query, args...)

return &Row{rows: rows, err: err, unsafe: db.unsafe, Mapper: db.Mapper}

}

// MustExec (panic) runs MustExec using this database.

// Any placeholder parameters are replaced with supplied args.

func (db *DB) MustExec(query string, args ...interface{}) sql.Result {

return MustExec(db, query, args...)

}

// Preparex returns an sqlx.Stmt instead of a sql.Stmt

func (db *DB) Preparex(query string) (*Stmt, error) {

return Preparex(db, query)

}

// PrepareNamed returns an sqlx.NamedStmt

func (db *DB) PrepareNamed(query string) (*NamedStmt, error) {

return prepareNamed(db, query)

}

// Conn is a wrapper around sql.Conn with extra functionality

type Conn struct {

*sql.Conn

driverName string

unsafe bool

Mapper *reflectx.Mapper

}

// Tx is an sqlx wrapper around sql.Tx with extra functionality

type Tx struct {

*sql.Tx

driverName string

unsafe bool

Mapper *reflectx.Mapper

}

// DriverName returns the driverName used by the DB which began this transaction.

func (tx *Tx) DriverName() string {

return tx.driverName

}

// Rebind a query within a transaction's bindvar type.

func (tx *Tx) Rebind(query string) string {

return Rebind(BindType(tx.driverName), query)

}

// Unsafe returns a version of Tx which will silently succeed to scan when

// columns in the SQL result have no fields in the destination struct.

func (tx *Tx) Unsafe() *Tx {

return &Tx{Tx: tx.Tx, driverName: tx.driverName, unsafe: true, Mapper: tx.Mapper}

}

// BindNamed binds a query within a transaction's bindvar type.

func (tx *Tx) BindNamed(query string, arg interface{}) (string, []interface{}, error) {

return bindNamedMapper(BindType(tx.driverName), query, arg, tx.Mapper)

}

// NamedQuery within a transaction.

// Any named placeholder parameters are replaced with fields from arg.

func (tx *Tx) NamedQuery(query string, arg interface{}) (*Rows, error) {

return NamedQuery(tx, query, arg)

}

// NamedExec a named query within a transaction.

// Any named placeholder parameters are replaced with fields from arg.

func (tx *Tx) NamedExec(query string, arg interface{}) (sql.Result, error) {

return NamedExec(tx, query, arg)

}

// Select within a transaction.

// Any placeholder parameters are replaced with supplied args.

func (tx *Tx) Select(dest interface{}, query string, args ...interface{}) error {

return Select(tx, dest, query, args...)

}

// Queryx within a transaction.

// Any placeholder parameters are replaced with supplied args.

func (tx *Tx) Queryx(query string, args ...interface{}) (*Rows, error) {

r, err := tx.Tx.Query(query, args...)

if err != nil {

return nil, err

}

return &Rows{Rows: r, unsafe: tx.unsafe, Mapper: tx.Mapper}, err

}

// QueryRowx within a transaction.

// Any placeholder parameters are replaced with supplied args.

func (tx *Tx) QueryRowx(query string, args ...interface{}) *Row {

rows, err := tx.Tx.Query(query, args...)

return &Row{rows: rows, err: err, unsafe: tx.unsafe, Mapper: tx.Mapper}

}

// Get within a transaction.

// Any placeholder parameters are replaced with supplied args.

// An error is returned if the result set is empty.

func (tx *Tx) Get(dest interface{}, query string, args ...interface{}) error {

return Get(tx, dest, query, args...)

}

// MustExec runs MustExec within a transaction.

// Any placeholder parameters are replaced with supplied args.

func (tx *Tx) MustExec(query string, args ...interface{}) sql.Result {

return MustExec(tx, query, args...)

