How can I perform a where-in type query using ember-data?
Say I have a list of tags - how can I use the store to query the API to get all relevant records where they have one of the tags present?
Something like this:
return this.store.find('tags', {
name: {
"in": ['tag1', 'tag2', 'tag3']
}
})
There isn't built in support for something like that. And, I don't think its needed.
The result that you are after can be obtained in two steps.
return this.store.find('posts'); // I guess its a blog
and then in your controller you use a computed property
filteredPosts: function('model', function() {
var tags = ['tag1', 'tag2', 'tag3'];
return this.get('model').filter(function(post) {
if ( /* post has one of tags */ ) {
}
return false;
});
});
Update: What if there are tens of thousands of tags?!
Amother option is to send a list of tags as a single argument to the back end. You'll have to do a bit of data processing before sending a request and before querying.
return this.store.find('tags', {
tags: ['tag1', 'tag2', 'tag3'].join(', ')
})
In your API you'll know that the tags argument needs to be converted into an array before querying the DB.
So, this is better because you avoid the very expensive nested loop caused by the use of filter. (expensive !== bad, it has its benefits)
It is a concern to think that there will be tens of thousands of tags, if those are going to be available in your Ember app they'll have a big memory footprint and maybe something much more advanced is needed in terms of app design.
Related
I want to find a better way to update local component state after executing mutation. I'm using svelte-apollo but my question is about basic principles. I have watchQuery which get list of items and returns ObservableQuery in component.
query GetItems($sort: String, $search: String!) {
items(
sort: $sort
where: { name_contains: $search }
) {
id
name
item_picture{
pictures{
url
previewUrl
}
}
description
created_at
}
}
In component I call it:
<script>
$: query = GetItems({
variables: {
sort: 'created_at:DESC',
search
}
});
</script>
...
{#each $query.data?.items || [] as item, key (item.id)}
<div>
<Item
deleteItem={dropItem}
item={item}
setActiveItem={setActiveItem}
/>
</div>
{/each}
...
And I have addItem mutation.
mutation addItem($name: String!, $description: String) {
createItem(
input: { data: { name: $name, description: $description } }
) {
item {
name
description
}
}
}
I just simply want to update local state and add new item to an observable query result after addItem mutation, without using refetchQueries (because I don't want to get all list by network when I just added one item).
I seen this item in cache but my view is not updated.
P.S. If you have similar problems and some ways to solve it, be glad to see some cases from you.
I believe in this case, you could use the cache.modify function to modify the cache directly if you’re looking to skip the network request from refetchQueries. Would that work for your use case? https://www.apollographql.com/docs/react/data/mutations/#making-all-other-cache-updates
If you don’t mind the network request, I like using cache.evict to evict the data in the cache that I know changed personally. I prefer that to refetchQueries in most cases because it refetches all queries that used that piece of data, not just the queries I specify.
create a view that return only a subset of values from a document, each with its key and value within a json string. like if one given view returns a document as this following, Is it possible to get some fields information for a one request? thank you
{
"total_rows":10,
"offset":3,
"rows":[{
"id":"doc1",
"key":"abc123",
"value": {
"_id":"aaaa",
"_rev":"bbb",
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa#email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}],
"field10"::"0000",
"field11"::"55555",
"field12"::"0030".........
}
}
I just want to create a view that returns some fields only the following:
{
"field1":"abc",
"field2":"bcd",
"field3":"cde",
"field4":"123",
"field5":"789",
"field6":"aa#email.com",
"field7":"ttt",
"field8":"iii",
"field9":[{
"field91":"tyui",
"field92":"55555"
}]
}
A map function that emits a new document with selected fields only. As an example, let's map field1 (a string) and field9 (an array) only:
function map(doc) {
emit(doc._id, {
field1: doc.field1,
field9: doc.field9
});
}
In the above example, each document will be fired with a key being the original doc ID and the value being the mapped fields you require.
This is useful if you are planning to add a reduce function later.
Depending on your use case, you may just want to emit the mapped objects:
function map(doc) {
emit({
field1: doc.field1,
field9: doc.field9
});
}
Please see http://guide.couchdb.org/draft/views.html
The documentation on building data views is pretty good, you can discover a lot by experimenting..
In Loopback it is easy to include relational objects when querying for data. For example, one can include all the comments that belong to a blog post in a single call using the include filter.
But in my case I want to get data that doesn't have a relation.
I have a User Detail page. On that page a user can choose a username and there's also a dropdown list where a user can choose from what country he is.
