In my project I have javascript iterating through a set of radio buttons. First it checks to see if the selected button in the nameset has been changed, then if it has been, it records the value of the newly selected button for that row, appending it to a variable dataString, before moving on to the next buttonset. This is all well and good, it collects all the data perfectly. I run into issues when I try to send that data through AJAX, however.
For each row that is changed, I append a rowName variable and a deviceName variable do dataString. Ideally I want to send these such that when I get the data to Python, I end up with a rowName list and a deviceName list, as happens when you send multiple variables of the same name.
My AJAX call is as follows:
var call= $.ajax({
type: "POST",
url: "http://localhost/cgi-bin/savestate.py",
data: dataString
}).done(function() {
document.getElementById("upper").innerHTML+=(call.responseText);
});
As I said, the data I need to send gets collected well enough. Right now, dataString is formatted so that it looks like this:
"{rowName: 'firstRowName', deviceName: 'firstDeviceName', rowName: 'secondRowName', deviceName: 'secondDeviceName'}"
I have also tried changing the AJAX call so that the data: call looks like:
data: {dataString}
And formatted dataString to look like:
"rowName: 'firstRowName', deviceName: 'firstDeviceName', rowName: 'secondRowName', deviceName: 'secondDeviceName'"
Either way I try to send it, the data does not get to the python script. When I return the data from Python, it comes out as
FieldStorage(None, None, [])
Now since the format of the data: attribute in the AJAX call is {keyname: value, etc}, is it possible to send the data in a premade list in that format, or do I have to change the way I've formatted dataString and send it some other way?
I ended up achieving the desired effect two ways.
First Method: Thinking back to how I performed AJAX requests prior to implementing JQuery, I formatted dataString to
rowName=firstRowName&deviceName=firstDeviceName&rowName=secondRowName&deviceName=secondDeviceName
and so on. Then I simply appended that to my url in the AJAX call, so that it looked like:
url:"http://localhost/cgi-bin/saveState.py"+dataString
Second Method: The other way that I got it to work was to format the dataString the same way as in the First Method, but then simply use that as my data attribute.
data: dataString
I found it strange that this worked, since it doesn't at all follow the usual format for the data: call. But alas, it did indeed work.
In your initial attempt, you are sending POST data to your Ajax method in JSON format. However, FieldStorage is expecting it in form format (application/x-www-form-urlencoded). The two methods you mention in your answer give it to the Ajax method in form format.
Besides your solutions, another approach is to use a JSON parsing library instead of FieldStorage. Exactly how you do this depends on the framework you are using - is it Django, Pyramid, etc?
Related
I have an ajax call to a PHP module which returns some HTML. I want to examine this HTML and extract the data from some custom attributes before considering whether to upload the HTML into the DOM.
I can see the data from the network activity as well as via console.log. I want to extract the values for the data-pk attribute and test them before deciding whether to upload the HTML or just bypass it.
$.ajax({
url: "./modules/get_recent.php",
method: "POST",
data: {chat_id:chat_id, chat_name:chat_name, host_id:host_id, host_name:host_name}, // received as a $_POST array
success: function(data)
{
console.log(data);
},
})
and some of the console log data are:
class="the_pks" data-pk="11"
class="the_pks" data-pk="10"
etc.
In the above data I want to extract and 'have a look at' the numbers 11 and 10.
I just do not know how to extract these data-pk values from the returned data from the ajax call. Doing an each on class 'the_pks' does not work as at the time I am looking at the data they have not been loaded into the DOM.
I have searched SO for this but have not come up with an answer.
Any advice will be most appreciated.
I hope I understand your question.
If you get a HTML as a response, you can always create an element and insert that html inside it, without adding it to the DOM. And after that you can search it as you do with a DOM element.
const node = document.createElement("div");
//then you can do
node.appendChild(data);
// or
node.innerHTML = data;
And after that you can search inside the node:
node.querySelectorAll("[data-pk]")
I will re-engineer this - it was probably a clumsy way to try and achieve what I wanted anyway. Thanks to those who tried to help.
