I am having trouble with a specific case using Ember-Data.
Typically Ember expects a model class, the route, the ajax request, and the returned JSON, to all follow a similar pattern.
The RESTAdapter tries to automatically build a URL to send to the server, which is ok for some situations, but I need full control over some of my request URLs particularly when it comes to appending additional parameters, or matching an API to a route that has a completely different URL structure.
Ember sadly, has no guides for this, though I did find something about the buildURL method
I am not comfortable enough rooting through the source code to find out what happens under the hood though I do not want to break ember data just to fix a few use cases.
I have set my RESTAdapter's namespace to api/rest
The model and resource I want to populate is view-debtors
The specific service I want to reach is at debtor/list
I also need to pass extra parameters for pagination ?page_size=10&page_number=1, for example.
I am completely lost how to do this. I cannot change the API structure... there are too many services depending on them.
Some Small Progress
I went ahead and used my current knowledge to get a little closer to the solution.
I created a model and called it "list"
I extended RESTAdapter for "list" to change the namespace to "api/rest/debtor"
I changed the model hook for "view-debtors" route to store.find('list')
The result now is that the AJAX call is almost correct... I just need to add those extra parameters to the server queries.
This is where I stand now... can I add those server queries via the model hook? or better yet can I also control server queries via ember actions to get new AJAX requests?
Stepping back a bit. Is my method so far a good practice? Because I am using a route's model hook, to set the model to list, will this only work if the routes URL is typed in directly?
So many questions :p
You can find by query which will append a query string onto the end of your request using the object provided.
// this would produce /api/rest/debtor/lists?page_size=1&page_number=10
this.store.find('list', {page_size:1, page_number:10});
Personally I think it's a bit hacky to go fudging the model names and namespace to make it supposedly fit your backend's url structure. It really depends on what you're attempting to do. If you want all the full features of CRUD using Ember-Data for this particular list of data, you're going to be hacking the end-point left and right. Whether or not Ember Data really helps you is questionable. If you are just reading data, I'd totally just fetch the data using jquery and sideload it into Ember Data.
var store = this.store;
$.getJSON('/api/rest/debtor/lists?page_size=1&page_number=10').then(function(json){
//fix payload up if necessary http://emberjs.com/api/data/classes/DS.Store.html#method_pushPayload
store.pushPayload('type', json);
}).then(function(){
return store.all('type'); // or store.filter('type') if you want to filter what is returned to the model hook
});
pushPayload docs
Related
I am new to ember and am trying to migrate an existing application, and would like to know what the recommendation is for modeling a single object that will be reused in multiple components on every page. ie: As part of the initial load, I would like to perform a GET request against a URL like 'https://example.com/currentUser' and get an object back like:
{
name: "Users Name"
email: "user#email.com",
profileImg: "http://example.com/pictureOfUser.png"
... snip ...
}
This object will then be used in components for menus, toolbars, and a form for updating it via a post to the same URL.
What is the best way to model this workflow in ember? Given that this is an incidental object and not the focus of most routes, it does not seem to make sense to specify it as the model of them. Also, does ember data handle cases where a model is a singleton and does not have an ID, or would I need to use something like Ember.$.ajax ?
What do you mean by "where a model is a singleton"?
If you use the ember-data default adapter, then yes, a model needs to have an ID, it's part of the JSONAPI spec. If you already have a backend with different conventions, take a look at extending or swapping out the default adapter.
A service is a singleton, and there is nothing preventing you from making an AJAX call there. You would be losing out on all the nice things that come along with ember-data, but, you can do it.
This topic har been discussed on stackoverflow before, but not with latest version of ember data, I think. At least none of the suggestions I have found have worked for me.
I use the latest version of Ember and Ember data (versjon 2.13.0). I use the JsonApiAdapter.
Scenario
After I load a record from the server I want to do a few changes to some of its properties. These changes shall not make the record dirty, and the changed attributes shall not show up in the record.changedAttributes(). Any changes the user may do after that shall make the record dirty.
