@sap/eslint-plugin-cds/lib/rules/no-dollar-prefixed-names.js

ESLint plugin including recommended SAP Cloud Application Programming model and environment rules

'use strict'

const { RULE_CATEGORIES } = require('../constants')

/**
 * Util to check if an entity is part of an external service.
 */
class ExternalServices {
  hasExternalServices = false
  externalServices = Object.create(null)

  static create(model) {
    return new ExternalServices(model)
  }

  constructor(model) {
    for (const defName in model.definitions) {
      const def = model.definitions[defName]
      if (def?.kind === 'service' && def['@cds.external']) {
        this.externalServices[defName] = true
        this.hasExternalServices = true
      }
    }
  }

  isInExternalService(defName) {
    if (!this.hasExternalServices)
      return false // shortcut
    const segments = defName.split('.')
    for (let i = segments.length - 1; i >= 0; i--)
      if (this.externalServices[segments.slice(0, i).join('.')])
        return true
    return false
  }

}

module.exports = {
  meta: {
    schema: [{/* to avoid deprecation warning for ESLint 9 */}],
    docs: {
      category: RULE_CATEGORIES.model,
      description: 'Names must not start with $ to avoid possible shadowing of reserved variables.',
      recommended: true,
      url: 'https://cap.cloud.sap/docs/tools/cds-lint/rules/no-dollar-prefixed-names',
    },
    messages: {
      dollarPrefix: `'{{name}}' is prefixed with a dollar sign ($)`,
    },
    type: 'problem'
  },

  create(context) {
    const model = context.getModel()
    if (!model?.definitions)
      return

    const externals = ExternalServices.create(model)

    return function checkAllElementsForDollarPrefix() {
      for (const defName in model.definitions) {
        if (!externals.isInExternalService(defName))
          checkElements(defName, model.definitions[defName])
      }
    }

    function checkElements(defName, def) {
      if (!Object.hasOwn(def,'elements') || !def.elements || typeof def.elements !== 'object')
        return

      for (const elementName in def.elements) {
        const element = def.elements[elementName]
        check(elementName, element)
        if (element.elements)
          checkElements(elementName, element)
      }
    }

    function check(name, def) {
      if (name.startsWith('$')) {
        context.report({
          messageId: 'dollarPrefix',
          data: { name },
          loc: context.getLocation(name, def, model),
        })
      }
    }
  }
}