Default $resource POST data

This is not really the angular way to do such a thing as you lose data consistency if you do it and it doesn't reflect in your model.

Why?

The resource factory creates the object and uses object instance data as POST. I have looked at the documentation and angular-resource.js and there doesn't seem to be a way to specify any default custom properties for the object being created by resource without modifying angular-resource.js.

What you can do is:

services.factory("Product", function($resource) {
    return $resource("http://someUrl", {}, {
        get   : {method: "GET", params: {productId: "-1"}},
        update: {method : "POST"}
    });
});

and in your controller:

$scope.product = {}; // your product data initialization stuff
$scope.product.someDataKey = 'someDataValue'; // add your default data

var product = new Product($scope.product);
product.$update();

I think it will depend on how you call the update function. If you read the angular main page's tutorial, under "Wire up a Backend", the mongolab.js provides a 'Project' factory. Copied verbatim:

angular.module('mongolab', ['ngResource']).
factory('Project', function($resource) {
  var Project = $resource('https://api.mongolab.com/api/1/databases' +
      '/angularjs/collections/projects/:id',
      { apiKey: '4f847ad3e4b08a2eed5f3b54' }, {
        update: { method: 'PUT' }
      }
  );

  Project.prototype.update = function(cb) {
    return Project.update({id: this._id.$oid},
        angular.extend({}, this, {_id:undefined}), cb);
  };

  Project.prototype.destroy = function(cb) {
    return Project.remove({id: this._id.$oid}, cb);
  };

  return Project;
});

The usage is that you first get an instance of the Project:

project = Project.get({id:1});

Then do an update after some changes:

project.update(someFunction);

In your case, you can change the update to always add the data you need:

Product.prototype.update = function(cb) {
  return Product.update({},
      angular.extend({}, this, {someDataKey: someDataValue}), cb);
};

Otherwise, you can most likely put the key/value pair in the params:

    update: {method : "POST", params:{someDataKey: someDataValue}}

It will be POSTed with the key/value pair in the URL, but most app servers nowadays will throw the pair into the params object anyway.

Wrapper function will work.

function myPost(data) {
  return $http.post('http://google.com', angular.extend({default: 'value'}, data))
}

myPost().success(function(response) { ... });

Might this solve your problem?

services.factory("Product", function($resource) {
  return $resource("http://someUrl", {}, {
    get   : {method: "GET", params: {productId: "-1"}},
    update: {method : "POST", params:{}, data: {someDataKey: someDataValue}}
  });
});
services.factory("DefaultProduct", function(Product) {
  return function(){
     return new Product({
        data:"default";
     });
  };
});
services.controller("ProductCTRL",function($scope,DefaultProduct){
  $scope.product = new DefaultProduct();
});

You can just merge your params with the default. Everything not available in params will be provided by the default object. Everything available will be overwritten by myParams

services.factory("Product", function($resource) {
    return $resource("http://someUrl", {}, {
        get   : {method: "GET", params: {productId: "-1"}},
        update: {method : "POST", params:angular.extend(myDefault, myParams);}
    });
});

where myParams would be your list of variables and myDefault your default values as a json object.