Data: changedAttributes doesn't return changed relationships

[jamesarosen]

Currently, changedAttributes relies on comparing _data and _attributes. _attributes doesn't include any information about (belongs-to) relationships, so changing one won't show up in changedAttributes.

It's totally reasonable that changedAttributes should _not_ return relationship information because of its name. In that case, there should be a separate changedRelationships to match it.

[jamesarosen]

Related to #1367. Possibly should be part of #1308 or #2545

[arenoir]

IMO changing a belongs to association should show up in changedAttributes because the foreign_key would have changed.

[igorT]

It's specifically called changed attributes, there will be a specific one for relationship pretty soon, but it is very not trivial. Maybe we can get away with partial solutions for a while.

[arenoir]

@igorT given the following example.

//models/job.js
import Ember from 'ember';
export default DS.Model.extend({
  address: DS.belongsTo('address')
});

//routes/job.js
export default Ember.Route.extend( {
  model: function() {
    return this.store.find('job', params.id);
  },

  actions: {
    changeAddress: function(address) {
      var model = this.get('currentModel');

      model.set('address', address);
    },

    save: function() {
      var model = this.get('currentModel);

      if (model.get('isDirty')) {
        return model.save();
      }
    }
  }
}

Doesn't it make sense that calling the changeAddress action would update the addressId attribute thus marking the model dirty?

Currently the save action would not fire because changing the address doesn't mark the model dirty even though the foreign key changed.

Am I missing something? Is belongs to not relational with a foreign key attribute?

[arenoir]

@igorT, @jamesarosen, it keeps getting harder and harder to track if a belongs_to relationship has changed. I am not talking about testing for changes on the attributes of related models just testing if say a books.author has been changed.

In rails terms belongsTo is feeling more like hasOne.

Is there a current work around as the data hash no longer includes the foreign_key.

[leifdejong]

I don't know if this helps but I extended changedAttributes to also return changed relationships. I also included a snippet to commit without using the .save() method.

Model.reopen({

  /**
   * commit() saves changes locally without pushing to the server
   */
  commit() {
    this.get('_internalModel').send('willCommit');
    this.set('_internalModel._attributes', {});
    this.get('_internalModel').send('didCommit');
  },

  /**
   * changedAttributes() extends changedAttributes() to also return changed relationships
   */
  changedAttributes() {
    const attributes = this._super(...arguments);
    const relationships = {};

    // check relationships
    this.eachRelationship((name, meta) => {
      if (meta.kind === 'belongsTo') {
        if (this.get(`_data.${name}.id`) !== this.get(`${name}.id`)) {
          relationships[name] = [
            this.get(`_data.${name}.id`),
            this.get(`${name}.id`),
          ];
        }
      }
    });

    return Ember.merge(attributes, relationships);
  },
});

[BennyAlex]

@leifdejong thank you, this helped me alot

[BennyAlex]

@leifdejong why you check if meta.kind === 'belongsTo', what is with 'hasMany'?

[uhrohraggy]

@igorT Any reason this got closed? this is still a legitimate issue and something like changedRelationships is not available....

[atomkirk]

@leifdejong solution didn't work for me, so I modified it to get all up in those private apis bidness:

import DS from 'ember-data'

export default DS.Model.reopen({

  // this could break at the drop of a hat, so we'll want to test it thoroughly
  changedAttributes() {
    const attributes = this._super(...arguments)
    const relationships = {}

    // check relationships
    this.eachRelationship((name, meta) => {
      if (meta.kind === 'belongsTo') {

        let before = this.get(`_internalModel._relationships.initializedRelationships.${name}.canonicalState.id`)
        let now = this.get(`${name}.id`)

        if (before !== now) {
          relationships[name] = [before, now]
        }
      }
    })

    return Ember.merge(attributes, relationships)
  },

})

[Techn1x]

Can confirm @leifdejong solution is broken for me too (was previously working though).

Really wish I didn't have to resort to using private api's for this sort of stuff...

@atomkirk's solution above works in most cases, although I did have an issue where on calling it the first time on a model that has been retreived through findRecord, with no changes made, it would return something like;
{company: [undefined, "a9bd3ba7-9c34-428b-a9a0-59751a319940"]}
for my company belongsTo relation.

But then if I called model.changedRelationships() again, it would then correctly show
{}

So not sure what's up there. Stepping through the code it seems that the line that sets now modifies the result the next time you go to set before

This solution also exists (but I haven't tried it)
https://github.com/isleofcode/ember-changed-relationships/blob/master/addon/mixins/changed-relationships.js