CODEWITHSUNDEEP
extjs
gbegley
gbegley

Reputation: 2679

ExtJS Model with repeating structures

What patterns have been successful when mapping a model with a few repeating structures. I have to model and create a grid view a record with has a few columns which are basically the same repeating structure. 

Ext.define('Ep.mm.model.MyComparison', {
var derived = function(val,)
    extend: 'Ext.data.Model',
    fields : [
        {name:'id',type:'string'},
        {name:'count',type:'number'},
        {name:'special',type:'number'},
        {name:'A_a',type:'number'},
        {name:'A_b',type:'number'}
        {name:'A_derived',renderer = function(val,meta,rec){return rec.get('A_b')-rec.get('A_a')}}
        {name:'B_a',type:'number'},
        {name:'B_b',type:'number'}
        {name:'B_derived',renderer = function(val,meta,rec){return rec.get('B_b')-rec.get('B_a')}}
        {name:'C_a',type:'number'},
        {name:'C_b',type:'number'}
        {name:'C_derived',renderer = function(val,meta,rec){return rec.get('C_b')-rec.get('C_a')}}
    ]
});

I am likely to end up with Server models/stores that differ only in the number of times this structure repeats (A) (A,B) (A,B,C,D). Is there a way to use a common model for each of A,B,C,D and just re-use the common model as the type. This is something akin to a 'nested' structure. 

Ext.define('MyType',{
   extend :'Ext.data.Model',
   fields : [
      {name : 'a', type:'number'},
      {name : 'b', type:'number'},
      {  name : 'derived', 
         convert : function(value, record) {
            return record.get('a') - record.get('b');
         }
      }
   ]
}

Then MyComparison would be defined as 

Ext.define('Ep.mm.model.MyComparison',{
   extend : 'Ext'data.Model',
   fields : [
      {name:'A', type:'MyType'}
      {name:'B', type:'MyType'}
      {name:'C', type:'MyType'}
   ]
});

I know this isn't quite right, but this is sort of the functionality I am trying to create. Perhaps using the 'hasOne' association type?

Upvotes: 1

Views: 139

Answers (2)

Peter Ivan
Peter Ivan

Reputation: 1521

I'd say you want functionality of a field type:

Ext.data.Types.A_DERIVED = {
    convert: function(v, data) {
        return rec.get('A_b')-rec.get('A_a');
    },
    type: 'number'
};

Then use it as a type of A_derived field:

Ext.define('Ep.mm.model.MyComparison', {
    extend: 'Ext.data.Model',
    fields: [
        {name:'id',type:'string'},
        {name:'A_a',type:'number'},
        {name:'A_b',type:'number'},
        {name:'A_derived', type: 'Ext.data.Types.A_DERIVED'}
    ]
});

Afterthoughts:
- Maybe you would like to aggregate all A_* data into one field? See documentation for an example.
- There is a trouble when you want to use the same mechanism with B_derived because there is no way of supplying B into convert function. A dirty hack might be to set the defaultValue to B and to bind the field to null data. Then v would be read from defaultValue.

Upvotes: 0

Evan Trimboli
Evan Trimboli

Reputation: 30082

Yes, you can extend your own model classes:

Ext.define('Base', {
    extend: 'Ext.data.Model',
    fields: ['name']
});

Ext.define('Child', {
    extend: 'Base',
    fields: ['age']
});

var o = new Child({
    name: 'Foo',
    age: 100
});
console.log(rec.get('name'), rec.get('age'));

As a sidenote, models don't have renderers. You're probably looking for the convert function on the field, here.

Upvotes: 1

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