}

// Preparex a statement within a transaction.

func (tx *Tx) Preparex(query string) (*Stmt, error) {

return Preparex(tx, query)

}

// Stmtx returns a version of the prepared statement which runs within a transaction. Provided

// stmt can be either *sql.Stmt or *sqlx.Stmt.

func (tx *Tx) Stmtx(stmt interface{}) *Stmt {

var s *sql.Stmt

switch v := stmt.(type) {

case Stmt:

s = v.Stmt

case *Stmt:

s = v.Stmt

case *sql.Stmt:

s = v

default:

panic(fmt.Sprintf("non-statement type %v passed to Stmtx", reflect.ValueOf(stmt).Type()))

}

return &Stmt{Stmt: tx.Stmt(s), Mapper: tx.Mapper}

}

// NamedStmt returns a version of the prepared statement which runs within a transaction.

func (tx *Tx) NamedStmt(stmt *NamedStmt) *NamedStmt {

return &NamedStmt{

QueryString: stmt.QueryString,

Params: stmt.Params,

Stmt: tx.Stmtx(stmt.Stmt),

}

}

// PrepareNamed returns an sqlx.NamedStmt

func (tx *Tx) PrepareNamed(query string) (*NamedStmt, error) {

return prepareNamed(tx, query)

}

// Stmt is an sqlx wrapper around sql.Stmt with extra functionality

type Stmt struct {

*sql.Stmt

unsafe bool

Mapper *reflectx.Mapper

}

// Unsafe returns a version of Stmt which will silently succeed to scan when

// columns in the SQL result have no fields in the destination struct.

func (s *Stmt) Unsafe() *Stmt {

return &Stmt{Stmt: s.Stmt, unsafe: true, Mapper: s.Mapper}

}

// Select using the prepared statement.

// Any placeholder parameters are replaced with supplied args.

func (s *Stmt) Select(dest interface{}, args ...interface{}) error {

return Select(&qStmt{s}, dest, "", args...)

}

// Get using the prepared statement.

// Any placeholder parameters are replaced with supplied args.

// An error is returned if the result set is empty.

func (s *Stmt) Get(dest interface{}, args ...interface{}) error {

return Get(&qStmt{s}, dest, "", args...)

}

// MustExec (panic) using this statement. Note that the query portion of the error

// output will be blank, as Stmt does not expose its query.

// Any placeholder parameters are replaced with supplied args.

func (s *Stmt) MustExec(args ...interface{}) sql.Result {

return MustExec(&qStmt{s}, "", args...)

}

// QueryRowx using this statement.

// Any placeholder parameters are replaced with supplied args.

func (s *Stmt) QueryRowx(args ...interface{}) *Row {

qs := &qStmt{s}

return qs.QueryRowx("", args...)

}

// Queryx using this statement.

// Any placeholder parameters are replaced with supplied args.

func (s *Stmt) Queryx(args ...interface{}) (*Rows, error) {

qs := &qStmt{s}

return qs.Queryx("", args...)

}

// qStmt is an unexposed wrapper which lets you use a Stmt as a Queryer & Execer by

// implementing those interfaces and ignoring the `query` argument.

type qStmt struct{ *Stmt }

func (q *qStmt) Query(query string, args ...interface{}) (*sql.Rows, error) {

return q.Stmt.Query(args...)

}

func (q *qStmt) Queryx(query string, args ...interface{}) (*Rows, error) {

r, err := q.Stmt.Query(args...)

if err != nil {

return nil, err

}

return &Rows{Rows: r, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}, err

}

func (q *qStmt) QueryRowx(query string, args ...interface{}) *Row {

rows, err := q.Stmt.Query(args...)

return &Row{rows: rows, err: err, unsafe: q.Stmt.unsafe, Mapper: q.Stmt.Mapper}

}

func (q *qStmt) Exec(query string, args ...interface{}) (sql.Result, error) {

return q.Stmt.Exec(args...)

}

// Rows is a wrapper around sql.Rows which caches costly reflect operations

// during a looped StructScan

type Rows struct {

*sql.Rows

unsafe bool

Mapper *reflectx.Mapper

// these fields cache memory use for a rows during iteration w/ structScan

started bool

meta fieldsMeta

values []interface{}

}

// SliceScan using this Rows.

func (r *Rows) SliceScan() ([]interface{}, error) {

return SliceScan(r)

}

// MapScan using this Rows.

func (r *Rows) MapScan(dest map[string]interface{}) error {

return MapScan(r, dest)

}

// StructScan is like sql.Rows.Scan, but scans a single Row into a single Struct.

