Golang Model.Fields方法代码示例

func fieldHasDefault(m driver.Model, f *Field) bool {
	if f.Default != "" {
		return true
	}
	fields := m.Fields()
	idx := fields.MNameMap[f.Name]
	return fields.HasDefault(idx)
}

func (s sortModels) less(mi, mj driver.Model) bool {
	for _, v := range mi.Fields().References {
		if v.Model == mj {
			return false
		}
		if v.Model != mi && !s.less(v.Model, mj) {
			return false
		}
	}
	return true
}

func (b *Backend) Insert(db *sql.DB, m driver.Model, query string, args ...interface{}) (driver.Result, error) {
	fields := m.Fields()
	if fields.AutoincrementPk {
		q := query + " RETURNING " + fields.MNames[fields.PrimaryKey]
		var id int64
		err := db.QueryRow(q, args...).Scan(&id)
		// We need to perform a "real" insert to find the real error, so
		// just let the code fall to the Exec at the end of the function
		// if there's an error.
		if err == nil {
			return insertResult(id), nil
		}
	}
	return db.Exec(query, args...)
}

func (b *SqlBackend) AddFields(db *DB, m driver.Model, prevTable *Table, newTable *Table, fields []*Field) error {
	modelFields := m.Fields()
	tableName := db.QuoteIdentifier(m.Table())
	for _, v := range fields {
		idx := modelFields.MNameMap[v.Name]
		field := v
		hasDefault := modelFields.HasDefault(idx)
		if hasDefault && v.HasConstraint(ConstraintNotNull) {
			// ORM level default
			// Must be added as nullable first, then the default value
			// must be set and finally the field has to be altered to be
			// nullable.
			field = field.Copy()
			var constraints []*Constraint
			for _, v := range field.Constraints {
				if v.Type != ConstraintNotNull {
					constraints = append(constraints, v)
				}
			}
			field.Constraints = constraints
		}
		sql, cons, err := field.SQL(db, m, newTable)
		if err != nil {
			return err
		}
		if _, err = db.Exec(fmt.Sprintf("ALTER TABLE %s ADD COLUMN %s", tableName, sql)); err != nil {
			return err
		}
		if hasDefault {
			value := modelFields.DefaultValue(idx)
			fieldName := db.QuoteIdentifier(v.Name)
			if _, err := db.Exec(fmt.Sprintf("UPDATE %s SET %s = ?", tableName, fieldName), value); err != nil {
				return err
			}
			if v.HasConstraint(ConstraintNotNull) {
				if err := db.Backend().AlterField(db, m, newTable, field, v); err != nil {
					return err
				}
			}
		}
		for _, c := range cons {
			if _, err = db.Exec(fmt.Sprintf("ALTER TABLE %s ADD CONSTRAINT %s", tableName, c)); err != nil {
				return err
			}
		}
	}
	return nil
}

func (d *Driver) mergeTable(m driver.Model, prevTable *Table, newTable *Table) error {
	existing := make(map[string]*Field)
	for _, v := range prevTable.Fields {
		existing[v.Name] = v
	}
	var missing []*Field
	for _, v := range newTable.Fields {
		prev := existing[v.Name]
		if prev == nil {
			// Check if we can add the field
			if v.HasConstraint(ConstraintNotNull) && !fieldHasDefault(m, v) {
				return fmt.Errorf("can't add NOT NULL field %q to table %q without a default value", v.Name, m.Table())
			}
			if v.HasConstraint(ConstraintPrimaryKey) {
				return fmt.Errorf("can't add PRIMARY KEY field %q to table %q", v.Name, m.Table())
			}
			missing = append(missing, v)
		} else {
			if prev.Type != v.Type {
				// Check the Kind
				k1, len1 := TypeKind(prev.Type)
				k2, len2 := TypeKind(v.Type)
				if k1 == k2 {
					// Check lengths
					if len1 != len2 {
					}
					continue
				}
				// Check if we can transform the kind
				fields := m.Fields()
				idx := fields.MNameMap[v.Name]
				modelName := fields.QNames[idx]
				modelType := fields.Types[idx]
				return fmt.Errorf("field %q on table %q is of type %s which is not compatible with the model field %q of type %s (%s)",
					v.Name, m.Table(), prev.Type, modelName, v.Type, modelType)
			}
		}
	}
	if len(missing) > 0 {
		if err := d.backend.AddFields(d.db, m, prevTable, newTable, missing); err != nil {
			return err
		}
	}
	return nil
}

