我将如何从json文件创建模型？ （ExtJS的）

Question

This the model that I want to create using json file

Ext.define('Users', {
    extend: 'Ext.data.Model',
    fields: [{name: 'user_id',  type: 'int'},
    {name: 'user_name',  type: 'string'}]
});

What do I have to do in order to automatically create this model, based on the content of a json response from the server?

Answer 1

In order to have the model created automatically, you need to include the metaData field with your Json data. metaData can be used to describe all of the fields for the Model.

In the ExtJS 4.1 documentation - Ext.data.reader.Json has a section called Response MetaData which describes basic use of this feature.

Answer 2

You should be able to pull down some json with fields and or some format that can be transformed into that format pretty easily.

1. Make call to service to get model's fields. Might need to define some chain that first calls model service and performs subsequent steps after.

2. Build model's field array w/ fields results from #1. May need to transform data based on response in #1.

   var fields = response.fields;

3. Define model based on fields in Store's constructor

    var store = Ext.create('Ext.data.Store', { constructor: function () { var model = Ext.define("Users", { extend: "Ext.data.Model", fields: fields }); this.model = model.$className; this.callParent(arguments); } }); 

Answer 3

I only use the jsonp, which loads an json file and parses it automatically, don't know if Ext.Ajax does this, too.

But you would do something like this:

definition.json:

{
  "name": "User",
  "fields": [
    { "name": "user_id"  , "type": "int"    },
    { "name": "user_name", "type": "string" }
  ]
}

load it:

Ext.Ajax.request({
  url    : "..../definition.json"
  success: function( res ) {
    Ext.define( res.name, {
      extend: 'Ext.data.Model',
      fields: res.fields
    }, function() {
      Ext.create( 'somestore', { model: res.name });
    });
  }
});