Searching for a solution
I have tried to manually change the isDirty flag, but it didn't do it. I have also tried to find the place in the ember data code that sets the state after a record has been loaded (because essentially I am trying to do the same thing) but I haven't found where it is.
I have also tried record.send('pushedData'), but I didn't change anything of the state of the record.
Any help appreciated.
I know 3 methods which allow to modify server's response without dirtying records:
You can override adapter's handleResponse method and make modifications right in payload.
You can override serializer's normalize method.
You can load records from server with Ember.$.ajax method, modify response and then pass it to store's pushPayload method.
First two methods are good if you need to modify record after every load from server (no matter from what route/controller you do it). Both adapter and serializer can be model-specific. If you need to do it in only one place (controller or route), or if you need an access to route's/controller's variables - 3rd method is good.
I'm not aware about any way to mark record as dirty/not dirty. If you modify a record after it was stored, it becomes dirty.
From EmberJS documentation i get the following two ways to retrieve all records of a given type, one that makes a request and one that doesn't.
var posts = this.store.findAll('post'); // => GET /posts
var posts = this.store.peekAll('post'); // => no network request
It seems to me that i always need to do first a findAll but isn't clear for my understanding when should i do a peekAll.
For example, the user enters my blog and then i get all the posts using findAll, then at some point in the same flow i need all those post, so i should use a peekAll to save bandwidth. So how should i know that i have requested all posts previously ? Should i save some global state to handle that ?
I would assume that the first time the client request a peekAll if there isn't any record it will automatically do a findAll or maybe i should that manually but it probably introduce some boilerplate.
How do you use in practice findAll and peekAll or they equivalents for single record ? Any recommendation ?
.findAll is cached:
First time store.find is called, fetch new data
Next time return cached data
Fetch new data in the background and update
This is the behavior of the new findRecord and findAll methods.
As you can read in Ember Data v1.13 blog post.
So, taking your example:
var posts = this.store.findAll('post'); // => GET /posts
// /\ or load from cache and update data in background /\
var posts = this.store.peekAll('post'); // => no network request
And:
It seems to me that i always need to do first a findAll but isn't
clear for my understanding when should i do a peekAll.
Yes, you need to do first .findAll, but you are encouraged to use .findAll in all places, as it is cached and suited for multiple requests for data (from many places across application without wasting bandwidth).
For example, the user enters my blog and then i get all the posts
using findAll, then at some point in the same flow i need all those
post, so i should use a peekAll to save bandwidth. So how should i
know that i have requested all posts previously ? Should i save some
global state to handle that ? I would assume that the first time the
client request a peekAll if there isn't any record it will
automatically do a findAll or maybe i should that manually but it
probably introduce some boilerplate.
I think user needs to have always up to date data in your application. What if you add blog post while he is browsing page? If you would use .peekAll() then user would need to refresh page to get latest data.
If you would like to save bandwidth then I would recommend you to implement maybe some kind of additional logic in Ember Adapter, but you have to find way to balance user requests with need to always serve latest data. You can do this by overriding Adapter's methods:
shouldReloadAll: function(store, snapshotRecordArray)
shouldBackgroundReloadAll: function(store, snapshotRecordArray)
See more info about these methods in Ember API docs.
How do you use in practice findAll and peekAll or they equivalents for
single record ? Any recommendation ?
If you are completely sure that you always have up to date data after first request then use .peekAll. There is data can be always up to date, because, for example it almost never changes in your database. It depends however what are your needs and how did you design your data models. It's hard to find good example, but maybe imagine if you would have some models which contain only constants. Like PI value etc. Maybe you have imported it from somewhere and it is complete, closed set of something that will never change. Then, after first .findAll, (for example if it's core function to your application it could be defined in Application route beforeModel hook) you would be sure that no more requests are needed and you have all data.
You could also use .peekAll if your application would have something like Offline Mode and can rely only on data you already have.
How do you paginate the request for related data? For example, if my Person has a thousand Task models attached to it if I do the following, in RESTful thinking, I would get all of them.
var tasks = person.get('tasks');
That would be way too much data. How do I force some query parameter onto the request that works behind the scenes? Ideally to an endpoint with something like this attached to the end of it.
