I have two entity, first one is User:

// User holds the schema definition for the User entity.
type User struct {
    ent.Schema
}

// Annotation of the User.
func (User) Annotations() []schema.Annotation {
    return []schema.Annotation{
        entsql.Annotation{Table: "user"},
        entsql.WithComments(true),
    }
}

// Fields of the User.
func (User) Fields() []ent.Field {
    return []ent.Field{
        field.String("nickname").NotEmpty(),
                ...
    }
}

// Edges of the User.
func (User) Edges() []ent.Edge {
    return []ent.Edge{
        edge.To("took_exams", Exam.Type).Through("exam_results", ExamResult.Type),
    }
}

second one is Exam

// Exam holds the schema definition for the Exam entity.
type Exam struct {
    ent.Schema
}

// Annotation of the Exam.
func (Exam) Annotations() []schema.Annotation {
    return []schema.Annotation{
        entsql.Annotation{Table: "exam"},
        entsql.WithComments(true),
    }
}

// Fields of the Exam.
func (Exam) Fields() []ent.Field {
    return []ent.Field{
        field.String("name").NotEmpty(),
            ...
    }
}

// Edges of the Exam.
func (Exam) Edges() []ent.Edge {
    return []ent.Edge{
        edge.From("exam_users", User.Type).Ref("took_exams").Through("exam_results", ExamResult.Type),
    }
}

User can take exam more then 1 time, so I have a separate table to record user exam histories :

// ExamResult holds the schema definition for the ExamResult entity.
type ExamResult struct {
    ent.Schema
}

// Annotations of the ExamResult.
func (ExamResult) Annotations() []schema.Annotation {
    return []schema.Annotation{
        field.ID("user_id", "exam_id", "times"),
        entsql.Table("exam_result"),
        entsql.WithComments(true),
    }
}

// Fields of the ExamResult.
func (ExamResult) Fields() []ent.Field {
    return []ent.Field{
        field.Int("user_id"),
        field.Int("exam_id"),
        field.Int("times"),
        field.Int("score"),
        ...
    }
}

// Edges of the ExamResult.
func (ExamResult) Edges() []ent.Edge {
    return []ent.Edge{
        edge.To("user", User.Type).Field("user_id").Unique().Required(),
        edge.To("exam", Exam.Type).Field("exam_id").Unique().Required(),
    }
}

I want to use user_id 、exam_id and times to be indexes. but when I run generate error comes out edge schema primary key can only be defined on "id" or ("user_id", "exam_id") in the same order .
is there sth notices I missed?

I want the exam_record table record user’s everytime exam result.

how can i achieve this in ent framework.