Attribute Rules Manager
ArcGIS-style Attribute Rules (calculation, constraint, validation) for GeoPackage, SpatiaLite and File Geodatabase layers.
Define attribute rules once and let QGIS apply them while you edit. Calculation rules fill a field automatically (area, coordinates, next ID, date, editor, values from other layers) when a feature is created or edited. Constraint rules must be true, otherwise the feature form refuses to save, and edits made on the map that break a strict rule are undone (for example: a point must not be drawn inside a polygon layer). Validation rules check existing data on demand and select the features with problems. Rules are QGIS expressions with ready-made templates, stored inside the data file so they travel with it, and applied automatically whenever the layers are loaded.