Add join assoc query builder (#298)

query.go

@@ -182,6 +182,18 @@ func (q Query) Joinf(expr string, args ...interface{}) Query {
 	return q
 }
 
+// JoinAssoc current table with other table based on association field.
+func (q Query) JoinAssoc(assoc string, filter ...FilterQuery) Query {
+	return q.JoinAssocWith("JOIN", assoc, filter...)
+}
+
+// JoinAssocWith current table with other table based on association field.
+func (q Query) JoinAssocWith(mode string, assoc string, filter ...FilterQuery) Query {
+	NewJoinAssocWith(mode, assoc, filter...).Build(&q)
+
+	return q
+}
+
 // Where query.
 func (q Query) Where(filters ...FilterQuery) Query {
 	q.WhereQuery = q.WhereQuery.And(filters...)
@@ -467,6 +479,21 @@ func JoinWith(mode string, table string, from string, to string, filter ...Filte
 	return query
 }
 
+// JoinAssoc create a query with chainable syntax, using join as the starting point.
+func JoinAssoc(assoc string, filter ...FilterQuery) Query {
+	return JoinAssocWith("JOIN", assoc, filter...)
+}
+
+// JoinAssocWith create a query with chainable syntax, using join as the starting point.
+func JoinAssocWith(mode string, assoc string, filter ...FilterQuery) Query {
+	query := newQuery()
+	query.JoinQuery = []JoinQuery{
+		NewJoinAssocWith(mode, assoc, filter...),
+	}
+	query.AddPopulator(&query.JoinQuery[0])
+	return query
+}
+
 // Joinf create a query with chainable syntax, using join as the starting point.
 func Joinf(expr string, args ...interface{}) Query {
 	query := newQuery()

query_test.go

@@ -377,6 +377,29 @@ func TestQuery_Joinf(t *testing.T) {
 	shallowAssertQuery(t, result, rel.Joinf("JOIN transactions ON transacations.id=?", 1).From("users"))
 }
 
+func TestQuery_JoinAssoc(t *testing.T) {
+	result := rel.Query{
+		Table: "users",
+		JoinQuery: []rel.JoinQuery{
+			{
+				Mode:  "JOIN",
+				Table: "transactions",
+				To:    "transactions.user_id",
+				From:  "users.id",
+				Assoc: "transactions",
+			},
+		},
+		CascadeQuery: true,
+	}
+
+	shallowAssertQuery(t, result,
+		rel.Build("", rel.From("users").JoinAssoc("transactions")).
+			Populate(rel.NewDocument(&rel.User{}, false).Meta()))
+	shallowAssertQuery(t, result,
+		rel.Build("users", rel.JoinAssoc("transactions")).
+			Populate(rel.NewDocument(&rel.User{}, false).Meta()))
+}
+
 func TestQuery_Where(t *testing.T) {
 	tests := []struct {
 		Case     string