?&offset=3&limit=3
Here is a fiddle to illustrate what I'm trying to accomplish in the IndexController. I have no idea what the "ember way" is to do paginated requests using ember-data.
It didn't exist when this question was first asked, but there is now an addon called ember-data-has-many-query that seems capable of this, at least for RESTAdapter and JSONAPIAdapter. It appears to have some quirks due to ember-data not yet supporting pagination as a first-class concept. If this makes you uneasy, there is always store.query, but this does require your API to support (in your example) a person_id filter parameter on the /tasks endpoint.
Related:
ember-data issue #3700: Support query params when fetching hasMany relationship
json-api issue #509: Pagination of to-many relationships is underspecified
(it doesn't look like this question involved JSON API, but the discussion is relevant)
As today there is still no default way to handle pagination in ember.
First we should probably look at the more simple thing, pagination of a findAll request.
This can be done with something like .query({page:3}), but leads to some Problems:
This is a good solution for classic pagination, but for a infinite-scroll you still need to manually merge the results.
The results are not cached, so moving forward and backward on an paginated list results in a lot of querys. Sometimes this is necessary if the list is editable, but often its not.
For the second problem I build a little addon called ember-query-cache that hooks into the store and allows you to cache the query results. A very short demo is available here.
Now if we talk about a relationship I would honestly recommend to use top level .query until you have better support from ember-data itself:
store.query('task', { person: get(person, 'id'), page: 3 }
There is nothing bad about it. You get your result and have the relationship in the other direction. It works without any hacking into ember-data as long you don't need caching, and if you need caching it requires the very few hacking I've done in my addon.
We still hope for ember-data to become fully JSONAPI complete, and that would require pagination. I think form an API perspective the best thing would be to have the ability to ask for the next and previous page on the ManyArray returned by the relationship. It would along with the JSONAPI where a next and previous link is provided. But to acomplish that now you would have to hack deep into ember-data without getting a big improvement over the top level .query, which I used successfully in many projects.
From the Ember.js guides on using models, you can also submit a query along with the find() call.
this.store.find('person', { name: "Peter" }).then(function(people) {
console.log("Found " + people.get('length') + " people named Peter.");
});
From the guide:
The hash of search options that you pass to find() is opaque to Ember
Data. By default, these options will be sent to your server as the
body of an HTTP GET request.
Using this feature requires that your server knows how to interpret
query responses.
I can work with Ember.js(rc0) and Rails, and have a simple app working as I'd expect, but want to focus on a specific story:
As a user, I want to type in "filter" text in a form, then have my ArrayController only show me those items that match the filter. For example, think of a Contacts app that shows people with the name like "Ya%"...
Caveat: Say the database holds thousands of Contact records. I don't want to filter those contacts on the client, it makes more sense to do that on the server.
Question:
How do I do this in ember.js/ember-data? On the server, I can easily allow for a search parameter in my index URL to filter data so it's a manageable list, or even limit the response to say, 20 items.
I can also use a view to have access to my filter text in my controller, but where do I go next? How can I pass that filter onto the server?
Update:
I was able to use "find" on the model object, and ember (ember data) went to the server to grab new data - as the client side only had a subset of all the Contact records to begin with. Instead of filtering on what on the client, it automatically deferred to the the server... which is nice.
App.ContactIndexController = Ember.ArrayController.extend
search_term: null
submit: (view) ->
this.set('content', App.Contact.find({search: "#{view.search_term}"}))
This is a good use case for findQuery. For example:
store.findQuery(App.Contact, {q: queryString})
This will in turn call findQuery on the appropriate adapter, and if successful, load the returned records into the store and return a DS.AdapterPopulatedRecordArray.
Note that you can completely customize the query object to include params that match your server's endpoints.
Update: As Michael pointed out in the comments, the above is equivalent to:
App.Contact.find({q: queryString})
... which is certainly a cleaner solution, especially without direct access to the store.