I am on Linux -both browser side & server side- with a recent Firefox 38 or 42 if that matters; this question gives more context, and the github GPLv3 project containing my code. It is not a usual Web application (it would have usually one, and perhaps a dozen, of simultaneous Web users). I am writing or generating both server & browser side code
Let's suppose I have some HTML5 code like
<div id="mydyndiv_id"></div>
I am making an AJAX request with JQuery. On success it should insert some (AJAX generated) HTML element, e.g. <b>bold</b> (in reality it is a much bigger HTML fragment with nested <span>-s whose content is dynamically generated from the POST argument of the AJAX request), into that div and call some other Javascript function doit, e.g. doit(42) only once just after the AJAX request (e.g. that function would clear some other <textarea> in my page, and the 42 argument is provided by the AJAX response). I can change code both on server side (e.g. alter the AJAX processing) and on browser side.
What is the most idiomatic way to achieve that?
making a JSON AJAX which contains both the inserted HTML & the function argument, so the AJAX response could be {"text":"<b>bold</b>", "data": 42}" of Content-type: "application/json" and the Javascript code would be
$.ajax
({url: "/someajax",
method: "POST",
data: {"somearg": "foo"},
datatype: "json",
success: function(jsa) {
$("#mydyndiv_id").html(jsa.text);
doit(jsa.data);
}});
this is rather heavy, the server should double-encode HTML&JSON the HTML fragment: it needs first to construct the <b>bold</b> fragment -with HTML encoding, and then to construct the JSON object and send it.
making an HTML AJAX which has some <script> element. The AJAX response would be of Content-type: text/html and would contain <b>bold</b><script>doit(42)</script>, and the Javascript code would be
$.ajax
({url: "/someajax",
method: "POST",
data: {"somearg": "foo"},
datatype: "html",
success: function(ht) {
$("#mydyndiv_id").html(ht);
}});
this might be wrong, since the doit(42) function could be perhaps called more than once and is kept in the DOM and I don't want that
making a Javascript AJAX; the AJAX response would be of Content-type: application-javascript and would contain:
$("#mydyndiv_id").html("<b>bold</b>");
doit(42);
with the AJAX invocation in Javascript being
$.ajax
({url: "/someajax",
method: "POST",
data: {"somearg": "foo"},
datatype: "script",
success: function(jscode) { /* empty body */ }
})
This is brittle w.r.t. errors in doit(42) (see this question; the only debugging technique I found is lots of console.log and that is painful) and also requires double encoding on server side.
Of course, any other technique is welcome!
PS. If you are curious, the code is commit a6f1dd7514e5 of the MELT monitor (alpha stage) and you would try the http://localhost.localdomain:8086/nanoedit.html URL in your browser; this software (which is also a specialized HTTP server!) would have only very few simultaneous Web users (usually one, perhaps a dozen); in that sense it is not a usual web application. In my dreams it could become a workbench for a small team of (C & C++) software developers, and the GUI of that workbench would be their browser.
These different approaches have pros and cons, but generally the first two options are more advisable, let's see:
JSON AJAX
First of all, working with templating on your server is the right approach. If you use this method you will be able to pass more flexible data from your server to your client as you can e.g. use {"text":"<b>bold</b>", "data": 42, "more_data": 43}".
You are not bound to use just the data at the moment you initially create the service but expand passed data easily.
HTML AJAX
This method is simple and if you would like to have a service for every single piece of data you need to pass, rather than a service for multiple pieces, this is the preferable choice. In difference to the JSON AJAX method, you will not be able to expand here and if needed, you'll naturally have to create a new service for passing new data.
Javascript AJAX
Altough it is possible, tis method is rather unadivsable, as you can not maintain your application in a reasonable way, as your templating is client-side. See what Peter-Paul Koch says here:
Although templating is the correct solution, doing it in the browser is fundamentally wrong. The cost of application maintenance should not be offloaded onto all their users’s browsers (we’re talking millions of hits per month here) — especially not the mobile ones. This job belongs on the server.
Further reading : Why client-side templating is wrong.
First approach looks good for me, but generally it's a little bit ugly to transfer raw HTML via AJAX, if you have to transfer raw HTML it's better to use techniques called PJAX, see jquery-pjax plugin for more information of how to use and customize it.
From my point of view best approach would start using jquery-template to avoid transferring HTML over AJAX and start transfer only object witch would be rendered to template on frontend.Call doit method within handling success is ok until it use data provided in response.
I would rather go with a variation of first approach. But, it depends on the kind of generated HTML that you are currently returning from the server-side.
