Merge pull request #11 from dipdup-io/hasura-relations

Hasura: add relationships

Author: aopoltorzhicky

hasura/hasura.go

@@ -199,9 +199,80 @@ func generateOne(hasura config.Hasura, schema string, model interface{}) (table,
 
 	t.HasuraSchema.SelectPermissions = append(t.HasuraSchema.SelectPermissions, formatSelectPermissions(hasura.RowsLimit, hasura.EnableAggregations, t.Columns...))
 
+	if err := getRelationships(&t.HasuraSchema, t.Name, typ); err != nil {
+		return t, err
+	}
+
 	return t, nil
 }
 
+type rel struct {
+	tableName   string
+	remoteField string
+	field       string
+	name        string
+	typ         string
+	comment     string
+}
+
+func getRelationships(t *Table, name string, typ reflect.Type) error {
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		tag := field.Tag.Get("hasura")
+		if tag == "" {
+			continue
+		}
+
+		var r rel
+		attrs := strings.Split(tag, ",")
+		for i := range attrs {
+			keyValue := strings.Split(attrs[i], ":")
+			if len(keyValue) != 2 {
+				return errors.Errorf("invalid hasura tag: %s", tag)
+			}
+			switch keyValue[0] {
+			case "table":
+				r.tableName = keyValue[1]
+			case "field":
+				r.field = keyValue[1]
+			case "type":
+				r.typ = keyValue[1]
+			case "name":
+				r.name = keyValue[1]
+			case "comment":
+				r.comment = keyValue[1]
+			case "remote_field":
+				r.remoteField = keyValue[1]
+			}
+		}
+
+		relationship := Relationship{
+			Table: PGTable{
+				Name: name,
+			},
+			Name:    r.name,
+			Comment: r.comment,
+			Using: RelationshipUsing{
+				Manual: &ManualRelationship{
+					RemoteTable: PGTable{Name: r.tableName},
+					ColumnMapping: map[string]string{
+						r.field: r.remoteField,
+					},
+				},
+			},
+		}
+
+		switch r.typ {
+		case "oto":
+			t.ObjectRelationships = append(t.ObjectRelationships, relationship)
+		case "otm", "mtm":
+			t.ArrayRelationships = append(t.ArrayRelationships, relationship)
+		}
+	}
+
+	return nil
+}
+
 func formatSelectPermissions(limit uint64, allowAggs bool, columns ...string) SelectPermission {
 	if limit == 0 {
 		limit = 10

hasura/requests.go

@@ -87,17 +87,69 @@ type Source struct {
 
 // Table -
 type Table struct {
-	ObjectRelationships []interface{}      `json:"object_relationships"`
-	ArrayRelationships  []interface{}      `json:"array_relationships"`
+	ObjectRelationships []Relationship     `json:"object_relationships"`
+	ArrayRelationships  []Relationship     `json:"array_relationships"`
 	SelectPermissions   []SelectPermission `json:"select_permissions"`
 	Configuration       TableConfiguration `json:"configuration"`
 	Schema              TableSchema        `json:"table"`
 }
 
+// Relationship -
+type Relationship struct {
+	Table   PGTable           `json:"table"`
+	Name    string            `json:"name"`
+	Comment string            `json:"comment,omitempty"`
+	Using   RelationshipUsing `json:"using"`
+}
+
+// RelationshipUsing -
+type RelationshipUsing struct {
+	Manual *ManualRelationship `json:"manual_configuration,omitempty"`
+	FK     *FKRelationship     `json:"foreign_key_constraint_on,omitempty"`
+}
+
+// PGTable -
+type PGTable struct {
+	Name   string `json:"name"`
+	Schema string `json:"schema"`
+}
+
+// UnmarshalJSON -
+func (t *PGTable) UnmarshalJSON(data []byte) error {
+	type buf PGTable
+	if err := json.Unmarshal(data, (*buf)(t)); err == nil {
+		return err
+	}
+
+	return json.Unmarshal(data, &t.Name)
+}
+
+// MarshalJSON -
+func (t *PGTable) MarshalJSON() ([]byte, error) {
+	if t.Schema == "" {
+		return json.Marshal(t.Name)
+	}
+
+	type buf PGTable
+	return json.Marshal((*buf)(t))
+}
+
+// ManualRelationship -
+type ManualRelationship struct {
+	RemoteTable   PGTable           `json:"remote_table"`
+	ColumnMapping map[string]string `json:"column_mapping"`
+}
+
+// FKRelationship -
+type FKRelationship struct {
+	Table  string `json:"table"`
+	Column string `json:"column"`
+}
+
 func newMetadataTable(name, schema string) Table {
 	return Table{
-		ObjectRelationships: make([]interface{}, 0),
-		ArrayRelationships:  make([]interface{}, 0),
+		ObjectRelationships: make([]Relationship, 0),
+		ArrayRelationships:  make([]Relationship, 0),
 		SelectPermissions:   make([]SelectPermission, 0),
 		Schema: TableSchema{
 			Name:   name,