xmlHttpRequest AJAX POST Reading the Posted value in MVC Controller - javascript

Been struggling to find a solution to this one, despite the mass of useful information out there.
I have the following Javascript Function that is sending an AJAX call to my controller.
var ajax = new XMLHttpRequest();
var posts = document.getElementsByClassName('postLink');
var sendstr = "";
for (var i = 0; i < posts.length; i++) {
sendstr += ',';
sendstr += posts[i].attributes.getNamedItem('onmouseup').value.substr(9, 1);
}
ajax.onreadystatechange = function () {
if (ajax.readyState == 4 && ajax.status == 200) {
var posts = JSON.parse(ajax.responseText);
addPostToList(posts.Title, posts.Description, posts.postID);
}
}
ajax.open('POST', '#Url.Action("SAR", "posts")', true);
ajax.setRequestHeader('Content-type', 'text/plain');
ajax.setRequestHeader('Content-length', sendstr.length);
ajax.setRequestHeader('Connection', 'close');
ajax.send(encodeURIComponent(sendstr));
The controller is as follows...
[HttpPost]
public ActionResult SAR(string r)
{
var s = Request.QueryString[0];
return Content(Post.JSONSerialize());
}
I have tried a number of different Data types as the Parameter and have still not received anything of use... I have also tried Request.Param, request.queryString, request.Form and a number of other 'solutions' that i have found on the web, it is passing only a comma seperated list of integers to the controller, stored as a string. How do i read this value when it has been sent off to the controller?
~I do not want a JQuery or JS Framework solution, i would like a native Javascript solution.

1.- Use JSON as your content-type.
2.- The string you are sending back has to match the parameter name you are expecting on your controller.
change your sendstr to the following format:
//Where r is the name of your parameter on the controller.
var sendstr = '{"r":"STRING YOU WANT TO RETURN"}';
then change your ajax configuration to be
ajax.open('POST', '#Url.Action("SAR","Controller")', true);
ajax.setRequestHeader('Content-Type', 'application/json; charset=utf-8');
ajax.setRequestHeader('Content-Length', sendstr.length);
ajax.send(sendstr);
I hope this works for you :)

Related

why does xmlHttpRequest.Open only work when I input a string?

I'm trying to call a Restful service on my localhost. I am doing it this way because It's an asynchronous call. The appropriate Url plus the Uri-template to call my service is this:
"http://localhost:65016/Service1.svc/SN?lower=200&upper=300"
on the line where I try to open ( xhttp.open ), my client page only receives the proper data whenever I literally insert the url like this:
xhttp.open("GET", "http://localhost:65016/Service1.svc/SN?lower=200&upper=300" , true);
but I need the 200 and 300 numbers to be user input so I tried these two things:
I first tried grabbing the user input and simply concatenating it to the base URL in between the URi template like this:
<script>
function ServiceCall()
{
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function ()
{
if (xhttp.readyState == 4 && xhttp.status == 200) {
var ans = document.getElementById("secretNum");
ans.innerHTML = xhttp.responseText;
}
}
var base_uri = "http://localhost:65016/Service1.svc/";
// grab the lower number
var ln = document.getElementById("LN").firstChild;
var LN = ln.nodeValue;
// grab upper number
var un = document.getElementById("UN").firstChild;
var UN = un.nodeValue;
//complete
var URL = base_uri + "SN?lower=" + LN + "&upper=" + UN;
xhttp.open("GET", URL, true);
xhttp.setRequestHeader("Content-type", "application/json");
xhttp.send();
}
</script>
Doesn't work. So i tried looking at the documentation for the xmlHttpRequest.open, and I saw that the parameter had to be a URL. so I tried using the URL(string) function and using the output as a parameter and that didn't work either.
Any help please?
Thank you. I it helped to look at the network request. I was simply using the wrong syntax to obtain the value inside of the html input tag.
var ln = document.getElementById("LN").value;
returns the real value inside of html input tag given by the user input.
I'm answering my own question because this is a homework assignment.
(Not that I was cheating. Answering this is far from solving the homework)

