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问题:

I've been trying out Angular JS for the past couple of days and one thing I can't figure out is how to work with relationships between models.

The project I'm working on has a Users model and an Accounts model. I have it set up on my database that each Account has a field called 'ownedBy' which is a foreign key reference to the id of the user that owns that account.

In Angular I have the following set up in a file called main.js

var myApp = angular.module('myApp', ['ngResource']);

var Users = myApp.factory('Users', function($resource) {
    var User = $resource('http://api.mydomain.ca/users/:id',
        {id:'@id'},
    {});
    return User;
});

var Accounts = myApp.factory('Accounts', function($resource) {
    var Accounts = $resource('http://api.mydomain.ca/accounts/:id',
        {id:'@id'},
    {});
    return Accounts;
});


function UsersCtrl($scope, Users) {
    $scope.users = Users.query();
}

function AccountsCtrl($scope, Accounts) {
    $scope.accounts = Accounts.query();
}

and the following template

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
  <title>Angular Test</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0">

  <link rel="stylesheet" href="/bootstrap/css/bootstrap.min.css?v=2.2.1">
</head>
<body>
<div ng-app="myApp">
    <div ng-controller="UsersCtrl">
        <table class="table table-striped">
            <thead>
                <tr>
                    <th>ID</th>
                    <th>First Name</th>
                    <th>Last Name</th>
                </tr>
            </thead>
            <tbody>
                <tr ng-repeat="user in users">
                    <td>{{user.id}}</td>
                    <td>{{user.firstName}}</td>
                    <td>{{user.lastName}}</td>
                </tr>
            </tbody>
        </table>
    </div>
    <div ng-controller="AccountsCtrl">
        <table class="table table-striped">
            <thead>
                <tr>
                    <th>ID</th>
                    <th>Owned By</th>
                </tr>
            </thead>
            <tbody>
                <tr ng-repeat="account in accounts">
                    <td>{{account.id}}</td>
                    <td>{{account.ownedBy}}</td>
                </tr>
            </tbody>
        </table>
    </div>
</div>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.0.4/angular.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.0.4/angular-resource.min.js"></script>
<script src="/bootstrap/js/bootstrap.min.js?v=2.2.1"></script>
<script src="js/main.js"></script>
</body>
</html>

and this is working. It pulls a JSON resource from my REST server and displays it in a table. What's the next step I need to take to end up with one table that shows users and their account numbers? (the equivalent of a database JOIN?) Is there a different way to do it for a one to many relationship? (ie... an account has many transactions)

Thanks for the help :)

回答1:

$resource doesn't contain any way to deal with relationships that aren't handled by the server, but it's pretty simply with $http:

module.factory( 'UserService', function ( $http, $q ) {
  return {
    get: function getUser( id ) {
      // We create our own promise to return
      var deferred = $q.defer();

      $http.get('/users/'+id).then( function ( user ) {
        $http.get('/accounts/'+user.id).then( function ( acct ) {

          // Add the account info however you want
          user.account = acct;

          // resolve the promise
          deferred.resolve( user );

        }, function getAcctError() { deferred.reject(); } );
      }, function getUserError() { deferred.reject(); } );

      return deferred.promise;
    }
  };
});

And then in your controller, you can just use it like any other promise:

UserService.get( $scope.userId ).then( function ( user ) {
  $scope.user = user;
});

And it's available for your template!

<div>
    User: "{{user.firstName}} {{user.lastName}}" with Acct ID "{{user.acct.id}}".
</div>

回答2:

I use js-data if I need relationships in the UI. The library handles relationships and data modelling pretty elegantly in general. I have found it easier to use even if you are just looking for a nice API interface. I prefer it to ngResource.

In your case you would have a model for User and model for Account

src/app/data/account.model.coffee

angular.module 'app.data' #this can be your module name
  .factory 'Account', (DS) ->
    DS.defineResource
      name: 'account'
      endpoint: 'accounts'
      relations:
        belongsTo:
          user:
            localKey: 'userId'
            localField: 'user'

src/app/data/user.model.coffee

angular.module 'app.data'
  .factory 'User', (DS) ->

    DS.defineResource
      name: 'user'
      endpoint: 'users'
      relations:
        belongsTo:
          account: #make sure this matches the 'name' property of the other model
            foreignKey: 'userId'
            localField: 'account'