If it is a simple element, then you could just return a JSON object from server with one of the properties identifying the element.
For example, the response from the web-service would be like:
{'elem': 'b', 'text': 'bold', 'value': '42'}
And you consume that in the AJAX call like this:
$.ajax({
datatype: "json",
...
success: function(response) {
// create the required element client-side
var elem = document.createElement(response.elem);
// use other properties of the response object
elem.textContent = response.text + doit(response.value);
// add the element to your div
$('#mydiv-1')[0].appendChild(elem);
}
});
Where doit is the Javascript function that is already part of your client-side code-base and you just use the arguments returned by the web-service.
Alternatively, if your generated HTML is a complex fragment, then you need to identify common patterns and use client-side templates to transform the returned data into presentation.
For example, your client-side template may look like this:
<script type='text/template' id='tmpl'>
<div><h3></h3><p></p><h5></h5></div>
</script>
Your web-service returns something like this:
{'title': 'title', 'text': 'paragraph', 'value': '42'}
And you consume that in the AJAX call like this:
$.ajax({
datatype: "json",
...
success: function(response) {
// clone the client-side template
var template = $('#tmpl').html(), $elem = $(template);
// append to your div
$('#mydiv-2').append($elem);
// populate the cloned template with returned object properties
$elem.find('h3').text(response.title);
$elem.find('p').text(response.text);
$elem.find('h5').text(doit(response.value));
}
});
This way you avoid returning generated HTML from your server and manage the presentation details at the client-side only. Your web-service needs not to know the presentational aspects and deals only with raw data (consuming or spewing). The client-side code gets data from the web-service and deals with using and/or presenting that data as part of the client-side app.
Demo for both the variations: https://jsfiddle.net/abhitalks/wuhnuv99/
Bottom-line: Don't transfer code. Transfer data. Code should then use that data.
Here is a script.
It provides some select inputs which allow picking from various types of options. When the submit button is pressed it records the data in mats and pushes the mats array into an array called materialsUsed. Everytime the submit button is clicked a new array is added in materialsUsed.
I want to know how to send the materialsUsed array through a URL to php to extract the data there and insert it into an array created in PHP.
var mats = [name= "", thick= "", size= "", quantity= 0, price= 0];
mats.name = document.getElementById("mat").options[document.getElementById("mat").selectedIndex].value;
mats.thick = document.getElementById("thick").options[document.getElementById("thick").selectedIndex].value;
mats.size = document.getElementById("size").options[document.getElementById("size").selectedIndex].value;
mats.price = parseFloat($('#priceto').val()).toFixed(2);
mats.quantity = parseInt($('#quant').val());
materialsUsed.push(mats);
If you would like to simply load them as GET values into the URL just set them directly in the URL using location.href. Then simply use $__GET (IE: $__GET['mat']) in PHP to grab values.
var baseURL = "http://yourdomain.com";
window.location.href = baseURL + "?mat=" + mats.name + "&thick=" + mats.thick etc...
First you have to properly prepare your mats array and convert materialsUsed array into JSON format. Then you can call an ajax function like below, to send it to the php script.
var jsonString = JSON.stringify(materialsUsed);
$.ajax({
type: "GET",
url: "your_script.php",
data: {data : jsonString},
success: function(){
alert("Successfully sent the data!");
}
});
From the your_script.php file, you can perform this to extract the array.
$data = json_decode(stripslashes($_GET['data']));
Important
When using GET method, the amount of the data (length of url) is
limited. So, if your materialUsed array is too huge, you should use
POST method instead.
I think what you're looking for is making an ajax call to your php script providing your js array as its data.
You should listen for the form submission event in your javascript and launch an AJAX call to your PHP script providing your array. You may send your array via the URL (query string) using a GET or in the request body using a POST (that's an option you specify in your AJAX call). Then you would just retrieve your array in your php script an do whatever you want with it.
I suggest you read more on form submission events and AJAX calls in javaScript.
Quick hint : if you have the possibility to do so, try using jQuery as AJAX is way easier to use with jQuery.
You are trying to use associative array, but it's not possible in Javascript as far as I know.
I'd say the best way to do that is creating a object, parsing to json and sending to php. Does't look that hard.
