backbone - fetched model, set an attribute(modify),then save model, it should update but sending POST request

Question

i created mywebsite having 2 types of users admin,user . So, i created 3pages mainpag.html, admin.html,user.html . and separate models,views,collections,routers.js files for each of them . So,after logging in, as i am sending to separate html pages with different models, i cant automatically get user model . so i did like this :

First, i made ajax call to server,asking for the _id (username in session,so i can get id)

from the id, i fetched the model ,by model.fetch(), then i got my usermodel with all attributes.

then in the success callback of fetch , i did model.save({weight : "somevalue"}) . According to me, it should update right , as the model is already available,that attribute weight also available with some old value, but it is sending POST request , also when i tried model.isNew() , it returned true . Where am i wrong ? how can i update my model ? I will post more details if required .

More details :

if i remove that save method, then i am getting correct attributes in the model.

if i dont remove that save method, that success and error callbacks are also appearing as attributes in the model.

Code :

   addWeight : (e)->
    arr=new Array()
    arr['_id']=app._id
    console.log "asdasd"
    console.log arr
    console.log arr['_id']
    @user_model =new UserModel(arr)
    @user_model.fetch({
      success : (model,res,options) =>
        console.log model
        console.log res
        arr=new Array()
        arr['_id']=e.target.id
        #arr['action']='weight' #means , update weight
        #@user_model.setArr(arr)  
        #@user_model.set({weight : arr['_id']}) 
        console.log "new  : "+@user_model.isNew()
        @user_model.save({weight : e.target.id})
        #@user_model.save({
        #  success : (model,res,options) =>
        #    console.log "model updated: "+JSON.stringify(model)
        #    console.log "Res : "+JSON.stringify(res)
        #  error : (model,res,options) =>
        #    console.log "Error : "+JSON.stringify(res)
        #})

      error : (model,res,options) =>
        console.log "Error "  

    })

the above code is written in coffeescript, so even if u dont know coffeescript,dont worry, u can understand easily, and those # means, it is a comment. here we follow indentation instead of braces.

one more doubt, a model's url must be changed dynamically according to the requirement , right ? what is the best way to achieve that ? i am doing like this :

i am populating "array" containing the required fields that should be present in the url . In model,s init func, i am using @arr=arr,thenin url's function , i check like this .

   url : -> 
     if @arr['id'] 
     "/user/#{@id}"

Is my approach right, or any better approach is there for dynamicaly setting url's . Or can i directly set the url's like this :

    @user_model.setUrl "/someurl/someid"  //this setUrl method is available in model's definition
    @user_model.fetch() or save() or watever that needs url

thanks

Kaleb F. Kaleb F. · Accepted Answer · 2012-04-18T06:19:54

Just a hunch, but you mentioned that you call model.fetch() to retrieve the _id field. Be sure to either return an id field instead _id (notice the underscore).

The call to model.isNew() returning true is an indicator that the id property was never set from the model.fetch() call.

I look forward to a possible further explanation with your code... Looking at your code:

/* The model needs an 'id' attribute in order to marked as not new */ 
@user_model = new UserModel(id: arr['_id'])

backbone - fetched model, set an attribute(modify),then save model, it should update but sending POST request

2 Answers