Develop Reference

Django - Sending POST request from javascript

I have a JS event-triggered function which goal is send a POST request in order to update some objects in my database. The event which triggers the function is a drop-event, so i initially avoided using forms to pass my request, but tell me if i did wrong.
Big Edit:
I found that my mistake was to not include the csrf_token on my post request.
However, i still have an error: my post request comes in empty when i do print(request.POST) on my django view.
My JS file:
function getCookie(name) {
var cookieValue = null;
if (document.cookie && document.cookie !== '') {
var cookies = document.cookie.split(';');
for (var i = 0; i < cookies.length; i++) {
var cookie = cookies[i].trim();
// Does this cookie string begin with the name we want?
if (cookie.substring(0, name.length + 1) === (name + '=')) {
cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
break;
}
}
}
return cookieValue;
}
var csrftoken = getCookie('csrftoken');
const dragDrop = function (e) {
e.preventDefault()
const droppedElId = e.dataTransfer.getData('Text/html').split('__id-')[1]
const request = new XMLHttpRequest()
request.open('POST', '', true)
request.setRequestHeader('X-CSRFToken', csrftoken)
request.setRequestHeader('Content-Type', 'application/json')
// request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8')
request.send(JSON.stringify({
"request_name":"change-extra-fields",
"type":"increase",
"id":droppedElId,
}))
}
The query-dict of the request.POST is empty when i do this. However, the request works if i change the Content-Type header to application/x-www-form-urlencoded, but it puts everything on the same key.
Example:
Result with 'application/json':
<QueryDict: {}>
Result with 'application/x-www-form-urlencoded':
<QueryDict: {'{"request_name":"change-extra-fields","type":"increase","id":"8"}': ['']}>
Anyways, i think that 'application/json' should be working and i have no idea why it isn't..

There is a typo I think
request.setRequestHeader('Content-Type', 'application/json');
As you mentioned in comments, your post request required you to be authenticated.
So, you first need to authenticate/login to the site(using another Ajax call perhaps). If the site supports jwt/api authentication you would get a token back which you have to send in attached with header in next (post)request. it would be something like this
xhr.setRequestHeader('Authorization', 'Bearer arandombereartoken');
if the site uses session/cookie authentication then I suggest consider using jQuery and its Ajax functions.
I this this(2nd one) should be helpful.
UPDATE:
if you want to get data as application/json you have to look in the body of the request
if request.method == "POST":
print(request.body)
this would give you a byte object. you have load it to a json if you want json. request.POST is only for Content-Type 'application/x-www-form-urlencoded'

Tableau REST API: Using Javascript to get the Token

I am a complete beginner with REST API and I could not figure out how I am to proceed.
I installed Postman and was successfully able to get the Token, but I am not sure how to send the raw XML payload in javascript.
<tsRequest>
<credentials name ="XXX" password="YYY" >
<site contenturl = "" />
</credentials>
</tsRequest>
I have :
httpRequest.open('POST', 'http://MY-SERVER/api/2.4/auth/signin', false);
httpRequest.setRequestHeader("Content-type", "application/xml");
Not sure how to add the xml payload. I have access to a Tableau Server(MY-SERVER) and everything.
Any help would be greatly appreciated!
Thank you!

You are getting closer, you just need to use the send method to send your XML: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/send
Just make sure that your XML is properly encoded in javascript when you're inputting it. So if you are using double quotes inside your XML, make sure you have single quotes to declare your string in javascript (e.g.) var data = '<credentials name="XXX" >';
Related: Send POST data using XMLHttpRequest

