v0.0.44

sq/structscanner.go

@@ -0,0 +1,201 @@
+package sq
+
+import (
+	"errors"
+	"fmt"
+	"github.com/jmoiron/sqlx"
+	"github.com/jmoiron/sqlx/reflectx"
+	"reflect"
+)
+
+// forked from sqlx, but added ability to unmarshal optional-nested structs
+
+type StructScanner struct {
+	rows   *sqlx.Rows
+	Mapper *reflectx.Mapper
+	unsafe bool
+
+	fields  [][]int
+	values  []any
+	columns []string
+}
+
+func NewStructScanner(rows *sqlx.Rows, unsafe bool) *StructScanner {
+	return &StructScanner{
+		rows:   rows,
+		Mapper: reflectx.NewMapper("db"),
+		unsafe: unsafe,
+	}
+}
+
+func (r *StructScanner) Start(dest any) error {
+	v := reflect.ValueOf(dest)
+
+	if v.Kind() != reflect.Ptr {
+		return errors.New("must pass a pointer, not a value, to StructScan destination")
+	}
+
+	columns, err := r.rows.Columns()
+	if err != nil {
+		return err
+	}
+
+	r.columns = columns
+	r.fields = r.Mapper.TraversalsByName(v.Type(), columns)
+	// if we are not unsafe and are missing fields, return an error
+	if f, err := missingFields(r.fields); err != nil && !r.unsafe {
+		return fmt.Errorf("missing destination name %s in %T", columns[f], dest)
+	}
+	r.values = make([]interface{}, len(columns))
+
+	return nil
+}
+
+// StructScan forked from github.com/jmoiron/sqlx@v1.3.5/sqlx.go
+// does also wok with nullabel structs (from LEFT JOIN's)
+func (r *StructScanner) StructScanExt(dest any) error {
+	v := reflect.ValueOf(dest)
+
+	if v.Kind() != reflect.Ptr {
+		return errors.New("must pass a pointer, not a value, to StructScan destination")
+	}
+
+	// ========= STEP 1 ::  =========
+
+	v = v.Elem()
+
+	err := fieldsByTraversal(v, r.fields, r.values)
+	if err != nil {
+		return err
+	}
+	// scan into the struct field pointers and append to our results
+	err = r.rows.Scan(r.values...)
+	if err != nil {
+		return err
+	}
+
+	nullStructs := make(map[string]bool)
+
+	for i, traversal := range r.fields {
+		if len(traversal) == 0 {
+			continue
+		}
+
+		isnsil := reflect.ValueOf(r.values[i]).Elem().IsNil()
+
+		for i := 1; i < len(traversal); i++ {
+
+			canParentNil := reflectx.FieldByIndexes(v, traversal[0:i]).Kind() == reflect.Pointer
+
+			k := fmt.Sprintf("%v", traversal[0:i])
+			if v, ok := nullStructs[k]; ok {
+
+				nullStructs[k] = canParentNil && v && isnsil
+
+			} else {
+				nullStructs[k] = canParentNil && isnsil
+			}
+		}
+
+	}
+
+	forcenulled := make(map[string]bool)
+
+	for i, traversal := range r.fields {
+		if len(traversal) == 0 {
+			continue
+		}
+
+		anyparentnull := false
+		for i := 1; i < len(traversal); i++ {
+			k := fmt.Sprintf("%v", traversal[0:i])
+			if nv, ok := nullStructs[k]; ok && nv {
+
+				if _, ok := forcenulled[k]; !ok {
+					f := reflectx.FieldByIndexes(v, traversal[0:i])
+					f.Set(reflect.New(f.Type().Elem())) // set to nil
+					forcenulled[k] = true
+				}
+
+				anyparentnull = true
+				break
+
+			}
+		}
+
+		if anyparentnull {
+			continue
+		}
+
+		f := reflectx.FieldByIndexes(v, traversal)
+
+		val1 := reflect.ValueOf(r.values[i])
+		val2 := val1.Elem()
+		val3 := val2.Elem()
+
+		if val2.IsNil() {
+			if f.Kind() != reflect.Pointer {
+				return errors.New(fmt.Sprintf("Cannot set field %v to NULL value from column '%s' (type: %s)", traversal, r.columns[i], f.Type().String()))
+			}
+
+			f.Set(reflect.New(f.Type().Elem())) // set to nil
+		} else {
+			f.Set(val3)
+		}
+
+	}
+
+	return r.rows.Err()
+}
+
+// StructScan forked from github.com/jmoiron/sqlx@v1.3.5/sqlx.go
+// without (relevant) changes
+func (r *StructScanner) StructScanBase(dest any) 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()
+
+	err := fieldsByTraversal(v, r.fields, r.values)
+	if err != nil {
+		return err
+	}
+	// scan into the struct field pointers and append to our results
+	err = r.rows.Scan(r.values...)
+	if err != nil {
+		return err
+	}
+	return r.rows.Err()
+}
+
+// fieldsByTraversal forked from github.com/jmoiron/sqlx@v1.3.5/sqlx.go
+func fieldsByTraversal(v reflect.Value, traversals [][]int, values []interface{}) error {
+	v = reflect.Indirect(v)
+	if v.Kind() != reflect.Struct {
+		return errors.New("argument not a struct")
+	}
+
+	for i, traversal := range traversals {
+		if len(traversal) == 0 {
+			values[i] = new(interface{})
+			continue
+		}
+		f := reflectx.FieldByIndexes(v, traversal)
+
+		values[i] = reflect.New(reflect.PointerTo(f.Type())).Interface()
+	}
+	return nil
+}
+
+// missingFields forked from github.com/jmoiron/sqlx@v1.3.5/sqlx.go
+func missingFields(transversals [][]int) (field int, err error) {
+	for i, t := range transversals {
+		if len(t) == 0 {
+			return i, errors.New("missing field")
+		}
+	}
+	return 0, nil
+}