0d6f01d340
There is a gotcha in golang (go figure!) resulting from the difference between a nil slice and an empty slice. While the length of both are 0, the JSON encoder will interpret the nil slice as 'null' and the empty slice as '[]'. Other libraries (i.e. ActiveRecord) will return an empty array when no values are found. I have found that this translates into better client-side code, since you don't have to protect against null arrays. See 'http://danott.co/posts/json-marshalling-empty-slices-to-empty-arrays-in-go.html' for more information.
102 lines
2.2 KiB
Go
102 lines
2.2 KiB
Go
package gorm
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import (
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"fmt"
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"reflect"
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)
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func Query(scope *Scope) {
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defer scope.Trace(NowFunc())
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var (
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isSlice bool
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isPtr bool
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anyRecordFound bool
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destType reflect.Type
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)
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var dest = scope.IndirectValue()
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if value, ok := scope.InstanceGet("gorm:query_destination"); ok {
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dest = reflect.Indirect(reflect.ValueOf(value))
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}
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if orderBy, ok := scope.InstanceGet("gorm:order_by_primary_key"); ok {
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if primaryKey := scope.PrimaryKey(); primaryKey != "" {
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scope.Search = scope.Search.clone().order(fmt.Sprintf("%v.%v %v", scope.QuotedTableName(), primaryKey, orderBy))
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}
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}
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if dest.Kind() == reflect.Slice {
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isSlice = true
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destType = dest.Type().Elem()
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if destType.Kind() == reflect.Ptr {
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isPtr = true
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destType = destType.Elem()
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}
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} else {
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scope.Search = scope.Search.clone().limit(1)
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}
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scope.prepareQuerySql()
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if !scope.HasError() {
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rows, err := scope.DB().Query(scope.Sql, scope.SqlVars...)
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if scope.Err(err) != nil {
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return
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}
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defer rows.Close()
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for rows.Next() {
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anyRecordFound = true
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elem := dest
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if isSlice {
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elem = reflect.New(destType).Elem()
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}
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columns, _ := rows.Columns()
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var values []interface{}
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fields := scope.New(elem.Addr().Interface()).Fields()
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for _, value := range columns {
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if field, ok := fields[value]; ok {
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values = append(values, field.Field.Addr().Interface())
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} else {
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var ignore interface{}
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values = append(values, &ignore)
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}
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}
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scope.Err(rows.Scan(values...))
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if isSlice {
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if isPtr {
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dest.Set(reflect.Append(dest, elem.Addr()))
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} else {
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dest.Set(reflect.Append(dest, elem))
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}
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}
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}
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if !anyRecordFound {
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if isSlice && dest.IsNil() {
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var emptySliceType reflect.Type
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if isPtr {
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emptySliceType = reflect.SliceOf(reflect.PtrTo(destType))
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} else {
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emptySliceType = reflect.SliceOf(destType)
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}
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dest.Set(reflect.MakeSlice(emptySliceType, 0, 0))
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}
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scope.Err(RecordNotFound)
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}
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}
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}
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func AfterQuery(scope *Scope) {
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scope.CallMethod("AfterFind")
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}
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func init() {
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DefaultCallback.Query().Register("gorm:query", Query)
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DefaultCallback.Query().Register("gorm:after_query", AfterQuery)
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}
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