Select statement execution and mapping to struct or slice added.

sqlbuilder/execution/execution.go

@@ -0,0 +1,144 @@
+package execution
+
+import (
+	"database/sql"
+	"errors"
+	"github.com/serenize/snaker"
+	"reflect"
+)
+
+func Execute(db *sql.DB, query string, destinationPtr interface{}) error {
+	if db == nil {
+		return errors.New("db is nil")
+	}
+
+	if destinationPtr == nil {
+		return errors.New("Destination is nil ")
+	}
+
+	destinationType := reflect.TypeOf(destinationPtr)
+	if destinationType.Kind() != reflect.Ptr {
+		return errors.New("Destination has to be a pointer to slice or pointer to struct ")
+	}
+
+	rows, err := db.Query(query)
+
+	if err != nil {
+		return err
+	}
+
+	columnNames, _ := rows.Columns()
+	columnTypes, _ := rows.ColumnTypes()
+	values := createScanValue(columnTypes)
+
+	for rows.Next() {
+		err := rows.Scan(values...)
+
+		if err != nil {
+			return err
+		}
+
+		if destinationType.Elem().Kind() == reflect.Slice {
+
+			destinationStructPtr := newElemForSlice(destinationPtr)
+
+			err = mapValuesToStruct(columnNames, values, destinationStructPtr)
+
+			if err != nil {
+				return err
+			}
+
+			appendElemToSlice(destinationPtr, destinationStructPtr)
+		} else if destinationType.Elem().Kind() == reflect.Struct {
+			return mapValuesToStruct(columnNames, values, destinationPtr)
+		}
+	}
+
+	err = rows.Err()
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func appendElemToSlice(slice interface{}, obj interface{}) {
+	//spew.Dump(slice)
+	sliceValue := reflect.ValueOf(slice).Elem()
+
+	sliceValue.Set(reflect.Append(sliceValue, reflect.ValueOf(obj).Elem()))
+}
+
+func newElemForSlice(destinationSlicePtr interface{}) interface{} {
+	destinationSliceType := reflect.TypeOf(destinationSlicePtr).Elem()
+
+	return reflect.New(destinationSliceType.Elem()).Interface()
+}
+
+func mapValuesToStruct(columnNames []string, row []interface{}, destination interface{}) error {
+	structType := reflect.TypeOf(destination).Elem()
+	structValue := reflect.ValueOf(destination).Elem()
+
+	for i := 0; i < structType.NumField(); i++ {
+		fieldType := structType.Field(i)
+		fieldValue := structValue.Field(i)
+
+		fieldName := fieldType.Name
+
+		//columnName := structName + "." + fieldName
+		columnName := snaker.CamelToSnake(fieldName)
+
+		rowIndex := getIndex(columnNames, columnName)
+
+		if rowIndex < 0 {
+			continue
+		}
+
+		rowColumnValue := reflect.ValueOf(row[rowIndex])
+
+		setReflectValue(rowColumnValue, fieldValue)
+	}
+
+	return nil
+}
+
+func setReflectValue(source, destination reflect.Value) {
+	if destination.Kind() == reflect.Ptr {
+		if source.Kind() == reflect.Ptr {
+			destination.Set(source)
+		} else {
+			destination.Set(source.Addr())
+		}
+	} else {
+		if source.Kind() == reflect.Ptr {
+			destination.Set(source.Elem())
+		} else {
+			destination.Set(source)
+		}
+	}
+}
+
+func getIndex(list []string, text string) int {
+	for i, str := range list {
+		if str == text {
+			return i
+		}
+	}
+
+	return -1
+}
+
+func createScanValue(columnTypes []*sql.ColumnType) []interface{} {
+	values := make([]interface{}, len(columnTypes))
+
+	for i, sqlColumnType := range columnTypes {
+		columnType := sqlColumnType.ScanType()
+
+		columnValue := reflect.New(columnType)
+
+		values[i] = columnValue.Interface()
+	}
+
+	return values
+}

sqlbuilder/statement.go

@@ -2,7 +2,10 @@ package sqlbuilder
 
 import (
 	"bytes"
+	"database/sql"
 	"fmt"
+	"github.com/sub0Zero/go-sqlbuilder/sqlbuilder/execution"
+	"reflect"
 	"regexp"
 
 	"github.com/dropbox/godropbox/errors"
@@ -11,6 +14,7 @@ import (
 type Statement interface {
 	// String returns generated SQL as string.
 	String(database string) (sql string, err error)
+	Execute(db *sql.DB, destination interface{}) error
 }
 
 type SelectStatement interface {
@@ -133,6 +137,10 @@ type unionStatementImpl struct {
 	unique bool
 }
 
+func (us *unionStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (us *unionStatementImpl) Where(expression BoolExpression) UnionStatement {
 	us.where = expression
 	return us
@@ -305,6 +313,22 @@ type selectStatementImpl struct {
 	distinct       bool
 }
 
+func (s *selectStatementImpl) Execute(db *sql.DB, destination interface{}) error {
+	destinationType := reflect.TypeOf(destination)
+
+	if destinationType.Kind() == reflect.Ptr && destinationType.Elem().Kind() == reflect.Struct {
+		s.Limit(1)
+	}
+
+	query, err := s.String("dvds")
+
+	if err != nil {
+		return err
+	}
+
+	return execution.Execute(db, query, destination)
+}
+
 func (s *selectStatementImpl) Copy() SelectStatement {
 	ret := *s
 	return &ret
@@ -495,6 +519,10 @@ type insertStatementImpl struct {
 	ignore                bool
 }
 
+func (i *insertStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (s *insertStatementImpl) Add(
 	row ...Expression) InsertStatement {
 
@@ -665,6 +693,10 @@ type updateStatementImpl struct {
 	comment      string
 }
 
+func (u *updateStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (u *updateStatementImpl) Set(
 	column NonAliasColumn,
 	expression Expression) UpdateStatement {
@@ -808,6 +840,10 @@ type deleteStatementImpl struct {
 	comment string
 }
 
+func (d *deleteStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (d *deleteStatementImpl) Where(expression BoolExpression) DeleteStatement {
 	d.where = expression
 	return d
@@ -895,6 +931,10 @@ type tableLock struct {
 	w bool
 }
 
+func (l *lockStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 // AddReadLock takes read lock on the table.
 func (s *lockStatementImpl) AddReadLock(t *Table) LockStatement {
 	s.locks = append(s.locks, tableLock{t: t, w: false})
@@ -951,6 +991,10 @@ func NewUnlockStatement() UnlockStatement {
 type unlockStatementImpl struct {
 }
 
+func (u *unlockStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (s *unlockStatementImpl) String(database string) (sql string, err error) {
 	return "UNLOCK TABLES", nil
 }
@@ -968,6 +1012,10 @@ type gtidNextStatementImpl struct {
 	gno uint64
 }
 
+func (g *gtidNextStatementImpl) Execute(db *sql.DB, data interface{}) error {
+	return nil
+}
+
 func (s *gtidNextStatementImpl) String(database string) (sql string, err error) {
 	// This statement sets a session local variable defining what the next transaction ID is.  It
 	// does not interact with other MySQL sessions. It is neither a DDL nor DML statement, so we