In addition to #AnilRedshift answer, here's the functioning code:
login_details=[];
function getToken() {
var url = "http://yourServerAddress/api/2.0/auth/signin";
var params = "<tsRequest><credentials name='Username' password='UserPassword' ><site contentUrl='' /></credentials></tsRequest>";
return zuo = new Promise(function(resolve,reject){
var xhr = new XMLHttpRequest();
xhr.open("POST", url, true);
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.withCredentials = true;
xhr.onload= function(){
if (this.status === 200) {
var parsed_xml = JSON.parse(JSON.stringify(x2js.xml_str2json(xhr.responseText)))
login_details.push(parsed_xml.tsResponse.credentials._token); login_details.push(parsed_xml.tsResponse.credentials.site._id);
resolve(login_details);
}
}
xhr.onerror=reject;
xhr.send();
})
}
function getWorkbooks(){
var url = "http://serveraddress//api/2.3/sites/"+login_details[1]+"/workbooks?pageSize=1000";
return zuo = new Promise(function(resolve,reject){
var xhr = new XMLHttpRequest();
xhr.open("GET", url, true);
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.setRequestHeader("X-Tableau-Auth",login_details[0]);
xhr.onload= function(){
if (this.status === 200) {
var workbooks = JSON.parse(JSON.stringify(x2js.xml_str2json(xhr.responseText)))
for (var f=0;f<workbooks.tsResponse.workbooks.workbook.length;f++){
if(workbooks.tsResponse.workbooks.workbook[f].project._name=="Default"){
workbooks_list.push(workbooks.tsResponse.workbooks.workbook[f]._id)
}
resolve();
}
}
}
xhr.onerror= function(){
console.log(xhr.responseText);
}
xhr.send();
})
}
Invoke the code with:
getToken()
.then(function(login_details){
console.log(login_details[0]+"/"+login_details[1]);
})
.then(function(){
getWorkbooks();
})
getToken() function gets the login token which has to be used in all subsequent calls.
getWorkbooks() fetches all dashboards in 'Default' project but this kind of request can be used for all GET type requests.
Please note that this approach uses hardcoded values for password and username which is generally not the best practice. It would be way better to use server side scripting or encrypting (better but still with flavs).
You can find whole step by step tutorial and running code here:
http://meowbi.com/2017/10/23/tableau-fields-definition-undocumented-api/

POST data from a client javascript page to a node server

Is it possible to POST data from a client javascript page to a node server (server.js) using an AJAX XMLHttpRequest()? What I am looking for is javascript code that will receive the data on the node server, specifically the values for member_nm ("newName") and member_email ("mail#google.com"). I control the server. I also understand that I can also use GET to send the text values by means of a querystring. Below is the request that is sent from the client javascript page by means of an event handler:
document.getElementById("btnAddMember").addEventListener("click", function()
{
var request = new XMLHttpRequest();
var path = "/Users/Admin/WebstormProjects/projectName/server.js";
request.onreadystatechange = function()
{
if ( request.readyState === 4 && request.status == 200 )
{
request.setRequestHeader("Content-Type", "text/plain; charset=UTF-8");
request.open("POST", path, true);
request.send("member_nm=newName&member_email=mail#google.com");
}
};
});

You need to setup your server to accept this post request, the easiest will be to use Express with bodyParser middleware, like this :
var express = require('express');
var server=express();
var bodyParser= require('body-parser');
server.use(bodyParser.json());
server.post('/', function(req, res){
if(req.body){
// get the params from req.body.paramName
}
});
server.listen(8222, function(){
console.log('listening for requests ..')
});
In your client code change the 'path' to point to the server url:port, and I will put these outside of the onReadyStateChange:
request.setRequestHeader("Content-Type", "text/plain; charset=UTF-8");
request.open("POST", path, true);
request.send("member_nm=newName&member_email=mail#google.com");

