@sap/cds-compiler/lib/checks/manyExpand.js

CDS (Core Data Services) compiler and backends

'use strict';

const { applyTransformationsOnNonDictionary } = require('../model/csnUtils');

/**
 * Check for nested projections (expand) on to-many associations or compositions.
 * Nested projections are only valid for to-one relationships.
 *
 * @param {object} parent Object with the expression as a property
 * @param {string} propOnParent Name of the expression property on parent
 * @param {Array} _e Expression to check (unused)
 * @param {CSN.Path} path
 */
function expandToMany( parent, propOnParent, _e, path ) {
  applyTransformationsOnNonDictionary(parent, propOnParent, {
    expand: (_parent, _prop, _expand, _path) => {
      const last = _parent._links?.at(-1).art;
      if (last?.cardinality && last.cardinality.max !== 1) {
        this.message('ref-unexpected-many-expand', _path,
                     { '#': last.type === 'cds.Composition' ? 'composition' : 'std' });
      }
    },
  }, null, path);
}

module.exports = {
  columns: expandToMany,
};