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Response Processors

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A special filter, mainly used to inject page contributions.

Response processors are only available in component rendering, not via mappings.

Introduction

Processors get executed between the component rendering step, and the contributions filter in the site service pipeline. Response processors are commonly used by apps that need to inject page contributions without placing a component on the page.

Use cases are:

  • Dynamically adding page contributions (i.e. script tags)

  • General manipulation of the response markup i.e. headers or body (i.e. adding SEO tags).

Consider using regular HTTP Filters for other use-cases.

Usage

Create a response processor by placing an implementation under src/main/resources/cms/processors/, for example cms/processors/tracker.ts.

The implementation must export a responseProcessor function. It receives a request and a response object. The example below dynamically adds a bodyEnd page contribution to the response.

cms/processors/tracker.ts
exports.responseProcessor = (req, res) => {
    const trackingScript = '<script src="http://some.cdn/js/tracker.js"></script>';

    if (!res.pageContributions.bodyEnd) {
        res.pageContributions.bodyEnd = [];
    }
    res.pageContributions.bodyEnd.push(trackingScript);

    return res;
};

Triggering

To wire a processor into the execution pipeline, declare it in the app’s site descriptor, and add the application to the site.

cms/site.yaml
kind: "Site"
processors:
- name: "tracker" (1)
  order: 10       (2)
1 name is the filename of the processor (without extension).
2 order sets execution order; lower runs first.

Response processors may change any of the values of the response object, including: HTTP status code, response body, HTTP headers, cookies and page contributions. It is also possible to return the response object received without any changes.

Execution order

An application may contain multiple processors. Multiple applications can be added to a Site. When a page is rendered, all processors are ordered and executed accordingly.

The order of execution is determined by the order value (as defined in the site descriptor) combined with the order of the application list within the site.

Processors with a lower order will be executed first (across all apps within the site).

In case there are several filters with the same order number, the position of the applications (as configured on the site) determines the order of execution.

If applyFilters is set to false in the response object, any further response processing or filters will be ignored. Default value is true.

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