Basically, you can wrap multiple parameters in a single class and use this class as a parameter to your Web API controller method. Here is the updated Web API controller method. A DOMString, without the question mark. (Returns an empty string if no search parameters have been set.) Examples. Controls how the next row will be returned to the caller. This value must be one of the PDO::FETCH. constants, defaulting to value of PDO::ATTRDEFAULTFETCHMODE (which defaults to PDO::FETCHBOTH). PDO::FETCHASSOC: returns an array indexed by column name as returned in your result set. Notes Some default values for the init parameter changed in Samsung Internet 5.0. See the Properties section for details. See the Properties section for details. Cross-origin referrer stripped out and navigate mode converted to same-origin when constructor created from existing Request object.
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We all remember the dreaded XMLHttpRequest we used back in the day to make requests, it involved some really messy code, it didn't give us promises and let's just be honest, it wasn't pretty JavaScript, right? Maybe if you were using jQuery, you used the cleaner syntax with jQuery.ajax().
Well JavaScript has it's own built-in clean way now. Along comes the Fetch API a new standard to make server request jam-packed with promises and all those things we learned to love over the years.
How do we use the Fetch API?
Groups pro 4 16. In a very simple manner all you really do is call fetch with the URL you want, by default the Fetch API uses the GET method, so a very simple call would be like this:
Looks pretty simple right? So let's starting using it…
We are now going to build a simple GET request, in this case, I will use the Random User API and we will get 10 users and show them on the page using vanilla JavaScript.
Let's get started with the HTML, all we really need is a heading and an unordered list:
The idea is to get all the data from the Random User API and display it in list items inside the author's list.
The first step is to actually set the URL we need and also the list we are gonna put the data in, so in the Javascript we write:
I have set these to consts so you don't risk changing these in the future and these two are meant to be constants through all the project.
Now we get into actual Fetch API:
Let's review this code, shall we?
So first we are calling the Fetch API and passing it the URL we defined as a constant above and since no more parameters are set this is a simple GET request.
Then we get a response but the response we get is not JSON but an object with a series of methods we can use depending on what we want to do with the information, these methods include:
- clone() - As the method implies this method creates a clone of the response.
- redirect() - This method creates a new response but with a different URL.
- arrayBuffer() - In here we return a promise that resolves with an ArrayBuffer.
- formData() - Also returns a promise but one that resolves with FormData object.
- blob() - This is one resolves with a Blob.
- text() - In this case it resolves with a string.
- json() - Lastly we have the method to that resolves the promise with JSON.
Looking at all these methods the one we want is the JSON one because we want to handle our data as a JSON object so we add:
Now let's get to the part we create the list items, for that, I created two helper functions at the top of my file just to make the code simpler down the line:
All these functions do is append and create elements as you can see.
Once this is done we can move on to the resolution of our promise and add the code we need to append these list items to our unordered list:
So first we define authors as the response we get from the request then we map over all the authors and for each we create a list item, a span, and an image.
In the image source, we place the picture of the user, the HTML of the span will be the first and last name interpolated and then all we need to do is append this to their rightful parents and voilá, our HTTP request in vanilla JavaScript is done and returning something to the HTML.
To handle our catch all I will do is console log the error as we get it but you can do whatever you want with the error such as append it to the HTML with the functions we created. This is the full code of our little request:
Handling more requests like POST
So this is a GET request, the default one for the fetch function but of course we can do all other types of requests and also change the headers and off course send data, all we need for this is to set our object and pass it as the second argument of the fetch function:
Vue Fetch Get Params
You can also define cache, mode and all those things you are used to defining in your POST requests.
To create our object and use the fetch function we also have another option and that is to use the request constructor to create our request object, so instead of defining the object in the function itself we do this:
You can use the way you are most comfortable with to build your request object.
While the Fetch API is not yet supported by all the browsers (currently Safari does not support it) it is the beautiful replacement for XMLHttpRequest we desperately needed in our life.
There are also polyfills if you really want to use it in more professional projects.
The cmi5 specification calls for a 'fetch' parameter to be added to the launch URL when opening and Assignable Unit (AU). What is the cmi5 fetch parameter? How is it used? Are there any 'gotchas'? In this article I will attempt to end the confusion.
Author's Note: This is a technical article aimed at content tool developers, or those that are creating cmi5 AU by hand.
What is the fetch Parameter?
The cmi5 fetch parameter is a URL that must be called by the AU. The fetch URL must be used by the AU to get an authorization token. This token is then placed in the Authorization header for all HTTP requests made to the xAPI endpoint. In other words, an AU's authorization to write to the Learning Record Store (LRS) is via the token retrieved from the fetch URL.
The fetch Parameter Rules
There just a few rules around the fetch parameter:
Js Fetch Get Params
- The AU may call the URL only ONCE per session. Subsequent calls to the URL by the AU will receive an error.
- The rule above indicates the LMS must generate a unique fetch URL for each launch of an AU.
The Gotcha
There is an obvious 'gotcha' in rule number 1 above. What if the user refreshes their browser in the middle of an AU? If the content is unprepared for this event, it will attempt to call the fetch URL again, get an error and likely display that error to the user. At this point the user is basically dead in the water because the AU has lost authorization to write to the LRS.
There is a simple solution for this and it is called 'sessionStorage.' All major browsers support the ability to store data locally with the sessionStorage object. Here is a simple script, using jquery, to first check if the required token exists in sessionStorage, and if not then go ahead and get it from the fetch URL (Warning, code ahead).
$(function() { // First, Read the fetch url parameters var fetchUrl = parse('fetch');
// Next, check if this value exists in sessionStorage. var token = sessionStorage.getItem(fetchUrl); Shareurl v1 1.
// Was the token found in sessionStorage? if (!token) { // Call the fetch url to get the token $.post(fetchUrl, null, function(t) { token = t['auth-token'];
// Save the token to sessionStorage sessionStorage.setItem(fetchUrl, token);
}, 'json'); }});
Fetch Get Params Json
Why does this work? The fetch parameter is passed on AU launch URL. If the browser is refreshed, the fetch parameter is unchanged. So we use the fetch URL as the 'name' property in our call to sessionStorage.setItem(). Then, if the browser is refreshed we can easily find the previously obtained authorization token with a call to sessionStorage.getItem().
For more information on cmi5, be sure and check out this blog's xAPI and cmi5 category.
Fetch Query Param
