Is there a way to exclude certain property from my model when I sync?
For example, I keep in my model information about some view state. Let's say I have a picker module and this module just toggle a selected attributes on my model. Later, when I call .save() on my collection, I'd want to ignore the value of selected and exclude it from the sync to the server.
Is there a clean way of doing so?
(Let me know if you'd like more details)
This seems like the best solution (based on #nikoshr referenced question)
Backbone.Model.extend({
// Overwrite save function
save: function(attrs, options) {
options || (options = {});
attrs || (attrs = _.clone(this.attributes));
// Filter the data to send to the server
delete attrs.selected;
delete attrs.dontSync;
options.data = JSON.stringify(attrs);
// Proxy the call to the original save function
return Backbone.Model.prototype.save.call(this, attrs, options);
}
});
So we overwrite save function on the model instance, but we just filter out the data we don't need, and then we proxy that to the parent prototype function.
In Underscore 1.3.3 they added pick and in 1.4.0 they added omit which can be used very simply to override your model's toJSON function to whitelist attributes with _.pick or blacklist attributes with _.omit.
And since toJSON is used by the sync command for passing the data to the server I think this is a good solution as long as you do not want these fields wherever else you use toJSON.
Backbone.Model.extend({
blacklist: ['selected',],
toJSON: function(options) {
return _.omit(this.attributes, this.blacklist);
},
});
my solution combine all the above. just use white list instead of black one .. this is good rule in general
define
attrWhiteList:['id','biography','status'],
and then overwrite the save
save: function(attrs, options) {
options || (options = {});
//here is whitelist or all
if (this.attrWhiteList != null )
// Filter the data to send to the server
whitelisted = _.pick(this.attributes, this.attrWhiteList);
else
whitelisted =this.attributes;
/* it seems that if you override save you lose some headers and the ajax call changes*/
// get data
options.data = JSON.stringify(whitelisted);
if ((this.get('id') == 0) || (this.get('id') == null))
options.type = "POST"
else
options.type = "PUT";
options.contentType = "application/json";
// options.headers = {
// 'Accept': 'application/json',
// 'Content-Type': 'application/json'
// },
// Proxy the call to the original save function
return Backbone.Model.prototype.save.call(this, attrs, options);
},
In fact there is a much simpler way of achieving this without messing with backbone save or sync function since you would no be expecting this behaviour to be permanent
if you look at backbone.js line 1145 you will see that
// Ensure that we have the appropriate request data.
if (options.data == null && model && (method === 'create' || method === 'update' || method === 'patch')) {
params.contentType = 'application/json';
params.data = JSON.stringify(options.attrs || model.toJSON(options));
}
Which means that you may override the data part of the xhr by putting data in your options
Since backbone save requires model.save([attributes], [options])
But remember that attributes like id might be essential to proper saving
Example
model.save( {}, { data: JSON.stringify(data) } ) ;
So you should be doing something like this
var data = { id : model.id , otherAttributes : 'value' } ;
model.save( {}, { data : JSON.stringify(data) } );
This do the trick quite well for me and could be used with any backbone with xhr such as fetch, save, delete, ...
Based on several of the answers, this accounts for cases of null objects and a conditional in Backbone that doesn't sent the contentType if options.data is already set:
EDITABLE_ATTRIBUTES = ["name", "birthdate", "favoriteFood"];
...
save: function(attrs, options) {
// `options` is an optional argument but is always needed here
options || (options = {});
var allAttrs = _.extend({}, this.attributes, attrs);
var allowedAttrs = _.pick(allAttrs, EDITABLE_ATTRIBUTES);
// If `options.data` is set, Backbone does not attempt to infer the content
// type and leaves it null. Set it explicitly as `application/json`.
options.contentType = "application/json";
options.data = JSON.stringify(allowedAttrs);
return Backbone.Model.prototype.save.call(
this, allowedAttrs, options);
},
I found some problems with the accepted solution, as options.data modifies the way Backbone makes the calls. Better using options.attrs as this:
Backbone.Model.extend({
save: function (attrs, options) {
options = options || {};
attrs = _.extend({}, _.clone(this.attributes), attrs);
// Filter the data to send to the server
delete attrs.selected;
options.attrs = attrs;
// Proxy the call to the original save function
return Backbone.Model.prototype.save.call(this, attrs, options);
}
});
Since save uses toJSON we override it:
toJSON: function(options) {
var attr = _.clone(this.attributes);
delete attr.selected;
return attr;
},
But it may not work if you're using toJSON and need selected in views for example. Otherwise you probably need to override save method.