// Use this and iterate over Rows manually when the memory load of Select() might be

// prohibitive. *Rows.StructScan caches the reflect work of matching up column

// positions to fields to avoid that overhead per scan, which means it is not safe

// to run StructScan on the same Rows instance with different struct types.

func (r *Rows) StructScan(dest interface{}) error {

v := reflect.ValueOf(dest)

if v.Kind() != reflect.Ptr {

return errors.New("must pass a pointer, not a value, to StructScan destination")

}

v = v.Elem()

if !r.started {

columns, err := r.Columns()

if err != nil {

return err

}

m := r.Mapper

r.meta = traversalsByColumn(m, v.Type(), columns)

// if we are not unsafe and are missing fields, return an error

if f, err := missingFields(r.meta.fields); err != nil && !r.unsafe {

return fmt.Errorf("missing destination name %s in %T", columns[f], dest)

}

r.values = make([]interface{}, len(columns))

r.started = true

}

err := fieldsByTraversal(v, r.meta, r.values, true)

if err != nil {

return err

}

// scan into the struct field pointers and append to our results

err = r.Scan(r.values...)

if err != nil {

return err

}

return r.Err()

}

// Connect to a database and verify with a ping.

func Connect(driverName, dataSourceName string) (*DB, error) {

db, err := Open(driverName, dataSourceName)

if err != nil {

return nil, err

}

err = db.Ping()

if err != nil {

db.Close()

return nil, err

}

return db, nil

}

// MustConnect connects to a database and panics on error.

func MustConnect(driverName, dataSourceName string) *DB {

db, err := Connect(driverName, dataSourceName)

if err != nil {

panic(err)

}

return db

}

// Preparex prepares a statement.

func Preparex(p Preparer, query string) (*Stmt, error) {

s, err := p.Prepare(query)

if err != nil {

return nil, err

}

return &Stmt{Stmt: s, unsafe: isUnsafe(p), Mapper: mapperFor(p)}, err

}

// Select executes a query using the provided Queryer, and StructScans each row

// into dest, which must be a slice. If the slice elements are scannable, then

// the result set must have only one column. Otherwise, StructScan is used.

// The *sql.Rows are closed automatically.

// Any placeholder parameters are replaced with supplied args.

func Select(q Queryer, dest interface{}, query string, args ...interface{}) error {

rows, err := q.Queryx(query, args...)

if err != nil {

return err

}

// if something happens here, we want to make sure the rows are Closed

defer rows.Close()

return scanAll(rows, dest, false)

}

// Get does a QueryRow using the provided Queryer, and scans the resulting row

// to dest. If dest is scannable, the result must only have one column. Otherwise,

// StructScan is used. Get will return sql.ErrNoRows like row.Scan would.

// Any placeholder parameters are replaced with supplied args.

// An error is returned if the result set is empty.

func Get(q Queryer, dest interface{}, query string, args ...interface{}) error {

r := q.QueryRowx(query, args...)

return r.scanAny(dest, false)

}

// LoadFile exec's every statement in a file (as a single call to Exec).

// LoadFile may return a nil *sql.Result if errors are encountered locating or

// reading the file at path. LoadFile reads the entire file into memory, so it

// is not suitable for loading large data dumps, but can be useful for initializing

// schemas or loading indexes.

//

// FIXME: this does not really work with multi-statement files for mattn/go-sqlite3

// or the go-mysql-driver/mysql drivers; pq seems to be an exception here. Detecting

// this by requiring something with DriverName() and then attempting to split the

// queries will be difficult to get right, and its current driver-specific behavior

// is deemed at least not complex in its incorrectness.

func LoadFile(e Execer, path string) (*sql.Result, error) {

realpath, err := filepath.Abs(path)

if err != nil {

return nil, err

}

contents, err := ioutil.ReadFile(realpath)

if err != nil {

return nil, err

}

res, err := e.Exec(string(contents))

return &res, err

}

// MustExec execs the query using e and panics if there was an error.

