constraint.decorator.ts

import { Neo4jMetadataStorage } from '../storage';

/**
 * See Neo4j constraint documentation for details:
 *
 * https://neo4j.com/docs/cypher-manual/current/constraints/
 */
export type ConstraintOptions = {
  name?: string;
  ifNotExists?: boolean;
  additionalKeys?: string[];
  useCommonName?: boolean;
};

export function Constraint(
  constraintType: string,
  options?: ConstraintOptions,
): PropertyDecorator {
  return (target: Object, propertyKey: string | symbol) => {
    Neo4jMetadataStorage.addPropertyConstraint({
      target: target.constructor,
      property: propertyKey.toString(),
      constraintType,
      options: {
        ...options,
        ifNotExists: options?.ifNotExists !== false,
        useCommonName: options?.useCommonName !== false,
      },
    });
  };
}

/**
 * Node key constraints.
 *
 * Node key constraints ensure that, for a given label and set of properties:
 *   All the properties exist on all the nodes with that label.
 *   The combination of the property values is unique.
 *
 *   CREATE CONSTRAINT FOR (p:Person) REQUIRE (p.firstname, p.surname) IS NODE KEY
 *   CREATE CONSTRAINT node_key FOR (p:Person) REQUIRE p.firstname IS NODE KEY
 */
export function NodeKey(options?: ConstraintOptions): PropertyDecorator {
  return Constraint('IS NODE KEY', options);
}

/**
 * Unique node property constraints.
 *
 * Unique property constraints ensure that property values are unique for all nodes with a specific label.
 * For unique property constraints on multiple properties, the combination of the property values is unique.
 * Unique constraints do not require all nodes to have a unique value for the properties listed—nodes without all properties are not subject to this rule.
 *
 *   CREATE CONSTRAINT FOR (p:Person) REQUIRE p.name IS UNIQUE
 *   CREATE CONSTRAINT uniqueness FOR (p:Person) REQUIRE (p.firstname, p.age) IS UNIQUE
 *
 * Queries attempting to do any of the following will fail:
 *  - Create new nodes without all the properties or where the combination of property values is not unique.
 *  - Remove one of the mandatory properties.
 *  - Update the properties so that the combination of property values is no longer unique.
 */
export function Unique(options?: ConstraintOptions): PropertyDecorator {
  return Constraint('IS UNIQUE', options);
}

/**
 * - Node property existence constraints.
 *
 * Node property existence constraints ensure that a property exists for all nodes with a specific label.
 * Queries that try to create new nodes of the specified label, but without this property, will fail.
 * The same is true for queries that try to remove the mandatory property.
 *
 *   CREATE CONSTRAINT FOR (p:Person) REQUIRE p.name IS NOT NULL
 *   CREATE CONSTRAINT node_exists IF NOT EXISTS FOR (p:Person) REQUIRE p.name IS NOT NULL * @param options
 *
 * - Relationship property existence constraints
 * Property existence constraints ensure that a property exists for all relationships with a specific type.
 * All queries that try to create relationships of the specified type, but without this property, will fail.
 * The same is true for queries that try to remove the mandatory property.
 *
 *   CREATE CONSTRAINT FOR ()-[l:LIKED]-() REQUIRE l.when IS NOT NULL
 *   CREATE CONSTRAINT relationship_exists FOR ()-[l:LIKED]-() REQUIRE l.since IS NOT NULL
 */
export function NotNull(
  options?: Omit<ConstraintOptions, 'additionalKeys'>,
): PropertyDecorator {
  return Constraint('IS NOT NULL', options);
}