Values from vanilla JavaScript to PHP using AJAX

I want to know how to send something to php using ajax and vanilla javascript.
I ask you because I just found jQuery solution.
I know that if I want to recieve something it should looks like this:
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
this.responseText; // This is my response
}
};
xhttp.open("GET", "phpfile.php", true);
xhttp.send();
Someone can explain or send me to solution because I couldn't find anything.
First method
To send data from JavaScript to PHP (or any other script) should be just as you found out:
xhttp.setRequestHeader('Content-type', 'application/json');
xhttp.send(JSON.stringify(params));
where params is some JavaScript variable. application/json is the datatype for JSON data.
On the PHP side, you were also correct: use JSON_decode() to get a PHP-equivalent to the JavaScript data you sent.
Second method (only for GET requests)
GET data is encoded in the URL, so an alternative way is to encode the data directly into the URL of the PHP script. (Don't do this for sensitive data.)
Javascript:
xhttp.open("GET", "phpfile.php?x=2&y=3&z=4");
PHP:
$x = $_GET["x"];
$y = $_GET["y"];
$z = $_GET["z"];
Because you seemed unclear on how to send multiple variables using the first method:
If you want to send multiple variables, put it into an object or array (because JSON.stringify() only takes one (data) argument, not a comma-separated list of arguments).
// for example, to send the variables x, y, z
var xValue = 2;
var yValue = 3;
var zValue = 4;
xhttp.setRequestHeader('Content-type', 'application/json');
xhttp.send(JSON.stringify({ x: xValue, y: yValue, z: zValue }));
PHP:
$data = json_decode($_GET);
echo $data->x; // 2
echo $data->y; // 3
echo $data->z; // 4;
(disclaimer: code is untested; I'm not sure if data is received into the $_GET variable. Use json_decode() on the variable that PHP receives JSON data from.)

How to set multiple HTTP headers in JavaScript get () method

I have been searching the total Internet from around a week and finally decided to post here. I want to send an HTTP get request to an API with two headers for authentication. These are custom headers and need to be sent at once.
I have tried the following code but it never gives me success. The API returns a JSON file which will have parameters like "title", "description". The URL and headers work fine, when I tried it using hurl.it.
This is the code. Please suggest some answer to solve this problem. And one more thing is, I want to do it using JavaScript only, no jQuery, AJAX, or AngularJS.
var xmlhttp = new XMLHttpRequest();
var url = "https://affiliate- api.flipkart.net/affiliate/offers/v1/dotd/json";
xmlhttp.onreadystatechange = function() {
if(xmlhttp.readyState == 4 &&xmlhttp.status==200) {
var myArr = JSON.parse(xmlhttp.responseText);
function display(arr) {
var i;
var out = " ";
for(i = 0; i < arr.length;i++) {
out += "<p>title:" + arr.dotd[i].title + "<br>description:" + arr.dotd[i].description + "<br></p>";
}
document.getElementById("p1").innerHTML = out;
}
}
else {
alert(xmlhttp.status);
}
};
xmlhttp.open("GET", url, true);
xmlhttp.setRequestHeader("Fk-Affiliate- Token","xxxxxxxxxxxxxxxxx");
xmlhttp.setRequestHeader("Fk-Affiliate-Id","xxxxxxxxx");
xmlhttp.send();