func (d *Driver) outValues(m driver.Model, out interface{}) (reflect.Value, *driver.Fields, []interface{}, []*scanner, error) {
	val := reflect.ValueOf(out)
	if !val.IsValid() {
		// Untyped nil pointer
		return reflect.Value{}, nil, nil, nil, nil
	}
	vt := val.Type()
	if vt.Kind() != reflect.Ptr {
		return reflect.Value{}, nil, nil, nil, fmt.Errorf("can't set object of type %T. Please, pass a %v rather than a %v", out, reflect.PtrTo(vt), vt)
	}
	if vt.Elem().Kind() == reflect.Ptr && vt.Elem().Elem().Kind() == reflect.Struct {
		// Received a pointer to pointer. Always create a new object,
		// to avoid overwriting the previous result.
		val = val.Elem()
		el := reflect.New(val.Type().Elem())
		val.Set(el)
	}
	for val.Kind() == reflect.Ptr {
		el := val.Elem()
		if !el.IsValid() {
			if !val.CanSet() {
				// Typed nil pointer
				return reflect.Value{}, nil, nil, nil, nil
			}
			el = reflect.New(val.Type().Elem())
			val.Set(el)
		}
		val = el
	}
	fields := m.Fields()
	if fields == nil {
		// Skipped model
		return reflect.Value{}, nil, nil, nil, nil
	}
	values := make([]interface{}, len(fields.Indexes))
	scanners := make([]*scanner, len(fields.Indexes))
	for ii, v := range fields.Indexes {
		field := d.fieldByIndex(val, v, true)
		tag := fields.Tags[ii]
		s := newScanner(&field, tag, d.backend)
		scanners[ii] = s
		values[ii] = s
	}
	return val, fields, values, scanners, nil
}

func (d *Driver) createIndex(m driver.Model, idx *index.Index, name string) error {
	has, err := d.backend.HasIndex(d.db, m, idx, name)
	if err != nil {
		return err
	}
	if has {
		return nil
	}

	buf := getBuffer()
	buf.WriteString("CREATE ")
	if idx.Unique {
		buf.WriteString("UNIQUE ")
	}
	buf.WriteString("INDEX ")
	buf.WriteString(name)
	buf.WriteString(" ON \"")
	buf.WriteString(m.Table())
	buf.WriteString("\" (")
	fields := m.Fields()
	for _, v := range idx.Fields {
		name, _, err := fields.Map(v)
		if err != nil {
			return err
		}
		buf.WriteByte('"')
		buf.WriteString(name)
		buf.WriteByte('"')
		if DescField(idx, v) {
			buf.WriteString(" DESC")
		}
		buf.WriteByte(',')
	}
	buf.Truncate(buf.Len() - 1)
	buf.WriteString(")")
	_, err = d.db.Exec(buftos(buf))
	putBuffer(buf)
	return err
}

func (d *Driver) Insert(m driver.Model, data interface{}) (driver.Result, error) {
	var id int64
	fields := m.Fields()
	var pkVal *reflect.Value
	// TODO: If the PK is supplied by the user rather than auto-assigned, it
	// might conflict with PKs generated by datastore.AllocateIDs().
	if fields.PrimaryKey >= 0 {
		p := d.primaryKey(fields, data)
		if p.IsValid() && types.Kind(p.Kind()) == types.Int {
			id = p.Int()
			if id == 0 {
				// Must assign PK field value after calling AllocateIDs
				pkVal = &p
			}
		}
	}
	name := m.Table()
	// Make all objects of a given kind ancestors of the same key. While
	// this hurts scalability, it makes all reads strongly consistent.
	parent := d.parentKey(m)
	var err error
	if id == 0 {
		id, _, err = datastore.AllocateIDs(d.c, name, parent, 1)
		if err != nil {
			return nil, err
		}
	}
	if fields.AutoincrementPk && pkVal != nil {
		pkVal.SetInt(int64(id))
	}
	key := datastore.NewKey(d.c, name, "", id, parent)
	log.Debugf("DATASTORE: put %s %v", key, data)
	_, err = datastore.Put(d.c, key, data)
	if err != nil {
		return nil, err
	}
	return &result{key: key, count: 1}, nil
}

func (d *Driver) makeTable(m driver.Model) (*Table, error) {
	fields := m.Fields()
	names := fields.MNames
	qnames := fields.QNames
	ftypes := fields.Types
	tags := fields.Tags
	dbFields := make([]*Field, len(names))
	for ii, v := range names {
		typ := ftypes[ii]
		tag := tags[ii]
		ft, err := d.backend.FieldType(typ, tag)
		if err != nil {
			return nil, err
		}
		def := tag.Value("default")
		if fields.HasDefault(ii) {
			// Handled by the ORM
			def = ""
		}
		if def != "" {
			if driver.IsFunc(def) {
				fname, _ := driver.SplitFuncArgs(def)
				fn, err := d.backend.Func(fname, ftypes[ii])
				if err != nil {
					if err == ErrFuncNotSupported {
						err = fmt.Errorf("backend %s does not support function %s", d.backend.Name(), tag.Value("default"))
					}
					return nil, err
				}
				def = fn
			} else {
				def = driver.UnescapeDefault(def)
				if typ.Kind() == reflect.String {
					def = d.db.QuoteString(def)
				}
			}
		}
		field := &Field{
			Name:    v,
			Type:    ft,
			Default: def,
		}
		if tag.Has("notnull") {
			field.AddConstraint(ConstraintNotNull)
		}
		if d.isPrimaryKey(fields, ii, tag) {
			field.AddConstraint(ConstraintPrimaryKey)
		} else if tag.Has("unique") {
			field.AddConstraint(ConstraintUnique)
		}
		if tag.Has("auto_increment") {
			field.AddOption(OptionAutoIncrement)
		}
		if ref := fields.References[qnames[ii]]; ref != nil {
			fk, _, err := ref.Model.Fields().Map(ref.Field)
			if err != nil {
				return nil, err
			}
			field.Constraints = append(field.Constraints, &Constraint{
				Type:       ConstraintForeignKey,
				References: MakeReference(ref.Model.Table(), fk),
			})
		}
		dbFields[ii] = field
	}
	return &Table{Fields: dbFields}, nil
}