So from the client side I do something like:
Country.find().$promise.then(function(countryData) {
$scope.countries = countryData;
});
Player.find().$promise.then(function(playerData) {
$scope.player = playerData;
}
But what if I get more lists that I want to fill? Like, city, state, colors etc.
Then I'd have to make a lot of separate calls.
Is there a way to include all this data in one call, eventhough they have no relation? Something like this:
Player.find({ filter: { include: ["countries", "colors"] } }).$promise.then(function(data) {
// some stuff
}
You may want to try using the Where filter as documented here
An example of this for querying two specific things would be:
Post.find({where: {and: [{title: 'My Post'}, {content: 'Hello'}]}},
function (err, posts) {
...
});
You could create a remote method on one of your models that makes the calls internally and packages them back up for you.
Use some promise library if not using ES6 to wait for all and then return
Model.getAll = function(next) {
var promises = [];
promises.push(Model.app.models.Country.find());
promises.push(Model.app.models.Player.find());
promises.push(Model.app.models.Color.find());
Promise.all(promises)
.then(function(results) {
next(results);
});
}
/**
Register your remote method here
*/
You could create a remote method on one of your models that makes the calls internally and packages them back up for you.
Use some promise library if not using ES6 to wait for all and then return
Model.getAll = function(next) {
var promises = [];
promises.push(Model.app.models.Country.find());
promises.push(Model.app.models.Player.find());
promises.push(Model.app.models.Color.find());
Promise.all(promises)
.then(function(results) {
next(results);
});
}
/**
Register your remote method here
*/
I have problem and try with this solution but i get error "Failed with multiple errors, see details for more information.". It seems like there is bug on Loopback while using promise.all
I want to be able to retrieve a certain conversation when its id is entered in the URL. If the conversation does not exist, I want to display an alert message with a record not found.
here is my model hook :
model: function(params){
return this.store.filter('conversation', { status : params.status}, function(rec){
if(params.status == 'all'){
return ((rec.get('status') === 'opened' || rec.get('status') === 'closed'));
}
else{
return (rec.get('status') === params.status); <--- Problem is here
}
});
}
For example, if I want to access a certain conversation directly, I could do :
dev.rails.local:3000/conversations/email.l#email.com#/convid
The problem is when I enter a conversation id which doesn't exist (like asdfasdf), ember makes call to an inexisting backend route.
It makes a call to GET conversation/asdfasdf. I'm about sure that it is only due to the record not existing. I have nested resources in my router so I'm also about sure that it tries to retrieve the conversation with a non existing id.
Basically, I want to verify the existence of the conversation before returning something from my hook. Keep in mind that my model hook is pretty much set and won't change, except for adding a validation on the existence of the conversation with the id in the url. The reason behind this is that the project is almost complete and everything is based on this hook.
Here is my router (some people are going to tell me you can't use nested resources, but I'm doing it and it is gonna stay like that so I have to work with it because I'm working on a project and I have to integrate ember in this section only and I have to use this setup) :
App.Router.map(function(){
// Routing list to raw namespace path
this.resource('conversations', { path : '/' }, function() {
this.resource('conversation', { path : '/:conversation_id'});
});
});
This also happens when I dont specify any id and I use the hashtag in my url like this :
dev.rails.local:3000/conversations/email.l#email.com#/ would make a call to conversation/
I know it is because of my nested resource. How can I do it?
By passing a query to filter (your { status : params.status}) you are asking Ember Data to do a server query. Try removing it.
From the docs at http://emberjs.com/api/data/classes/DS.Store.html#method_filter:
Optionally you can pass a query, which is the equivalent of calling find with that same query, to fetch additional records from the server. The results returned by the server could then appear in the filter if they match the filter function.
So, remove the query:
model: function(params){
return this.store.filter('conversation', function(rec) {
if (params.status == 'all') {
return rec.get('status') === 'opened' || rec.get('status') === 'closed';
} else {
return rec.get('status') === params.status;
}
});
}
Ok so here is what I did. I removed my nested resource because I realised I wasn't using it for any good reason other than redirecting my url. I decided to manually redirect my url using javascript window.location.
This removed the unwanted call (which was caused by the nested resource).
Thanks to torazaburo, you opened my eyes on many things.
I have a DS.Store which uses the DS.RESTAdapter and a ChatMessage object defined as such:
App.ChatMessage = DS.Model.extend({
contents: DS.attr('string'),
roomId: DS.attr('string')
});
Note that a chat message exists in a room (not shown for simplicity), so in my chat messages controller (which extends Ember.ArrayController) I only want to load messages for the room the user is currently in:
loadMessages: function(){
var room_id = App.getPath("current_room.id");
this.set("content", App.store.find(App.ChatMessage, {room_id: room_id});
}
This sets the content to a DS.AdapterPopulatedModelArray and my view happily displays all the returned chat messages in an {{#each}} block.