Setting server response data to a variable to work with

Hey guys I am using a executePostHttpRequest function that looks exactly like the code posted below. Currently when I run the function I get a server response with the appropriate data but I am not sure how I can work with the response data? how do I store it in to a variable to work with?
Javascript executePostHttpRequest
function executePostHttpRequest(url, toSend, async) {
console.log("====== POST request content ======");
console.log(toSend);
var xmlhttp = new XMLHttpRequest(); // new HttpRequest instance
xmlhttp.open("POST", url, async);
xmlhttp.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
xmlhttp.setRequestHeader("Content-length", toSend.length);
xmlhttp.send(toSend);
console.log("====== Sent POST request ======");
}
Here is what I am doing to execute it. Using Javascript
var searchCriteria = JSON.stringify({
displayName : search_term
});
console.log("Search: "+searchCriteria) //Search: {"name":"John, Doe"}
var response = executePostHttpRequest("/web/search", searchCriteria, true);
console.log(response) //undefined
So currently the console.log for response shows undefined. But if I take a look at the network tab on Chrome Dev Tools and look at the /web/search call I see a JSON string that came back that looks something like this.
[{"id":"1","email":"john.doe#dm.com","name":"John, Doe"}]
I'd like to be able to display the data from this response to a HTML page by doing something like this.
$("#id").html(response.id);
$("#name").html(response.name);
$("#email").html(response.email);
I tried taking another route and using Jquery POST instead by doing something like this.
var searchCriteria = JSON.stringify({
displayName : search_term
});
console.log("Search: "+searchCriteria) //Search: {"name":"John, Doe"}
$.post("/web/search", {
sendValue : searchCriteria
}, function(data) {
$.each(data, function(i, d) {
console.log(d.name);
});
}, 'json').error(function() {
alert("There was an error searching users! Please contact administrator.");
});
But for some reason when this runs I get the "There was an error" with no response from the server.
Could someone assist me with this? Thank you for taking your time to read it.
Your executePostHttpRequest function doesn't do anything with the data it's receiving. You would have to add an event listener to the XMLHttpRequest to get it:
function getPostData(url, toSend, async, method) {
// Create new request
var xhr = new XMLHttpRequest()
// Set parameters
xhr.open('POST', url, async)
// Add event listener
xhr.onreadystatechange = function () {
// Check if finished
if (xhr.readyState == 4 && xhr.status == 200) {
// Do something with data
method(xhr.responseText);
}
}
}
I've added the method parameter for you to add a function as parameter.
Here's an example of what you were trying to do:
function displayStuff(jsonString) {
// Parse JSON string
var data = JSON.parse(jsonString)
// Loop over data
for (var i = 0; i < data.length; i++) {
// Get element
var element = data[i]
// Do something with its attributes
console.log(element.id)
console.log(element.name)
}
}
getPostData('/web/search', searchCriteria, true, displayStuff)

How to get JSON object in Servlet from JSP?

In JSP page I have written:
var sel = document.getElementById("Wimax");
var ip = sel.options[sel.selectedIndex].value;
var param;
var url = 'ConfigurationServlet?ActionID=Configuration_Physical_Get';
httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
httpRequest.open("POST", url, true);
httpRequest.onreadystatechange = handler(){
if (httpRequest.readyState == 4) {
if (httpRequest.status == 200) {
param = 'ip='+ip;
param += 'mmv='+mmv;
param += "tab="+tab;
}};
httpRequest.send(param);
I want this param variable in my ConfigurationServlet. Can anyone tell me how to get this json object in servlet?
Update: I changed my statements and now it is showing status code as 200.
var index = document.getElementById("Wimax").selectedIndex;
var ip = document.getElementById("Wimax").options[index].text;
httpReq = GetXmlHttpObject();
alert(httpReq);
var param = "ip=" + ip;
param += "&mmv=" + mmv;
param += "&tab=" + tab;
alert("param "+param);
var url="http://localhost:8080/WiMaxNM/ConfigurationServlet?ActionID=Configuration_Physical_Get";
url = url+"?"+param;
httpReq.open("GET",url,true);
alert("httpReq "+httpReq);
httpReq.onreadystatechange = handler;
httpReq.send(null);
But new problem has occured. Control is not at all going to the servlet action ID as specified in url. Please tell me what is wrong here.
The code in the handler will only be invoked AFTER the request is been sent. You need to populate param before this. You would also need to concatentate separate parameters by &.
Thus, e.g.
// ...
httpRequest.onreadystatechange = handler() {
// Write code here which should be executed when the request state has changed.
if (httpRequest.readyState == 4) {
// Write code here which should be executed when the request is completed.
if (httpRequest.status == 200) {
// Write code here which should be executed when the request is succesful.
}
}
};
param = 'ip=' + ip;
param += '&mmv=' + mmv;
param += "&tab=" + tab;
httpRequest.send(param);
Then you can access them in the servlet the usual HttpServletRequest#getParameter() way.
That said, the Ajax code you posted there will only work in Microsoft Internet Explorer, not in all the four other major webbrowsers the world is aware of. In other words, your Javascript code won't work for about half of the people in the world.
I suggest to have a look at jQuery to lessen all the verbose work and bridge the crossbrowser compatibility pains. All your code could be easily replaced by
var params = {
ip: $("Wimax").val();
mmv: mmv,
tab: tab
};
$.post('ConfigurationServlet?ActionID=Configuration_Physical_Get', params);
And still work in all webbrowsers!
Update: as per your update, the final URL is plain wrong. The ? denotes a start of the query string. You already have one in your URL. You should use & to chain parameters in the query string. I.e.
url = url + "&" + param;

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