loopback/3.0-RELEASE-NOTES.md

List of notable changes made between 2.x and 3.0

All breaking changes must be described here. When adding a new entry, always describe the impact on users and instructions for upgrading applications from 2.x to 3.0.

loopback-datasource-juggler was moved from peerDependencies to dependencies

Originally, we (ab)used peer dependencies to ensure there is only one instance of loopback-datasource-juggler in the dependency tree, so that there is only one singleton instance of model registry. This was very fragile and might not have worked in certain edge cases.

We have reworked loopback-datasource-juggler and connectors to not rely on a single juggler instance anymore. As the last step, juggler became a regular dependency.

https://github.com/strongloop/loopback/issues/275

When upgrading application from previous loopback versions, simply remove loopback-datasource-juggler from your dependencies.

always use bluebird as promise library

In version 3.0, we always use bluebird as our promise library instead of global.Promise. We consider Bluebird API a part of LoopBack API from now on, you are welcome to use any Bluebird-specific methods in your applications.

If you are using LoopBack with a custom promise implementation provided via global.Promise, you will have to check all places where you are using non-standard promise API and update them to use Bluebird API instead.

Please see Related code change here.

new method of defining remoting metadata

In 2.0, remote methods were defined as:

methods: {
  staticMethod: {
    isStatic: true,
    http: { path: '/static' }
  },
  instanceMethod: {
    isStatic: false,
    http: { path: '/instance' }
  }
}

For 3.0, the isStatic flag is no longer required and will be determined from the method name. Method name starting with "prototype." will be the same as having isStatic flag set to false.

methods: {
  staticMethod: {
    http: { path: '/static' }
  },
  'prototype.instanceMethod': {
  http: { path: '/instance' }
}

Please see related code change here.

remove Change.handleError

Change.handleError is now removed as it was used inconsistenly for a subset of possible errors only. All Change methods will report all errors to the caller via the callback.

Use PersistedModel to report change-tracking errors via the existing method PersistedModel.handleChangeError. This method can be customized on a per-model basis to provide different error handling.

Please see related code change here.

remove unused user properties

The following properties are removed from the built-in User model in 3.0:

• credentials
• challenges
• status
• created
• lastUpdated

Developers that are relying on these properties, can redefine them in user.json or equivalent model.json as follow:

{
  "name": "MyUser",
  "base": "User",
  "properties": {
    "credentials": { "type": "object" },
    "challenges": { "type": "object" },
    "status": "string",
    "created": "date",
    "lastUpdated": "date"
  }
}

Please see Related code change here.

Remove getters for Express 3.x middleware

Express 4.x stopped bundling commonly-used middleware. To simplify migration of LoopBack 1.x applications (powered by Express 3.x) to LoopBack 2.x (powered by Express 4.x), we created getter properties to allow developers to keep using the old convention.

We have removed these getters in LoopBack 3.0, here is the full list of removed properties together with the middleware module name to use instead:

• loopback.compress - use require('compression') instead
• loopback.timeout - use require('connect-timeout') instead
• loopback.cookieParser - use require('cookie-parser') instead
• loopback.cookieSession - use require('cookie-session') instead
• loopback.csrf - use require('csurf') instead
• loopback.errorHandler - use require('errorhandler') instead
• loopback.session - use require('express-session') instead
• loopback.methodOverride - use require('method-override') instead
• loopback.logger - use require('morgan') instead
• loopback.responseTime - use require('response-time') instead
• loopback.favicon - use require('serve-favicon') instead
• loopback.directory - use require('serve-index') instead
• loopback.vhost - use require('vhost') instead

We have also removed loopback.mime, which was always set to undefined.

See loopback#2349.

Remove loopback#errorhandler

We have removed loopback#errorhandler middleware, users should use strong-error-handler directly.

// server/middleware.json
{
  // ...
  "final:after": {
    "strong-error-handler": {}
  }
}

// server/middleware.development.json
{
  "final:after": {
    "strong-error-handler": {
      "params": {
        "debug": true
      }
  }
}

See also strong-error-handler's options and the related code change.

Remove current context API and middleware

We have removed the following current-context-related APIs:

• loopback.getCurrentContext
• loopback.createContext
• loopback.runInContext

Additionally, loopback#context middleware and remoting.context server config were removed too.

Upgrading from 2.x to 3.x

When upgrading from LoopBack 2.x, you need to disable or remove remoting.context configuration in your server config.

{
  "remoting": {
    "context": false, // or remove completely
    // etc.
  },
  // etc.
}

Without this change, you will see the following error on the first HTTP request received:

Unhandled error for request GET /api/Users:
Error: remoting.context option was removed in version 3.0.
See https://docs.strongloop.com/display/APIC/Using%20current%20context for more
details.
    at restApiHandler (.../node_modules/loopback/server/middleware/rest.js:44:15)
    at Layer.handle [as handle_request] (.../node_modules/express/lib/router/layer.js:95:5)

Setting up "current context" in 3.x

To setup "current context" feature in your LoopBack 3.x application, you should use loopback-context module:

1. Add loopback-context to your dependencies

2. Configure the new context middleware in your server/middleware-config.json file

   {
     "initial": {
       "loopback-context#per-request": {}
     }
   }
   

3. Replace all usages of loopback.getCurrentContext with the following:

   // at the top of your file
   var LoopBackContext = require('loopback-context');
   
   // in your code
   var ctx = LoopBackContext.getCurrentContext();
   if (ctx) {
     // use the context
   }
   

See also loopback#2564 and the official documentation

Remove sugar for creating models

app.model(modelName, settings), a sugar for creating non-existing model, is now removed in favor of promoting use of:

• app.registry.createModel(modelName, properties, options) to create new model
• app.model(modelCtor, config) to update existing model and attach it to app

Please see related code change here.