strictHttp is an alternate $http.post service that checks for values before making the $http call.

stricthttp.js

var app = angular.module('app',[]);
app.factory('strictHttp', function ($http) {
	return {
		post: function(url, params, req, config){
			var invalid;
			for(var p in params){
				if(req.indexOf(p) > -1 && (params[p] === '' || params[p] === undefined)){
					invalid = 1;
				}
			}
			if(!invalid){
				return $http.post(url, params, config);
			}
			return { 
				success : function(f){
					f('Request Failed');
				}
			};
		}
	}
  });
  
app.controller('Controller1',function($scope, strictHttp){
  var params = {}
  params.first = 'test';
  params.second = '';
  strictHttp('http://apiurl.io', params, ['first', 'second'], {}).success(function(data){
    console.log(data)
  })
});