Set options.attrs will allow you customise api param:
var model = new Backbone.Model();
model.save(null, {
wait: true,
success: function() {
},
attrs: _.omit(model.attributes, 'selected')
});
If it is a one-off occasion, you could use mode.unset('selected', { silent:true }) (silent is set only to avoid firing the change event), to remove the attribute... This has the not so nice counter-effect of having to re-set it after saving though.
This said, I totally endorse one of the solutions above. Moreover if this is something you need on a more regular basis.
To set only desired values, use HTTP PATCH insead of HTTP POST. On the backbone side, just add a patch attribute to the save method:
entity.save(data,{patch:true})
Using save with this attribute, only fields passed as data are sent to the server.
Having this same issue, I decided to create a small module that can help : https://github.com/lupugabriel1/backbone-model-save
This is how you can use it in your models:
var myModel = new Backbone.ModelSave.extend({
notSync: ['name', 'age']
});
Related
I'm looking for a way to intercept the value returned from a server when I fetch a backbone model (a collection, strictly speaking) from the server, then modify it before continuing. I would think that I could do something like this
SessionController.prototype._initPages = function() {
return App.pages.fetch({
reset: true,
success: function(model, response, options) {
//modify the contents of response
}
};
And my modifications would be reflected in the model that's used to initialize the view.
However I was looking at the backbone source and I think I may have misunderstood something.
fetch: function(options) {
options = options ? _.clone(options) : {};
if (options.parse === void 0) options.parse = true;
var success = options.success;
var collection = this;
options.success = function(resp) {
var method = options.reset ? 'reset' : 'set';
collection[method](resp, options); //this line updates the model
if (success) success(collection, resp, options); // my success callback
collection.trigger('sync', collection, resp, options);
};
wrapError(this, options);
return this.sync('read', this, options);
}
For my needs, it seems the two commented lines need to be switched, though I assume I'm just misunderstanding how to use this feature.
How can I modify the server response before it becomes my model?
I think you could just override the parse function to modify your data as needed
http://backbonejs.org/#Model-parse
So I have a Resource defined as follows:
angular.module('questionService', ['ngResource'])
.factory('QuestionService', function($http, $resource) {
var QuestionService = $resource('/api/questions/:key', {}, {
query: {
method:'GET',
isArray:true,
},
save: {
method: 'POST',
}
});
return QuestionService
});
And later on I take some form input and do the following
var newQ = {
txt: $scope.addTxt
};
QuestionService.save(newQ)
The server responds to the POST request both by reissuing the JSON for the object and setting the location header with the new unique ID. The problem is that Angular is not saving that returned JSON or the location header into the object and it is not getting set with the ID from the server for future operations. I've tried a number of things such as:
transformResponse: function(data, headersGetter) {
locationHeader = headersGetter().location;
key = locationHeader.split('/').slice(-1)[0];
data.key = key;
return data;
}
However the returned data item doesn't seem to be getting used. Am I missing something? This seems like a pretty common use case for interacting with a REST api.
Thanks!
You need to have a success handler to assign the new id to newQ manually:
QuestionService.save(newQ, function(data) {
newQ.id = data.id;
});
But there is a better to achieve the same. Because your QuestionService is a resource class object, you can instantiate your newQ like this:
var newQ = new QuestionService({text: $scope.addTxt});
Then, call $save() of newQ:
newQ.$save();
Now newQ should have the new id returned by the server.
I have Asp.Net server with WebApi2 running, i use Ok(number) to return content, and it return for example '6' as result. once it return, the angular show an object containing promise and state, and prototypes and a deep repeated hierarchy, but no value, no '6'.
So i went to see where the data goes, for seeing where the data is i define a transform, and i see awo the data, but it's not a json...
later i change it to following, and now i have a obj in my success function, which has sub property called 'returnValue' (as i defined), and this object hold my value.
transformResponse: function(data, header){
var obj={};
obj.returnValue=angular.fromJson(data);
return obj;
},
//A backbone model
var RequestModel = Backbone.Model.extend({});
//A backbone model
var ResponseModel = Backbone.Model.extend({});
RequestModel.save({
success: function (ResponseModel ) {
alert(ResponseModel .toJSON());
}
})
Can i have a separate Model for Request and Response, as both Request and Response does not match. Its a total RPC call and not a CRUD operation.