// Any placeholder parameters are replaced with supplied args.

func MustExec(e Execer, query string, args ...interface{}) sql.Result {

res, err := e.Exec(query, args...)

if err != nil {

panic(err)

}

return res

}

// SliceScan using this Rows.

func (r *Row) SliceScan() ([]interface{}, error) {

return SliceScan(r)

}

// MapScan using this Rows.

func (r *Row) MapScan(dest map[string]interface{}) error {

return MapScan(r, dest)

}

func (r *Row) scanAny(dest interface{}, structOnly bool) error {

if r.err != nil {

return r.err

}

if r.rows == nil {

r.err = sql.ErrNoRows

return r.err

}

defer r.rows.Close()

v := reflect.ValueOf(dest)

if v.Kind() != reflect.Ptr {

return errors.New("must pass a pointer, not a value, to StructScan destination")

}

if v.IsNil() {

return errors.New("nil pointer passed to StructScan destination")

}

base := reflectx.Deref(v.Type())

scannable := isScannable(base)

if structOnly && scannable {

return structOnlyError(base)

}

columns, err := r.Columns()

if err != nil {

return err

}

if scannable && len(columns) > 1 {

return fmt.Errorf("scannable dest type %s with >1 columns (%d) in result", base.Kind(), len(columns))

}

if scannable {

return r.Scan(dest)

}

m := r.Mapper

meta := traversalsByColumn(m, v.Type(), columns)

// if we are not unsafe and are missing fields, return an error

if f, err := missingFields(meta.fields); err != nil && !r.unsafe {

return fmt.Errorf("missing destination name %s in %T", columns[f], dest)

}

values := make([]interface{}, len(columns))

err = fieldsByTraversal(v, meta, values, true)

if err != nil {

return err

}

// scan into the struct field pointers and append to our results

return r.Scan(values...)

}

// StructScan a single Row into dest.

func (r *Row) StructScan(dest interface{}) error {

return r.scanAny(dest, true)

}

// SliceScan a row, returning a []interface{} with values similar to MapScan.

// This function is primarily intended for use where the number of columns

// is not known. Because you can pass an []interface{} directly to Scan,

// it's recommended that you do that as it will not have to allocate new

// slices per row.

func SliceScan(r ColScanner) ([]interface{}, error) {

// ignore r.started, since we needn't use reflect for anything.

columns, err := r.Columns()

if err != nil {

return []interface{}{}, err

}

values := make([]interface{}, len(columns))

for i := range values {

values[i] = new(interface{})

}

err = r.Scan(values...)

if err != nil {

return values, err

}

for i := range columns {

values[i] = *(values[i].(*interface{}))

}

return values, r.Err()

}

// MapScan scans a single Row into the dest map[string]interface{}.

// Use this to get results for SQL that might not be under your control

// (for instance, if you're building an interface for an SQL server that

// executes SQL from input). Please do not use this as a primary interface!

// This will modify the map sent to it in place, so reuse the same map with

// care. Columns which occur more than once in the result will overwrite

// each other!

func MapScan(r ColScanner, dest map[string]interface{}) error {

// ignore r.started, since we needn't use reflect for anything.

columns, err := r.Columns()

if err != nil {

return err

}

values := make([]interface{}, len(columns))

for i := range values {

values[i] = new(interface{})

}

err = r.Scan(values...)

if err != nil {

return err

}

for i, column := range columns {

dest[column] = *(values[i].(*interface{}))

}

return r.Err()

}

type rowsi interface {

Close() error

Columns() ([]string, error)

