feat: implement database handlerImplement a database api to manage nodes and relationships in a "graph databaselike" implemented in sqlite.closes #1

pkg/relationship.go

@@ -0,0 +1,50 @@
+package synchronizator
+
+// A user representation of a relationship, this interface should be implemented by the user
+// to provide the ability to parse the database relationship into a user defined
+// struct that fulfills it's requirements.
+//
+// Example usage:
+//
+//	type collection_relation struct{}
+//
+//	func (collection *collection_relation) ToRelationship() (string, []byte, error) {
+//		return "COLLECTION_HAS", nil, nil
+//	}
+//
+//	func (collection *collection_relation) FromRelationship(_class string, metadata []byte) error {
+//		if _class != "COLLECTION_HAS" {
+//			return fmt.Errorf("invalid class %s", _class)
+//		}
+//		return nil
+//	}
+type RelationshipClass interface {
+	// How to transform the struct into a collection. It needs to return the class,
+	// and a []byte representation of the metadata.
+	//
+	// - class: Is used for classification and query pourposes. It's recomended to provide a constante string to increase consistency.
+	// - metadata: Arbitrary data. This will be stored as a jsonb in the database
+	//
+	ToRelationship() (string, []byte, error)
+
+	// How to transform a relationship into the struct. This method should modify the
+	// struct directly as it receives a pointer.
+	//
+	// - class: Is used for classification and query pourposes.
+	// - metadata: Arbitrary data. This is stored as a jsonb in the database
+	FromRelationship(string, []byte) error
+}
+
+// A relationship in the database.
+// It adds some helper methods to easily manage the node.
+type Relationship struct {
+	_conn    *DB    // Underlaying connection to the database.
+	_class   string // The class of the node, should not be modified to avoid inconsistencies.
+	From     int64  // From what node this relation comes from
+	To       int64  // To what node this relation goes to
+	Metadata []byte // Arbitrary data. This is stored as a jsonb in the database
+}
+
+func (relationship *Relationship) GetClass() string {
+	return relationship._class
+}