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Extracting response headers

Extracting response headers

When making requests using a CallRESTEndpointFNC , responses are returned along with the ResponseHeaders list in the form of:

[
   {
      "Name":"string",
      "Value":"string"
   }
]
Note:

The structure of the Header list when hosting and receiving requests is different, find out more here

Often, information is returned in these header values for subsequent use, values such as location are passed in headers for use in sub-sequent requests involving pagination.

CallRESTEndpoint: Response Headers:
  Transfer-Encoding = chunked
  Connection = keep-alive
  Access-Control-Allow-Origin = *
  Access-Control-Allow-Methods = GET
  Vary = User-Agent
  CF-Cache-Status = DYNAMIC
  cf-request-id = 06c048ffb00000077a8425d000000001
  Report-To = {"endpoints":[{"url":"https:\/\/a.nel.cloudflare.com\/report?s=8xScWvUIuL00gAIkoquwi%2Blpa5f6Up4XZjtkzO3kyGqv54RZC%2FtW7dzUZviJOnKsC6aM4Gq75bKrZieJxI5yUcG2xKwiLNIwZMYta0FY"}],"group":"cf-nel","max_age":604800}
  NEL = {"report_to":"cf-nel","max_age":604800}
  CF-RAY = 5fad777919b9077a-LHR
  Cache-Control = must-revalidate, no-cache
  Date = Tue, 01 Dec 2020 14:23:33 GMT
  Set-Cookie = __cfduid=d770f214e0e521e7d5e82a489e3f68d1b1606832613; expires=Thu, 31-Dec-20 14:23:33 GMT; path=/; domain=.icndb.com; HttpOnly; SameSite=Lax
  Server = cloudflare
  Content-Type = application/json
  Expires = Sat, 26 Jul 1997 05:00:00 GMT
  Content-Length = 167

Although you can see the full list of header values in the Debug Values panel like below:

image

In order to access header items within the list, there are 2 approaches:

  1. Use a ForEachFNC and loop through the CallRESTEndpoint.ResponseHeaders list.

    On each loop use an IfElseFNC to evaluate if the current loop value’s Name field matches your search term.
    image

    If it does, then use the value of ForEach.Loop.Value.

  2. Use the below expression to extract the needed value

    = CallRESTEndpoint.ResponseHeaders.Where(headerItem => headerItem.Name ==  "SearchTerm").FirstOrDefault().Value
    

    image

As you can see the second approach is much cleaner, although it requires an understanding of expressions.

Sample:

Take a look at the below sample Solution to give you a practical demonstration.

Solution (.lsoz) (6.2 KB)