This is a working solution on how to POST variables from a client javascript file to a Node server using Express. The POST is initiated on the client by means of an event handler, btnAddMember. txtName.value and txtMembershipType.value contain the values to be posted. Note the syntax that is necessary to parse the values correctly. member_nm and member_type will be used to reference the properties on the Node server. First the client javascript:
document.getElementById("btnAddMember").addEventListener("click", function()
{
var request = new XMLHttpRequest();
var path = "http://0.0.0.0:0000"; // enter your server ip and port number
request.open("POST", path, true); // true = asynchronous
request.setRequestHeader("Content-Type", "application/json; charset=UTF-8");
var text= '{"member_nm":"' + txtName.value + '","member_type":"' + txtMembershipType.value + '"}';
request.send ( text );
});
Next is the server side code. Note that bodyParser must now be added to your project as a node_module. This can be done through the node program manager (npm). The POST statement basically parses the req.body from a JSON format to a javascript object format using a variable called 'member'. The code then logs the posted values for the two variables, member_nm and member_type. Finally a response status is sent to the client if the POST is successful.
var bodyParser = require("body-parser");
...
app.use(bodyParser.text({ type: "application/json" }));
...
// receive the POST from the client javascript file
app.post("/", function (req, res)
{
if (req.body)
{
var member = JSON.parse( req.body ); // parse req.body as an object
console.log("member_nm: " + member.member_nm );
console.log("member_type: " + member.member_type );
res.sendStatus(200); // success status
}
else
{
res.sendStatus(400); // error status
}
});

How do i correctly format parameters passed server-side using javascript?

I cannot figure out how to get the following code working in my little demo ASP.NET application, and am hoping someone here can help.
Here is the javascript:
function checkUserName() {
var request = createRequest();
if (request == null) {
alert("Unable to create request.");
} else {
var theName = document.getElementById("username").value;
var userName = escape(theName);
var url = "Default.aspx/CheckName";
request.onreadystatechange = createStateChangeCallback(request);
request.open("GET", url, true);
request.setRequestHeader("Content-Type", "application/json");
//none of my attempts to set the 'values' parameter work
var values = //JSON.stringify({userName:"userName"}); //"{userName:'temp name'}"; //JSON.stringify({ "userName":userName });
request.send(values);
}
}
Here is the method in my *.aspx.cs class:
[WebMethod]
[ScriptMethod(UseHttpGet=true)]
public static string CheckName(string userName)
{
string s = "userName";
return s + " modified backstage";
}
When this code runs I receive this exception:
---------------------------
Message from webpage
---------------------------
{"Message":"Invalid web service call, missing value for parameter: \u0027userName\u0027.","StackTrace":" at System.Web.Script.Services.WebServiceMethodData.CallMethod(Object target, IDictionary`2 parameters)\r\n at System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(Object target, IDictionary`2 parameters)\r\n at System.Web.Script.Services.RestHandler.InvokeMethod(HttpContext context, WebServiceMethodData methodData, IDictionary`2 rawParams)\r\n at System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext context, WebServiceMethodData methodData)","ExceptionType":"System.InvalidOperationException"}
---------------------------
OK
---------------------------
I started searching here, then went on to several threads on SO, trying quite a few combinations of quotation marks and key-value pairs, but nothing I've tried has worked.
When I remove the parameter from the C# method and request.send(), I get a response in my JS callback that I can work with. But as soon as I try to do something with parameters, I get the above exception. I'd like to know how to do this without using jQuery, if possible.
Thanks in advance.
FINAL VERSION
Using Alexei's advice, I ended up with the following, which works. The URL was missing the apostrophes on either end of the parameter value; this was keeping the call from going through.
function checkUserName() {
var request = createRequest();
if (request == null) {
alert("Unable to create request.");
} else {
var theName = document.getElementById("username").value;
var userName = encodeURIComponent(theName);
var url = "Default.aspx/CheckName?name='" + theName + "'";
request.onreadystatechange = createStateChangeCallback(request);
request.open("GET", url, true);
request.setRequestHeader("Content-Type", "application/json");
request.send();
}
}

request.send(values);
This won't work with a "GET". Try
request.open("POST", url, true);
http://www.w3schools.com/ajax/ajax_xmlhttprequest_send.asp

You need to:
decide whether you want GET or POST. For GET request you need all parameters to be in Url (and body to be empty), for POST you can use both. As of current code you are expecting GET, but sending POST.
properly add query parameter - name and encoded value. encodeUriComponent is JavaScript function of choice, see Build URL from Form Fields with Javascript or jquery for details
if using POST you need to properly encode parameters there too as well specify correct "content-type" header.
if sending JSON you need to decode JSON server side.
Alternatively you can use hidden form to perform POST/GET as covered in JavaScript post request like a form submit
Side note: jQuery.ajax does most of that for you and good source to look through if you want to do all yourself.

