Files, mocks, and injection

Local file rules let a page load a development bundle or fixed test fixture while everything else continues to come from the remote server.

Replace a response with a file

Use an absolute path:

Text
cdn.example.com/assets/app.js file:///Users/me/project/dist/app.jsapi.example.com/v1/user file:///Users/me/fixtures/user.json

On Windows, use a valid file URL that includes the drive letter. The PostGate process must have permission to read the target file.

mock provides another file-oriented mock action:

Text
api.example.com/v1/orders mock:///absolute/path/orders.json

Replace typed content

Use a body action when the value is short enough to remain readable:

Text
api.example.com/health json://{"ok":true,"source":"postgate"}example.com/banner htmlBody://<aside>Local environment</aside>

For reusable or multi-line payloads, save the content in Values and reference it rather than escaping it on one line.

Inject into a document

Text
example.com htmlAppend://<div id="local-badge">LOCAL</div>example.com jsAppend://console.info('PostGate active')example.com cssAppend://#local-badge{position:fixed;top:8px;right:8px}

Use htmlPrepend, jsPrepend, and cssPrepend to insert before existing content. htmlReplace, jsReplace, and cssReplace perform targeted replacement. Typed htmlBody, jsBody, and cssBody actions replace the corresponding body completely.

Injection is applied only to compatible response types. If an injection does not appear, check the response content-type and inspect the body preview in Capture.