func (d *Driver) saveParameters(m driver.Model, data interface{}) (reflect.Value, []string, []interface{}, error) {
	// data is guaranteed to be of m.Type()
	val := driver.Direct(reflect.ValueOf(data))
	fields := m.Fields()
	max := len(fields.MNames)
	names := make([]string, 0, max)
	values := make([]interface{}, 0, max)
	var err error
	if d.transforms != nil {
		for ii, v := range fields.Indexes {
			f := d.fieldByIndex(val, v, false)
			if !f.IsValid() {
				continue
			}
			if fields.OmitEmpty[ii] && driver.IsZero(f) {
				continue
			}
			ft := f.Type()
			var fval interface{}
			if _, ok := d.transforms[ft]; ok {
				fval, err = d.backend.TransformOutValue(f)
				if err != nil {
					return val, nil, nil, err
				}
				if fields.NullEmpty[ii] && driver.IsZero(reflect.ValueOf(fval)) {
					fval = nil
				}
			} else if !fields.NullEmpty[ii] || !driver.IsZero(f) {
				if c := codec.FromTag(fields.Tags[ii]); c != nil {
					fval, err = c.Encode(f.Interface())
					if err != nil {
						return val, nil, nil, err
					}
					if p := pipe.FromTag(fields.Tags[ii]); p != nil {
						data, err := p.Encode(fval.([]byte))
						if err != nil {
							return val, nil, nil, err
						}
						fval = data
					}
				} else {
					// Most sql drivers won't accept aliases for string type
					if ft.Kind() == reflect.String && ft != stringType {
						f = f.Convert(stringType)
					}
					fval = f.Interface()
				}
			}
			names = append(names, fields.MNames[ii])
			values = append(values, fval)
		}
	} else {
		for ii, v := range fields.Indexes {
			f := d.fieldByIndex(val, v, false)
			if !f.IsValid() {
				continue
			}
			if fields.OmitEmpty[ii] && driver.IsZero(f) {
				continue
			}
			var fval interface{}
			if !fields.NullEmpty[ii] || !driver.IsZero(f) {
				if c := codec.FromTag(fields.Tags[ii]); c != nil {
					fval, err = c.Encode(&f)
					if err != nil {
						return val, nil, nil, err
					}
				} else {
					ft := f.Type()
					// Most sql drivers won't accept aliases for string type
					if ft.Kind() == reflect.String && ft != stringType {
						f = f.Convert(stringType)
					}
					fval = f.Interface()
				}
			}
			names = append(names, fields.MNames[ii])
			values = append(values, fval)
		}
	}
	return val, names, values, nil
}

func (d *Driver) applyQuery(m driver.Model, dq *datastore.Query, q query.Q) (*datastore.Query, error) {
	var field *query.Field
	var op string
	switch x := q.(type) {
	case *query.Eq:
		field = &x.Field
		op = " ="
	case *query.Lt:
		field = &x.Field
		op = " <"
	case *query.Lte:
		field = &x.Field
		op = " <="
	case *query.Gt:
		field = &x.Field
		op = " >"
	case *query.Gte:
		field = &x.Field
		op = " >="
	case *query.And:
		var err error
		for _, v := range x.Conditions {
			dq, err = d.applyQuery(m, dq, v)
			if err != nil {
				return nil, err
			}
		}
	case nil:
	default:
		return nil, fmt.Errorf("datastore does not support %T queries", q)
	}
	if field != nil {
		if _, ok := field.Value.(query.F); ok {
			return nil, fmt.Errorf("datastore queries can't reference other properties (%v)", field.Value)
		}
		name := field.Field
		fields := m.Fields()
		idx, ok := fields.QNameMap[name]
		if !ok {
			return nil, fmt.Errorf("can't map field %q to a datastore name", name)
		}
		if strings.IndexByte(name, '.') >= 0 {
			// GAE flattens embedded fields, so we must remove
			// the parts of the field which refer to a flattened
			// field.
			indexes := fields.Indexes[idx]
			parts := strings.Split(name, ".")
			if len(indexes) == len(parts) {
				var final []string
				typ := fields.Type
				for ii, v := range indexes {
					f := typ.Field(v)
					if !f.Anonymous {
						final = append(final, parts[ii])
					}
					typ = f.Type
				}
				name = strings.Join(final, ".")
			}
		}
		log.Debugf("DATASTORE: filter %s %s %v", m, name+op, field.Value)
		dq = dq.Filter(name+op, field.Value)
	}
	return dq, nil
}