I've thought about this same problem before, and I feel there isn't a great way to achieve this in Backbone. The best I've come up with is to implement a fromResponse and toRequest method on the model, and override model.parse and model.sync to map the model object to them. Something like:
var Model = Backbone.Model.extend({
fromResponse: function(responseAttrs) {
var modelAttrs = {}; //map response attributes to modelAttrs
return modelAttrs;
},
toRequest: function() {
//map model attributes to response attributes here
var modelAttrs = this.toJSON();
var responseAttrs = {}; //map models attributes to requestAttrs
return responseAttrs;
},
parse: function(response) {
return this.fromResponse(response);
},
sync: function(method, model, options) {
options = options || {};
options.data = this.toRequest();
Backbone.sync(method, model, options);
}
});
If the parse and sync are overridden in some kind of a base class, then you only need to implement the fromResponse and toRequest mappers for each model.
Another option would be to override Backbone.sync altogether, and map each Model type to some kind of ModelRequestMapper and ModelResponseMapper object to (de-)serialize each model. I feel that would be more complicated, but might scale better, if you have lots of models.
/Code sample not tested
Is there any way to override Backbone.sync partially, say, only create and update, and leave read and delete to use native Backbone.sync?
Simple as that:
// retain original sync with new name
Backbone.ajaxSync = Backbone.sync;
Backbone.customSync = function(method, model, option) {
// Fallback for old sync method
if (method == 'read' || method == 'delete') return Backbone.ajaxSync(method, model, option);
// your custom code for other methods
console.log('Custom sync for ' + method);
}
Backbone.sync = Backbone.customSync;
For mapping my backbone models to what I get from the server I am using a technique described on the GroupOn Dev blog: https://engineering.groupon.com/2012/javascript/extending-backbone-js-to-map-rough-api-responses-into-beautiful-client-side-models/
However, this only maps incoming data to the model.
I would like this to go both ways, so that when I save a model, it prepares the models attributes to match the servers model.
What would be the best solution to prepare the output of the model?
I've run into this exact same issue where my server response is completely different from what I am able to post. I discovered within the mechanics of the Backbone.sync object a way to that I could post to my server a custom JSON object in the following statement in Backbone.sync:
if (!options.data && model && (method == 'create' || method == 'update')) {
params.contentType = 'application/json';
params.data = JSON.stringify(model.toJSON());
}
sync evaluates if options.data does not exist then sets the params.data to the stringified model. The options.data check keyed me off. If that exists, sync will use that instead of the model. So given this, I overrode my model.save so could pass in an attributes hash that my server expects.
Here's how I overrode it:
save : function(key, value, options) {
var attributes = {}, opts = {};
//Need to use the same conditional that Backbone is using
//in its default save so that attributes and options
//are properly passed on to the prototype
if (_.isObject(key) || key == null) {
attributes = key;
opts = value;
} else {
attributes = {};
attributes[key] = value;
opts = options;
}
//In order to set .data to be used by Backbone.sync
//both opts and attributes must be defined
if (opts && attributes) {
opts.data = JSON.stringify(attributes);
opts.contentType = "application/json";
}
//Finally, make a call to the default save now that we've
//got all the details worked out.
return Backbone.Model.prototype.save.call(this, attributes, opts);
}
So how do you use this in your case? Essentially what you'll do is create a method that reverses the mapping and returns the resulting JSON. Then you can invoke save from your view or controller as follows:
getReversedMapping : function() {
ver reversedMap = {};
...
return reversedMap;
},
saveToServer : function() {
this._model.save(this.getReverseMapping, {
success : function(model, response) {
...
},
error : function(model, response) {
...
}
})
}
Since your overridden save automatically copies the JSON you pass in to options.data, Backbone.sync will use it to post.
The answer by Brendan Delumpa works, but it over-complicates things.
Don't do this in your save method. You don't want to copy over these parameter checks each time (and what if they somehow change in Backbone?).
Instead, overwrite the sync method in your model like this:
var MyModel = Backbone.Model.extend({
...,
sync: function (method, model, options) {
if (method === 'create' || method === 'update') {
// get data from model, manipulate and store in "data" variable
// ...
options.data = JSON.stringify(data);
options.contentType = 'application/json';
}
return Backbone.Model.prototype.sync.apply(this, arguments);
}
});
That's all there is to it when you need to "prepare" the data in a server-ready format.