What are some arguments as to when to use JSON external file such as with jQuery's
$.getJSON('external.json',function(data){});
(ajax retrieving) versus defining it in javascript with
var myJson = { "someVar": { "1": ["test1","test2"], "2": ["test3","test4"]} }
What is the "proper" way of doing it? Does it depend on JSON length or are there any other factors that can tell you what approach to use?
The way I see it: choose between loading another file which is supposed to be slow as you are loading data via ajax call or adding plenty of lines into already packed javascript file which is not a good thing either. Surely there must be some distinction as to where you should use one or another ... ?
I am not interested only in speed difference (getting file from ajax is of course slower) but also in other aspects such as what is generally used when and what should be used in some case ...
The first one is a shorthand for:
$.ajax({
dataType: "json",
url: url,
data: data,
success: success
});
This is an Ajax request which will take more time than having a simple JSON object into the file.
I would prefer the second one IF it's possible. Also if you attend to have good performances the first one is longer.
time( Loading+parsing 2 files ) >> time( Read a Javascript object )
If your data is known at page creation time you're probably best to use an object literal like:
var myJson = {...}
However, as Kursion mentions,
$.getJSON(...)
is a shorthand method for retrieving json data asynchronously via ajax. You'd use it if you want to retrieve data from the server that wasn't known at the time of page load...
For example, if a user enters a search term in an input control, you might want to retrieve JSON in response to that without performing a whole page update. You couldn't simply define a javascript object up-front because you wouldn't know what the search term was in advance.
I'm trying to create a note taking web app that will simply store notes client side using HTML5 local storage. I think JSON is the way to do it but unsure how to go about it.
I have a simple form set up with a Title and textarea. Is there a way I can submit the form and store the details entered with several "notes" then list them back?
I'm new to Javascript and JSON so any help would be appreciated.
there are many ways to use json.
1> u can create a funciton on HTML page and call ajax & post data.
here you have to use $("#txtboxid").val(). get value and post it.
2> use knock out js to bind two way.and call ajax.
here is simple code to call web app. using ajax call.
var params = { "clientID": $("#txtboxid") };
$.ajax({
type: "POST",
url: "http:localhost/Services/LogisticsAppSuite.svc/Json/GetAllLevelSubClients",
contentType: 'application/json',
data: JSON.stringify(params),
dataType: 'json',
async: false,
cache: false,
success: function (response) {
},
error: function (ErrorResponse) {
}
I have written a lib that works just like entity framework. I WILL put it here later, you can follow me there or contact me to get the source code now. Then you can write js code like:
var DemoDbContext = function(){ // define your db
nova.data.DbContext.call(this);
this.notes=new nova.data.Repository(...); // define your table
}
//todo: make DemoDbContext implement nova.data.DbContext
var Notes = function(){
this.id=0; this.name="";
}
//todo: make Note implement nova.data.Entity
How to query data?
var notes = new DemoDbContext().notes.toArray(function(data){});
How to add a note to db?
var db = new DemoDbContext();
db.notes.add(new Note(...));
db.saveChanges(callback);
Depending on the complexity of the information you want to store you may not need JSON.
You can use the setItem() method of localStorage in HTML5 to save a key/value pair on the client-side. You can only store string values with this method but if your notes don't have too complicated a structure, this would probably be the easiest way. Assuming this was some HTML you were using:
<input type="text" id="title"></input>
<textarea id="notes"></textarea>
You could use this simple Javascript code to store the information:
// on trigger (e.g. clicking a save button, or pressing a key)
localStorage.setItem('title', document.getElementById('title').value);
localStorage.setItem('textarea', document.getElementById('notes').value);
You would use localStorage.getItem() to retrieve the values.
Here is a simple JSFiddle I created to show you how the methods work (though not using the exact same code as above; this one relies on a keyup event).
The only reason you might want to use JSON, that I can see, is if you needed a structure with depth to your notes. For example you might want to attach notes with information like the date they were written and put them in a structure like this:
{
'title': {
'text':
'date':
}
'notes': {
'text':
'date':
}
}
That would be JSON. But bear in mind that the localStorage.setItem() method only accepts string values, you would need to turn the object into a string to do that and then convert it back when retrieving it with localStorage.getItem(). The methods JSON.stringify will do the object-to-string transformation and JSON.parse will do the reverse. But as I say this conversion means extra code and is only really worth it if your notes need to be that complicated.