A BelongsToReference is a low level API that allows users and addon author to perform meta-operations on a belongs-to relationship.

The id of the record that this reference refers to. Together, the type() and id() methods form a composite key for the identity map. This can be used to access the id of an async relationship without triggering a fetch that would normally happen if you attempted to use record.get('relationship.id').

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         data: { type: 'user', id: 1 }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 // get the identifier of the reference
 if (userRef.remoteType() === "id") {
   var id = userRef.id();
 }

The link Ember Data will use to fetch or reload this belongs-to relationship.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         links: {
           related: '/articles/1/author'
         }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 // get the identifier of the reference
 if (userRef.remoteType() === "link") {
   var link = userRef.link();
 }

Loads a record in a belongs to relationship if it is not already loaded. If the relationship is already loaded this method does not trigger a new load.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         data: { type: 'user', id: 1 }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 userRef.value(); // null

 userRef.load().then(function(user) {
   userRef.value() === user
 });

The meta data for the belongs-to relationship.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         links: {
           related: {
             href: '/articles/1/author',
             meta: {
               lastUpdated: 1458014400000
             }
           }
         }
       }
     }
   }
 });

 var userRef = blog.belongsTo('user');

 userRef.meta() // { lastUpdated: 1458014400000 }

push can be used to update the data in the relationship and Ember Data will treat the new data as the conanical value of this relationship on the backend.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         data: { type: 'user', id: 1 }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 // provide data for reference
 userRef.push({
   data: {
     type: 'user',
     id: 1,
     attributes: {
       username: "@user"
     }
   }
 }).then(function(user) {
   userRef.value() === user;
 });

Triggers a reload of the value in this relationship. If the remoteType is "link" Ember Data will use the relationship link to reload the relationship. Otherwise it will reload the record by its id.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         data: { type: 'user', id: 1 }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 userRef.reload().then(function(user) {
   userRef.value() === user
 });

This returns a string that represents how the reference will be looked up when it is loaded. If the relationship has a link it will use the "link" otherwise it defaults to "id".

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   type: 'blog',
   id: 1,
   relationships: {
     user: {
       data: { type: 'user', id: 1 }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 // get the identifier of the reference
 if (userRef.remoteType() === "id") {
   var id = userRef.id();
 } else if (userRef.remoteType() === "link") {
   var link = userRef.link();
 }

value() synchronously returns the current value of the belongs-to relationship. Unlike record.get('relationshipName'), calling value() on a reference does not trigger a fetch if the async relationship is not yet loaded. If the relationship is not loaded it will always return null.

Example

 // models/blog.js
 export default DS.Model.extend({
   user: DS.belongsTo({ async: true })
 });

 var blog = store.push({
   data: {
     type: 'blog',
     id: 1,
     relationships: {
       user: {
         data: { type: 'user', id: 1 }
       }
     }
   }
 });
 var userRef = blog.belongsTo('user');

 userRef.value(); // null

 // provide data for reference
 userRef.push({
   data: {
     type: 'user',
     id: 1,
     attributes: {
       username: "@user"
     }
   }
 }).then(function(user) {
   userRef.value(); // user
 });