index: add composite id (#5269)

* index: add composite id

* index: add test cases of composite id

* index: improve the comments for the test cases of composite id

schema/index.go

@@ -1,6 +1,7 @@
 package schema
 
 import (
+	"fmt"
 	"sort"
 	"strconv"
 	"strings"
@@ -31,7 +32,12 @@ func (schema *Schema) ParseIndexes() map[string]Index {
 
 	for _, field := range schema.Fields {
 		if field.TagSettings["INDEX"] != "" || field.TagSettings["UNIQUEINDEX"] != "" {
-			for _, index := range parseFieldIndexes(field) {
+			fieldIndexes, err := parseFieldIndexes(field)
+			if err != nil {
+				schema.err = err
+				break
+			}
+			for _, index := range fieldIndexes {
 				idx := indexes[index.Name]
 				idx.Name = index.Name
 				if idx.Class == "" {
@@ -82,7 +88,7 @@ func (schema *Schema) LookIndex(name string) *Index {
 	return nil
 }
 
-func parseFieldIndexes(field *Field) (indexes []Index) {
+func parseFieldIndexes(field *Field) (indexes []Index, err error) {
 	for _, value := range strings.Split(field.Tag.Get("gorm"), ";") {
 		if value != "" {
 			v := strings.Split(value, ":")
@@ -106,7 +112,20 @@ func parseFieldIndexes(field *Field) (indexes []Index) {
 				}
 
 				if name == "" {
-					name = field.Schema.namer.IndexName(field.Schema.Table, field.Name)
+					subName := field.Name
+					const key = "COMPOSITE"
+					if composite, found := settings[key]; found {
+						if len(composite) == 0 || composite == key {
+							err = fmt.Errorf(
+								"The composite tag of %s.%s cannot be empty",
+								field.Schema.Name,
+								field.Name)
+							return
+						}
+						subName = composite
+					}
+					name = field.Schema.namer.IndexName(
+						field.Schema.Table, subName)
 				}
 
 				if (k == "UNIQUEINDEX") || settings["UNIQUE"] != "" {
@@ -138,5 +157,6 @@ func parseFieldIndexes(field *Field) (indexes []Index) {
 		}
 	}
 
+	err = nil
 	return
 }

schema/index_test.go

@@ -19,6 +19,36 @@ type UserIndex struct {
 	OID          int64  `gorm:"index:idx_id;index:idx_oid,unique"`
 	MemberNumber string `gorm:"index:idx_id,priority:1"`
 	Name7        string `gorm:"index:type"`
+
+	// Composite Index: Flattened structure.
+	Data0A string `gorm:"index:,composite:comp_id0"`
+	Data0B string `gorm:"index:,composite:comp_id0"`
+
+	// Composite Index: Nested structure.
+	Data1A string `gorm:"index:,composite:comp_id1"`
+	CompIdxLevel1C
+
+	// Composite Index: Unique and priority.
+	Data2A string `gorm:"index:,unique,composite:comp_id2,priority:2"`
+	CompIdxLevel2C
+}
+
+type CompIdxLevel1C struct {
+	CompIdxLevel1B
+	Data1C string `gorm:"index:,composite:comp_id1"`
+}
+
+type CompIdxLevel1B struct {
+	Data1B string `gorm:"index:,composite:comp_id1"`
+}
+
+type CompIdxLevel2C struct {
+	CompIdxLevel2B
+	Data2C string `gorm:"index:,unique,composite:comp_id2,priority:1"`
+}
+
+type CompIdxLevel2B struct {
+	Data2B string `gorm:"index:,unique,composite:comp_id2,priority:3"`
 }
 
 func TestParseIndex(t *testing.T) {
@@ -84,6 +114,36 @@ func TestParseIndex(t *testing.T) {
 			Type:   "",
 			Fields: []schema.IndexOption{{Field: &schema.Field{Name: "Name7"}}},
 		},
+		"idx_user_indices_comp_id0": {
+			Name: "idx_user_indices_comp_id0",
+			Type: "",
+			Fields: []schema.IndexOption{{
+				Field: &schema.Field{Name: "Data0A"},
+			}, {
+				Field: &schema.Field{Name: "Data0B"},
+			}},
+		},
+		"idx_user_indices_comp_id1": {
+			Name: "idx_user_indices_comp_id1",
+			Fields: []schema.IndexOption{{
+				Field: &schema.Field{Name: "Data1A"},
+			}, {
+				Field: &schema.Field{Name: "Data1B"},
+			}, {
+				Field: &schema.Field{Name: "Data1C"},
+			}},
+		},
+		"idx_user_indices_comp_id2": {
+			Name:  "idx_user_indices_comp_id2",
+			Class: "UNIQUE",
+			Fields: []schema.IndexOption{{
+				Field: &schema.Field{Name: "Data2C"},
+			}, {
+				Field: &schema.Field{Name: "Data2A"},
+			}, {
+				Field: &schema.Field{Name: "Data2B"},
+			}},
+		},
 	}
 
 	indices := user.ParseIndexes()