HTTP helpers in $util.http - AWS AppSync

HTTP helpers in $util.http

Note

We now primarily support the APPSYNC_JS runtime and its documentation. Please consider using the APPSYNC_JS runtime and its guides here.

The $util.http utility provides helper methods that you can use to manage HTTP request parameters and to add response headers.

$util.http.copyHeaders(Map) : Map

Copies the header from the map without the restricted set of HTTP headers. You can use this to forward request headers to your downstream HTTP endpoint.

{
    ...
    "params": {
        ...
        "headers": $util.http.copyHeaders($ctx.request.headers),
        ...
    },
    ...
}
$util.http.addResponseHeader(String, Object)

Adds a single custom header with the name (String) and value (Object) of the response. The following limitations apply:

  • Header names can't match any of the existing or restricted AWS or AWS AppSync headers.

  • Header names can't start with restricted prefixes, such as x-amzn- or x-amz-.

  • The size of custom response headers can't exceed 4 KB. This includes header names and values.

  • You should define each response header once per GraphQL operation. However, if you define a custom header with the same name multiple times, the most recent definition appears in the response. All headers count towards the header size limit regardless of naming.

...
$util.http.addResponseHeader("itemsCount", 7)
$util.http.addResponseHeader("render", $ctx.args.render)
...
$util.http.addResponseHeaders(Map)

Adds multiple response headers to the response from the specified map of names (String) and values (Object). The same limitations listed for the addResponseHeader(String, Object) method also apply to this method.

...
#set($headersMap = {})
$util.qr($headersMap.put("headerInt", 12))
$util.qr($headersMap.put("headerString", "stringValue"))
$util.qr($headersMap.put("headerObject", {"field1": 7, "field2": "string"}))
$util.http.addResponseHeaders($headersMap)
...