Err() error

Next() bool

Scan(...interface{}) error

}

// structOnlyError returns an error appropriate for type when a non-scannable

// struct is expected but something else is given

func structOnlyError(t reflect.Type) error {

isStruct := t.Kind() == reflect.Struct

isScanner := reflect.PtrTo(t).Implements(_scannerInterface)

if !isStruct {

return fmt.Errorf("expected %s but got %s", reflect.Struct, t.Kind())

}

if isScanner {

return fmt.Errorf("structscan expects a struct dest but the provided struct type %s implements scanner", t.Name())

}

return fmt.Errorf("expected a struct, but struct %s has no exported fields", t.Name())

}

// scanAll scans all rows into a destination, which must be a slice of any

// type. If the destination slice type is a Struct, then StructScan will be

// used on each row. If the destination is some other kind of base type, then

// each row must only have one column which can scan into that type. This

// allows you to do something like:

//

// rows, _ := db.Query("select id from people;")

// var ids []int

// scanAll(rows, &ids, false)

//

// and ids will be a list of the id results. I realize that this is a desirable

// interface to expose to users, but for now it will only be exposed via changes

// to `Get` and `Select`. The reason that this has been implemented like this is

// this is the only way to not duplicate reflect work in the new API while

// maintaining backwards compatibility.

func scanAll(rows rowsi, dest interface{}, structOnly bool) error {

var v, vp reflect.Value

value := reflect.ValueOf(dest)

// json.Unmarshal returns errors for these

if value.Kind() != reflect.Ptr {

return errors.New("must pass a pointer, not a value, to StructScan destination")

}

if value.IsNil() {

return errors.New("nil pointer passed to StructScan destination")

}

direct := reflect.Indirect(value)

slice, err := baseType(value.Type(), reflect.Slice)

if err != nil {

return err

}

isPtr := slice.Elem().Kind() == reflect.Ptr

base := reflectx.Deref(slice.Elem())

scannable := isScannable(base)

if structOnly && scannable {

return structOnlyError(base)

}

columns, err := rows.Columns()

if err != nil {

return err

}

// if it's a base type make sure it only has 1 column; if not return an error

if scannable && len(columns) > 1 {

return fmt.Errorf("non-struct dest type %s with >1 columns (%d)", base.Kind(), len(columns))

}

if !scannable {

var values []interface{}

var m *reflectx.Mapper

switch rows.(type) {

case *Rows:

m = rows.(*Rows).Mapper

default:

m = mapper()

}

meta := traversalsByColumn(m, base, columns)

// if we are not unsafe and are missing fields, return an error

if f, err := missingFields(meta.fields); err != nil && !isUnsafe(rows) {

return fmt.Errorf("missing destination name %s in %T", columns[f], dest)

}

values = make([]interface{}, len(columns))

for rows.Next() {

// create a new struct type (which returns PtrTo) and indirect it

vp = reflect.New(base)

v = reflect.Indirect(vp)

err = fieldsByTraversal(v, meta, values, true)

if err != nil {

return err

}

// scan into the struct field pointers and append to our results

err = rows.Scan(values...)

if err != nil {

return err

}

if isPtr {

direct.Set(reflect.Append(direct, vp))

} else {

direct.Set(reflect.Append(direct, v))

}

}

} else {

for rows.Next() {

vp = reflect.New(base)

err = rows.Scan(vp.Interface())

if err != nil {

return err

}

// append

if isPtr {

direct.Set(reflect.Append(direct, vp))

} else {

direct.Set(reflect.Append(direct, reflect.Indirect(vp)))

}

}

}

return rows.Err()

}

// FIXME: StructScan was the very first bit of API in sqlx, and now unfortunately

// it doesn't really feel like it's named properly. There is an incongruency

// between this and the way that StructScan (which might better be ScanStruct

// anyway) works on a rows object.

// StructScan all rows from an sql.Rows or an sqlx.Rows into the dest slice.

// StructScan will scan in the entire rows result, so if you do not want to

// allocate structs for the entire result, use Queryx and see sqlx.Rows.StructScan.

// If rows is sqlx.Rows, it will use its mapper, otherwise it will use the default.

func StructScan(rows rowsi, dest interface{}) error {