extjs4 - is there a non json/xml writer for proxies? - extjs

Question

I'm building some models to interact with an existing API from a previous project.
The API relies on standard POST methods to save the data.
I've configured a model and proxy up to the point where it does push the data onto the server but there only seems to be two writer types, json & xml.
proxy: {
/* ... */
reader: {
type: 'json',
root: 'results'
},
writer: {
type: '???' // <-- can only see json or xml in the docs
}
}
Isn't there a standard POST writer that simply submits data in post fields?
I'm surprised that wouldn't be a standard writer type.
(Parsing the json format wouldn't be too hard to implement but that would mean updating a lot of the old api files.)

Answer 1

Ok, I was able to create that writer quite easily by checking the existing writers' source code.
One thing those existing writers are able to do - and that may be why the dev team only implemented a json and xml version - is that they can push multiple records at once.
That could be implemented in POST but would be a bit more complicated.
This writer will work if you're trying to push a single model to an api using POST:
Ext.define('Ext.data.writer.SinglePost', {
extend: 'Ext.data.writer.Writer',
alternateClassName: 'Ext.data.SinglePostWriter',
alias: 'writer.singlepost',
writeRecords: function(request, data) {
request.params = data[0];
return request;
}
});
and the use this for the writer in the proxy:
writer: {
type: 'singlepost'
}

Answer 2

Based on Ben answer I've implemented my own writer that will collect all properties of all models into arrays.
For example if you have model like with some fields:
fields:[
{name:'id', type:'int'}
{name:'name', type:'string'}
{name:'age', type:'date'}
]
A request string will be
id=1&id=2&id=...&name=oleks&name=max&name=...&age=...
Code:
Ext.define('Ext.data.writer.SinglePost', {
extend: 'Ext.data.writer.Writer',
alternateClassName: 'Ext.data.SinglePostWriter',
alias: 'writer.singlepost',
writeRecords: function(request, data) {
if(data && data[0]){
var keys = [];
for(var key in data[0]){
keys.push(key);
}
for(var i=0;i<keys.length;i++){
request.params[keys[i]] = [];
for(var j=0;j<data.length;j++){
request.params[keys[i]].push((data[j])[keys[i]]);
}
}
}
return request;
}
});

Answer 3

For Sencha touch 2.0, change the writeRecords method to:
writeRecords: function (request, data) {
var params = request.getParams() || {};
Ext.apply(params, data[0]);
request.setParams(params);
return request;
}

Answer 4

Here's my version, adapted from answers above:
// Subclass the original XmlWriter
Ext.define('MyApp.utils.data.writer.XmlInAPostParameter', {
extend : 'Ext.data.writer.Xml',
// give it an alias to use in writer 'type' property
alias : 'writer.xml_in_a_post_parameter',
// override the original method
writeRecords : function(request, data) {
// call the overriden method - it will put the data that I
// want into request.xmlData
this.callParent(arguments);
// copy the data in request.xmlData. In this case the XML
// data will always be in the parameter called 'XML'
Ext.apply(request.params, {
XML: request.xmlData
});
// Already copied the request payload and will not send it,
// so we delete it from the request
delete request.xmlData;
// return the modified request object
return request;
}
});
Ext.define("MyApp.model.MyModel", {
extend : "Ext.data.Model",
requires : [
'MyApp.utils.data.writer.XmlInAPostParameter'
],
fields : [ 'field_A', 'field_B' ],
proxy : {
type : 'ajax',
api : {
read : '/mymodel/read.whatever',
update : '/mymodel/write.whatever'
},
reader : {
type : 'xml'
},
writer : {
// use the alias we registered before
type : 'xml_in_a_post_parameter'
}
}
});