Like Alan said, use the POST method. Or pass your arguments in your URL before opening it, e.g.
var url = "Default.aspx/CheckName?userName=" + values;
EDIT : no, it's probably a bad idea since you want to send JSON, forget what I said.

If you need to go for POST, then you need to send it like this.
var values = JSON.stringify({"'userName':'"+ userName+ "'"});
And you have to change HttpGet to HttpPost

Given that your server side method asks for GET, you need:
request.open("GET", url + "?username=" + userName, true);
request.send();
The works for me:
function checkUserName() {
var request = new XMLHttpRequest();
if (request == null) {
alert("Unable to create request.");
} else {
var userName = "Shaun Luttin";
var url = '#Url.RouteUrl(new{ action="CheckName", controller="Home"})';
request.onreadystatechange = function() {
if (request.readyState == XMLHttpRequest.DONE ) {
if(request.status == 200){
document.getElementById("myDiv").innerHTML = request.responseText;
}
else if(request.status == 400) {
alert('There was an error 400')
}
else {
alert('something else other than 200 was returned')
}
}
}
request.open("GET", url + "?username=" + userName, true);
request.send();
}
}
With this on the server side:
[HttpGet]
public string CheckName(string userName)
{
return userName + " modified backstage";
}

Force "charset=x-user-defined'" on jQuery Ajax Post

I am trying to call a Hessian web service from a Javascript application, but I'm having issues parsing the response, since jQuery is treating the response as text and stripping the first bytes of it.
In my research, I have found out that you need to set the charset as 'charset=x-user-defined' in order to the browser leave my bytes as is. But, according the ajax docs:
Sending Data to the Server
By default, Ajax requests are sent using the GET HTTP method. If the
POST method is required, the method can be specified by setting a
value for the type option. This option affects how the contents of the
data option are sent to the server. POST data will always be
transmitted to the server using UTF-8 charset, per the W3C
XMLHTTPRequest standard.
And indeed, the charset is not changing regardless of the settings I used. I have tried the following, separately and all at once, with no luck
$.ajax({
type : 'POST',
url : url,
timeout : 3000,
data : parameters,
contentType : "x-application/hessian; charset=x-user-defined'",
mimeType: 'text/plain; charset=x-user-defined',
headers: {
Accept : "text/plain; charset=x-user-defined",
"Content-Type": "text/plain; charset=x-user-defined"
},
beforeSend : function(xhr) {
xhr.overrideMimeType("text/plain; charset=x-user-defined");
}
})
Also I tried to mess around with the data converters and custom contenttypes defined in jQuery, with no succes.
It appears that as per the standard, I will not be able to do this. It works with GET but not with POST, and the Hessian protocol requires POST.
Do you have any ideas? Or do I need to start to build my XHR method form scratch?

Turns out that I was making a silly mistake somewhere else. But anyhow, I found a sweet way for handling binary data on request and responses, from here.
define(function() {
// Do setup work here
function configurationException(message) {
throw new Error(message + " missing from configuration object");
}
return {
post : function(config) {
if (config) {
var url = config.url || configurationException("url");
var done = config.done || configurationException("callback function");
var timeout = config.timeout || 10000;
var data;
if (config.data) {
data = config.data;
} else {
data = null;
console.warn('No data is specified in binaryPost');
}
var request = new XMLHttpRequest();
request.open("POST", url, true);
request.responseType = "arraybuffer";
request.setRequestHeader("Content-Type", "x-application/hessian;");
request.onload = function(oEvent) {
var arrayBuffer = request.response; // Note: not oReq.responseText
if (arrayBuffer) {
var byteArray = new Uint8Array(arrayBuffer);
done(byteArray);
}
};
request.send(data);
} else {
throw new Error("Configuration object is missing");
}
}
};
});
Hope you find it useful