Now it comes to adding a new message, I have the following in the same controller:
postMessage: function(contents) {
var room_id = App.getPath("current_room.id");
App.store.createRecord(App.ChatMessage, {
contents: contents,
room_id: room_id
});
App.store.commit();
}
This initiates an ajax request to save the message on the server, all good so far, but it doesn't update the view. This pretty much makes sense as it's a filtered result and if I remove the room_id filter on App.store.find then it updates as expected.
Trying this.pushObject(message) with the message record returned from App.store.createRecord raises an error.
How do I manually add the item to the results? There doesn't seem to be a way as far as I can tell as both DS.AdapterPopulatedModelArray and DS.FilteredModelArray are immutable.
so couple of thoughts:
(reference: https://github.com/emberjs/data/issues/190)
how to listen for new records in the datastore
a normal Model.find()/findQuery() will return you an AdapterPopulatedModelArray, but that array will stand on its own... it wont know that anything new has been loaded into the database
a Model.find() with no params (or store.findAll()) will return you ALL records a FilteredModelArray, and ember-data will "register" it into a list, and any new records loaded into the database will be added to this array.
calling Model.filter(func) will give you back a FilteredModelArray, which is also registered with the store... and any new records in the store will cause ember-data to "updateModelArrays", meaning it will call your filter function with the new record, and if you return true, then it will stick it into your existing array.
SO WHAT I ENDED UP DOING: was immediately after creating the store, I call store.findAll(), which gives me back an array of all models for a type... and I attach that to the store... then anywhere else in the code, I can addArrayObservers to those lists.. something like:
App.MyModel = DS.Model.extend()
App.store = DS.Store.create()
App.store.allMyModels = App.store.findAll(App.MyModel)
//some other place in the app... a list controller perhaps
App.store.allMyModels.addArrayObserver({
arrayWillChange: function(arr, start, removeCount, addCount) {}
arrayDidChange: function(arr, start, removeCount, addCount) {}
})
how to push a model into one of those "immutable" arrays:
First to note: all Ember-Data Model instances (records) have a clientId property... which is a unique integer that identifies the model in the datastore cache whether or not it has a real server-id yet (example: right after doing a Model.createRecord).
so the AdapterPopulatedModelArray itself has a "content" property... which is an array of these clientId's... and when you iterate over the AdapterPopulatedModelArray, the iterator loops over these clientId's and hands you back the full model instances (records) that map to each clientId.
SO WHAT I HAVE DONE
(this doesn't mean it's "right"!) is to watch those findAll arrays, and push new clientId's into the content property of the AdapterPopulatedModelArray... SOMETHING LIKE:
arrayDidChange:function(arr, start, removeCount, addCount){
if (addCount == 0) {return;} //only care about adds right now... not removes...
arr.slice(start, start+addCount).forEach(function(item) {
//push clientId of this item into AdapterPopulatedModelArray content list
self.getPath('list.content').pushObject(item.get('clientId'));
});
}
what I can say is: "its working for me" :) will it break on the next ember-data update? totally possible
For those still struggling with this, you can get yourself a dynamic DS.FilteredArray instead of a static DS.AdapterPopulatedRecordArray by using the store.filter method. It takes 3 parameters: type, query and finally a filter callback.
loadMessages: function() {
var self = this,
room_id = App.getPath('current_room.id');
this.store.filter(App.ChatMessage, {room_id: room_id}, function (msg) {
return msg.get('roomId') === room_id;
})
// set content only after promise has resolved
.then(function (messages) {
self.set('content', messages);
});
}
You could also do this in the model hook without the extra clutter, because the model hook will accept a promise directly:
model: function() {
var self = this,
room_id = App.getPath("current_room.id");
return this.store.filter(App.ChatMessage, {room_id: room_id}, function (msg) {
return msg.get('roomId') === room_id;
});
}
My reading of the source (DS.Store.find) shows that what you'd actually be receiving in this instance is an AdapterPopulatedModelArray. A FilteredModelArray would auto-update as you create records. There are passing tests for this behaviour.
As of ember.data 1.13 store.filter was marked for removal, see the following ember blog post.
The feature was made available as a mixin. The GitHub page contains the following note
We recommend that you refactor away from using this addon. Below is a short guide for the three filter use scenarios and how to best refactor each.
Why? Simply put, it's far more performant (and not a memory leak) for you to manage filtering yourself via a specialized computed property tailored specifically for your needs