Add support for excluding a field from an index in the model struct.

dialect_sqlite3.go

@@ -27,7 +27,7 @@ func (s *sqlite3) DataTypeOf(field *StructField) string {
 	if sqlType == "" {
 		switch dataValue.Kind() {
 		case reflect.Bool:
-			sqlType = "bool"
+			sqlType = "numeric"
 		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uintptr:
 			if field.IsPrimaryKey {
 				field.TagSettings["AUTO_INCREMENT"] = "AUTO_INCREMENT"

migration_test.go

@@ -5,6 +5,7 @@ import (
 	"database/sql/driver"
 	"errors"
 	"fmt"
+	"os"
 	"reflect"
 	"testing"
 	"time"
@@ -436,3 +437,50 @@ func TestMultipleIndexes(t *testing.T) {
 		t.Error("MultipleIndexes unique index failed")
 	}
 }
+
+type ExcludedColumnIndex struct {
+	ID      int64
+	Email   string `sql:"unique_index:uix_excluded_column_index_email"`
+	Deleted bool   `sql:"unique_index:!uix_excluded_column_index_email"`
+}
+
+func TestConditionalIndexExcludesColumn(t *testing.T) {
+	// This behavior is only supported for DBMSes that support partial indices
+	// (i.e., not MySQL).
+	dialect := os.Getenv("GORM_DIALECT")
+	switch dialect {
+	case "", "sqlite", "postgres", "mssql":
+	default:
+		return
+	}
+
+	if err := DB.DropTableIfExists(&ExcludedColumnIndex{}).Error; err != nil {
+		fmt.Printf("Got error when try to delete table excluded_column_index, %+v\n", err)
+	}
+
+	if err := DB.AutoMigrate(&ExcludedColumnIndex{}).Error; err != nil {
+		t.Errorf("Failed to migrate: %+v", err)
+	}
+
+	if err := DB.Save(&ExcludedColumnIndex{Email: "impl@example.com"}).Error; err != nil {
+		t.Errorf("Unexpected error saving first entry: %v", err)
+	}
+
+	if err := DB.Save(&ExcludedColumnIndex{Email: "impl@example.com"}).Error; err == nil {
+		t.Error("Unique index was not created")
+	}
+
+	var u ExcludedColumnIndex
+	if err := DB.First(&u).Error; err != nil {
+		t.Errorf("Enexpected error retrieving first entry: %v", err)
+	}
+
+	u.Deleted = true
+	if err := DB.Save(&u).Error; err != nil {
+		t.Errorf("Unexpected error saving first entry: %v", err)
+	}
+
+	if err := DB.Save(&ExcludedColumnIndex{Email: "impl@example.com"}).Error; err != nil {
+		t.Errorf("Conditional index failed: %v", err)
+	}
+}

scope.go

@@ -1185,40 +1185,81 @@ func (scope *Scope) autoMigrate() *Scope {
 	return scope
 }
 
+type derivedIndex struct {
+	columns []string
+	q       *DB
+}
+
 func (scope *Scope) autoIndex() *Scope {
-	var indexes = map[string][]string{}
+	indexes := map[string]map[string]*derivedIndex{
-	var uniqueIndexes = map[string][]string{}
+		"INDEX":        make(map[string]*derivedIndex),
+		"UNIQUE_INDEX": make(map[string]*derivedIndex),
+	}
+
+	derive := func(field *StructField, tag, prefix string) {
+		if name, ok := field.TagSettings[tag]; ok {
+			names := strings.Split(name, ",")
+
+			for _, name := range names {
+				exclude := false
+
+				if name == tag || name == "" {
+					name = fmt.Sprintf("%s_%v_%v", prefix, scope.TableName(), field.DBName)
+				} else if name[0] == '!' {
+					exclude = true
+					name = name[1:]
+				}
+
+				idx, ok := indexes[tag][name]
+				if !ok {
+					idx = &derivedIndex{q: scope.NewDB().Model(scope.Value)}
+					indexes[tag][name] = idx
+				}
+
+				if exclude {
+					// We can't just bind this; most (all?) DBMSes don't seem
+					// to support parameterizing partial indices.
+					f, _ := scope.FieldByName(field.Name)
+					v, _ := driver.DefaultParameterConverter.ConvertValue(reflect.Zero(f.Field.Type()).Interface())
+
+					// Possibilities are limited:
+					// https://golang.org/pkg/database/sql/driver/#Value
+					cond := "IS NULL"
+					switch value := v.(type) {
+					case int64, float64:
+						cond = "= 0"
+					case bool:
+						switch scope.Dialect().DataTypeOf(field) {
+						case "bool", "boolean":
+							cond = "= false"
+						default:
+							cond = "= 0"
+						}
+					case []byte, string:
+						cond = "= ''"
+					case time.Time:
+						cond = fmt.Sprintf("= '%s'", value.Format(time.RFC3339))
+					}
+
+					idx.q = idx.q.Where(fmt.Sprintf("%s %s", scope.Quote(field.DBName), cond))
+				} else {
+					idx.columns = append(idx.columns, field.DBName)
+				}
+			}
+		}
+	}
 
 	for _, field := range scope.GetStructFields() {
-		if name, ok := field.TagSettings["INDEX"]; ok {
+		derive(field, "INDEX", "idx")
-			names := strings.Split(name, ",")
+		derive(field, "UNIQUE_INDEX", "uix")
-
-			for _, name := range names {
-				if name == "INDEX" || name == "" {
-					name = fmt.Sprintf("idx_%v_%v", scope.TableName(), field.DBName)
-				}
-				indexes[name] = append(indexes[name], field.DBName)
-			}
-		}
-
-		if name, ok := field.TagSettings["UNIQUE_INDEX"]; ok {
-			names := strings.Split(name, ",")
-
-			for _, name := range names {
-				if name == "UNIQUE_INDEX" || name == "" {
-					name = fmt.Sprintf("uix_%v_%v", scope.TableName(), field.DBName)
-				}
-				uniqueIndexes[name] = append(uniqueIndexes[name], field.DBName)
-			}
-		}
 	}
 
-	for name, columns := range indexes {
+	for name, idx := range indexes["INDEX"] {
-		scope.NewDB().Model(scope.Value).AddIndex(name, columns...)
+		idx.q.AddIndex(name, idx.columns...)
 	}
 
-	for name, columns := range uniqueIndexes {
+	for name, idx := range indexes["UNIQUE_INDEX"] {
-		scope.NewDB().Model(scope.Value).AddUniqueIndex(name, columns...)
+		idx.q.AddUniqueIndex(name, idx.columns...)
 	}
 
 	return scope