Web.Headers

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Web.Headers is a Power Query M function that retrieves headers from a URL with the option to include additional properties through optional parameters. The function returns the downloaded headers as a record with a subset of response headers available for security reasons.

Compatible with: Power BI Service Power BI Desktop Excel Microsoft 365

Syntax

Web.Headers(
   url as text,
   optional options as nullable record,
) as record

Description

Returns the headers downloaded from url as a record. An optional record parameter, options, may be provided to specify additional properties. The record can contain the following fields:

  • Query : Programmatically add query parameters to the URL without having to worry about escaping.
  • ApiKeyName : If the target site has a notion of an API key, this parameter can be used to specify the name (not the value) of the key parameter that must be used in the URL. The actual key value is provided in the credential.
  • Headers : Specifying this value as a record will supply additional headers to an HTTP request.
  • Timeout : Specifying this value as a duration will change the timeout for an HTTP request. The default value is 100 seconds.
  • ExcludedFromCacheKey : Specifying this value as a list will exclude these HTTP header keys from being part of the calculation for caching data.
  • IsRetry : Specifying this logical value as true will ignore any existing response in the cache when fetching data.
  • ManualStatusHandling : Specifying this value as a list will prevent any builtin handling for HTTP requests whose response has one of these status codes.
  • RelativePath : Specifying this value as text appends it to the base URL before making the request.
The HTTP request is made with the HEAD method. Outside of a custom data connector context, only a subset of response headers is available (for security reasons).

Examples

Retrieve the HTTP headers for "https://bing.com/search?q=Power+Query" using the RelativePath and Query options.

let
    searchText = "Power Query"
in
    Web.Headers( 
        "https://www.bing.com",
        [
            RelativePath = "search",
            Query = [q = searchText]
        ]
     )

 /* Output: 
( [
    #"Cache-Control" = "private, max-age=0",
    #"Content-Encoding" = "gzip",
    #"Content-Length" = "0",
    #"Content-Type" = "text/html; charset=utf-8",
    Date = "Tue, 14 Dec 2021 16:57:25 GMT",
    Expires = "Tue, 14 Dec 2021 16:56:25 GMT",
    Vary = "Accept-Encoding"
]
meta [
    Response.Status = 200
] )
 */ 

Other functions related to Web.Headers are:

Contribute » | Contributors: Rick de Groot
Microsoft documentation: https://learn.microsoft.com/en-us/powerquery-m/web-headers