Getting a Request.Headers Value

How to know if an HTTP request header value exists

if (Request.Headers["XYZComponent"].Count() > 0)

... will attempted to count the number of characters in the returned string, but if the header doesn't exist it will return NULL, hence why it's throwing an exception. Your second example effectively does the same thing, it will search through the collection of Headers and return NULL if it doesn't exist, which you then attempt to count the number of characters on:

Use this instead:

if(Request.Headers["XYZComponent"] != null)

Or if you want to treat blank or empty strings as not set then use:

if((Request.Headers["XYZComponent"] ?? "").Trim().Length > 0)

The Null Coalesce operator ?? will return a blank string if the header is null, stopping it throwing a NullReferenceException.

A variation of your second attempt will also work:

if (Request.Headers.AllKeys.Any(k => string.Equals(k, "XYZComponent")))

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Edit: Sorry didn't realise you were explicitly checking for the value true:

bool isSet = Boolean.TryParse(Request.Headers["XYZComponent"], out isSet) && isSet;

Will return false if Header value is false, or if Header has not been set or if Header is any other value other than true or false. Will return true is the Header value is the string 'true'

How to extract custom header value in Web API message handler?

Try something like this:

IEnumerable<string> headerValues = request.Headers.GetValues("MyCustomID");
var id = headerValues.FirstOrDefault();

There's also a TryGetValues method on Headers you can use if you're not always guaranteed to have access to the header.

How to read the php request header values?

From your screenshot (which appears to be from a browser's Network tool) it looks like you are talking about reading the header values which were received by the PHP script from the request your browser sent to PHP. That's nothing to do with cURL - cURL is for sending HTTP requests from your PHP script to another URL...it's unrelated to the interaction between the client-side and PHP via your webserver.

To read the headers which are incoming into your PHP script from the browser (or other client) making the request, you can use getallheaders() which returns an associative array of all the received headers.

e.g. to simply list them all:

foreach (getallheaders() as $name => $value) {
    echo "$name: $value\n";
}

Documentation: https://www.php.net/manual/en/function.getallheaders.php

How to get header values in https calls in c#

To retrieve data from your Header You can use this Request.Headers, you will find an example below

var apiKey = Request.Headers.GetValues("apiKey")

Resquest From Postman

Retrieve your data from header

How to get the header values in a GET request?

You can use Headers property of HttpRequest
Ref

resp.Headers

to get the headers for the response.

Get header value from http response in Typescript

Assuming that the function Intercept is in some service file, such as some.service.ts, in the component file, some.component.ts, I would try the following:

const xWebFrontednVersion: string;
this.someService.intercept(req, next).toPromise().then(response => {
        this.xWebFrontednVersion = response.headers.get('x-web-frontend-version');
})

How to get header request value in my laravel app on production?

Replace the API_ACCESS_KEY in your request with Api-Access-Key , also update it at your middleware too ,

as the underscores are invalid characters for header names,

Translation of headers to environment variables is more strict than
 before to mitigate some possible cross-site-scripting attacks via header injection.
 Header names containing invalid characters (including underscores) are
 no longer converted to environment variables.

for more info please check apache new features

Get request header value on cypress

Resolved with xhr.request.headers['token']

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