add runtime deprecation warning

CHANGELOG.md

@@ -135,7 +135,7 @@ ___
 - Fix incorrect LiveQuery events triggered for multiple subscriptions on the same class with different events [#7341](https://github.com/parse-community/parse-server/pull/7341)
 - Fix select and excludeKey queries to properly accept JSON string arrays. Also allow nested fields in exclude (Corey Baker) [#7242](https://github.com/parse-community/parse-server/pull/7242)
 - Fix LiveQuery server crash when using $all query operator on a missing object key (Jason Posthuma) [#7421](https://github.com/parse-community/parse-server/pull/7421)
-
+- Added runtime deprecation warnings (Manuel Trezza) [#7451](https://github.com/parse-community/parse-server/pull/7451)
 ___
 ## 4.5.0
 [Full Changelog](https://github.com/parse-community/parse-server/compare/4.4.0...4.5.0)

CONTRIBUTING.md

@@ -182,7 +182,9 @@ If you change or remove an existing feature that would lead to a breaking change
   - Use a default value that falls back to existing behavior.
   - Add a deprecation definition in `Deprecator/Deprecations.js` that will output a deprecation warning log message on Parse Server launch, for example:
     > DeprecationWarning: The Parse Server option 'example' will be removed in a future release.
-
+
+For deprecations that can only be determined ad-hoc during runtime, for example Parse Query syntax deprecations, use the `Deprecator.logRuntimeDeprecation()` method.
+
 Deprecations become breaking changes after notifying developers through deprecation warnings for at least one entire previous major release. For example:
   - `4.5.0` is the current version
   - `4.6.0` adds a new optional feature and a deprecation warning for the existing feature

spec/Deprecator.spec.js

@@ -21,16 +21,28 @@ describe('Deprecator', () => {
     const logSpy = spyOn(logger, 'warn').and.callFake(() => {});
 
     await reconfigureServer();
-    expect(logSpy.calls.all()[0].args[0]).toContain(deprecations[0].optionKey);
-    expect(logSpy.calls.all()[0].args[0]).toContain(deprecations[0].changeNewDefault);
+    expect(logSpy.calls.all()[0].args[0]).toEqual(
+      `DeprecationWarning: The Parse Server option '${deprecations[0].optionKey}' default will change to '${deprecations[0].changeNewDefault}' in a future version.`
+    );
   });
 
   it('does not log deprecation for new default if option is set manually', async () => {
     deprecations = [{ optionKey: 'exampleKey', changeNewDefault: 'exampleNewDefault' }];
 
     spyOn(Deprecator, '_getDeprecations').and.callFake(() => deprecations);
-    const logSpy = spyOn(Deprecator, '_log').and.callFake(() => {});
+    const logSpy = spyOn(Deprecator, '_logOption').and.callFake(() => {});
     await reconfigureServer({ [deprecations[0].optionKey]: 'manuallySet' });
     expect(logSpy).not.toHaveBeenCalled();
   });
+
+  it('logs runtime deprecation', async () => {
+    const logger = require('../lib/logger').logger;
+    const logSpy = spyOn(logger, 'warn').and.callFake(() => {});
+    const options = { usage: 'Doing this', solution: 'Do that instead.' };
+
+    Deprecator.logRuntimeDeprecation(options);
+    expect(logSpy.calls.all()[0].args[0]).toEqual(
+      `DeprecationWarning: ${options.usage} is deprecated and will be removed in a future version. ${options.solution}`
+    );
+  });
 });

src/Deprecator/Deprecator.js

@@ -22,11 +22,41 @@ class Deprecator {
 
       // If default will change, only throw a warning if option is not set
       if (changeNewDefault != null && options[optionKey] == null) {
-        Deprecator._log({ optionKey, changeNewDefault, solution });
+        Deprecator._logOption({ optionKey, changeNewDefault, solution });
       }
     }
   }
 
+  /**
+   * Logs a deprecation warning for a parameter that can only be determined dynamically
+   * during runtime.
+   *
+   * Note: Do not use this to log deprecations of Parse Server options, but add such
+   * deprecations to `Deprecations.js` instead. See the contribution docs for more
+   * details.
+   *
+   * For consistency, the deprecation warning is composed of the following parts:
+   *
+   * > DeprecationWarning: `usage` is deprecated and will be removed in a future version.
+   * `solution`.
+   *
+   * - `usage`: The deprecated usage.
+   * - `solution`: The instruction to resolve this deprecation warning.
+   *
+   * For example:
+   * > DeprecationWarning: `Prefixing field names with dollar sign ($) in aggregation query`
+   * is deprecated and will be removed in a future version. `Reference field names without
+   * dollar sign prefix.`
+   *
+   * @param {Object} options The deprecation options.
+   * @param {String} options.usage The usage that is deprecated.
+   * @param {String} [options.solution] The instruction to resolve this deprecation warning.
+   * Optional. It is recommended to add an instruction for the convenience of the developer.
+   */
+  static logRuntimeDeprecation(options) {
+    Deprecator._logGeneric(options);
+  }
+
   /**
    * Returns the deprecation definitions.
    * @returns {Array<Object>} The deprecations.
@@ -35,8 +65,24 @@ class Deprecator {
     return Deprecations;
   }
 
+  /**
+   * Logs a generic deprecation warning.
+   *
+   * @param {Object} options The deprecation options.
+   * @param {String} options.usage The usage that is deprecated.
+   * @param {String} [options.solution] The instruction to resolve this deprecation warning.
+   * Optional. It is recommended to add an instruction for the convenience of the developer.
+   */
+  static _logGeneric({ usage, solution }) {
+    // Compose message
+    let output = `DeprecationWarning: ${usage} is deprecated and will be removed in a future version.`;
+    output += solution ? ` ${solution}` : '';
+    logger.warn(output);
+  }
+
   /**
    * Logs a deprecation warning for a Parse Server option.
+   *
    * @param {String} optionKey The option key incl. its path, e.g. `security.enableCheck`.
    * @param {String} envKey The environment key, e.g. `PARSE_SERVER_SECURITY`.
    * @param {String} changeNewKey Set the new key name if the current key will be replaced,
@@ -48,7 +94,7 @@ class Deprecator {
    * automatically added to the message. It should only contain the instruction on how
    * to resolve this warning.
    */
-  static _log({ optionKey, envKey, changeNewKey, changeNewDefault, solution }) {
+  static _logOption({ optionKey, envKey, changeNewKey, changeNewDefault, solution }) {
     const type = optionKey ? 'option' : 'environment key';
     const key = optionKey ? optionKey : envKey;
     const keyAction =