(WIP) Implement Generics API

callbacks/preload.go

@@ -275,6 +275,8 @@ func preload(tx *gorm.DB, rel *schema.Relationship, conds []interface{}, preload
 	column, values := schema.ToQueryValues(clause.CurrentTable, relForeignKeys, foreignValues)
 
 	if len(values) != 0 {
+		tx = tx.Model(reflectResults.Addr().Interface()).Where(clause.IN{Column: column, Values: values})
+
 		for _, cond := range conds {
 			if fc, ok := cond.(func(*gorm.DB) *gorm.DB); ok {
 				tx = fc(tx)
@@ -283,7 +285,11 @@ func preload(tx *gorm.DB, rel *schema.Relationship, conds []interface{}, preload
 			}
 		}
 
-		if err := tx.Where(clause.IN{Column: column, Values: values}).Find(reflectResults.Addr().Interface(), inlineConds...).Error; err != nil {
+		if len(inlineConds) > 0 {
+			tx = tx.Where(inlineConds[0], inlineConds[1:]...)
+		}
+
+		if err := tx.Find(reflectResults.Addr().Interface()).Error; err != nil {
 			return err
 		}
 	}

callbacks/query.go

@@ -146,9 +146,13 @@ func BuildQuerySQL(db *gorm.DB) {
 
 					if isRelations {
 						genJoinClause := func(joinType clause.JoinType, parentTableName string, relation *schema.Relationship) clause.Join {
-							tableAliasName := relation.Name
-							if parentTableName != clause.CurrentTable {
-								tableAliasName = utils.NestedRelationName(parentTableName, tableAliasName)
+							tableAliasName := join.Alias
+
+							if tableAliasName == "" {
+								tableAliasName = relation.Name
+								if parentTableName != clause.CurrentTable {
+									tableAliasName = utils.NestedRelationName(parentTableName, tableAliasName)
+								}
 							}
 
 							columnStmt := gorm.Statement{
@@ -167,6 +171,13 @@ func BuildQuerySQL(db *gorm.DB) {
 								}
 							}
 
+							if join.Expression != nil {
+								return clause.Join{
+									Type:       join.JoinType,
+									Expression: join.Expression,
+								}
+							}
+
 							exprs := make([]clause.Expression, len(relation.References))
 							for idx, ref := range relation.References {
 								if ref.OwnPrimaryKey {

chainable_api.go

@@ -448,9 +448,10 @@ func (db *DB) Assign(attrs ...interface{}) (tx *DB) {
 // Unscoped allows queries to include records marked as deleted,
 // overriding the soft deletion behavior.
 // Example:
-//    var users []User
-//    db.Unscoped().Find(&users)
-//    // Retrieves all users, including deleted ones.
+//
+//	var users []User
+//	db.Unscoped().Find(&users)
+//	// Retrieves all users, including deleted ones.
 func (db *DB) Unscoped() (tx *DB) {
 	tx = db.getInstance()
 	tx.Statement.Unscoped = true

clause/joins.go

@@ -1,5 +1,7 @@
 package clause
 
+import "gorm.io/gorm/utils"
+
 type JoinType string
 
 const (
@@ -9,6 +11,30 @@ const (
 	RightJoin JoinType = "RIGHT"
 )
 
+type JoinTarget struct {
+	Type        JoinType
+	Association string
+	Subquery    Expression
+	Table       string
+}
+
+func Has(name string) JoinTarget {
+	return JoinTarget{Type: InnerJoin, Association: name}
+}
+
+func (jt JoinType) Association(name string) JoinTarget {
+	return JoinTarget{Type: jt, Association: name}
+}
+
+func (jt JoinType) AssociationFrom(name string, subquery Expression) JoinTarget {
+	return JoinTarget{Type: jt, Association: name, Subquery: subquery}
+}
+
+func (jt JoinTarget) As(name string) JoinTarget {
+	jt.Table = name
+	return jt
+}
+
 // Join clause for from
 type Join struct {
 	Type       JoinType
@@ -18,6 +44,12 @@ type Join struct {
 	Expression Expression
 }
 
+func JoinTable(names ...string) Table {
+	return Table{
+		Name: utils.JoinNestedRelationNames(names),
+	}
+}
+
 func (join Join) Build(builder Builder) {
 	if join.Expression != nil {
 		join.Expression.Build(builder)