Expressions allow you to get and transform existing data from:
- an environment,
- requests stored in a repository,
- the last response on/to the stored requests (if a response exists).

Note: Your request must have been sent before you add an expression inside.

You can put expressions in:
- URL,
- header names,
- header values,
- text body,
- form items values,
- assertions values.

There is no limit on how many expressions you can use in one declaration.
Expressions can be freely mixed with a plain text.

Use the expression builder

Restlet Client helps you build expressions with its expression builder. Whenever you can build an expression, a magic wand icon displays on the right of the field to launch the expression builder.

From the expression builder, you can select:
- Elements from your repository (projects, services, scenarios, etc.),
- Environment variables,
- Methods (Restlet Client displays only the relevant methods according to the environment).

expression builder

Note: The expression will be added where you placed your cursor before clicking the magic wand icon .

Ex 1: Build an expression to retrieve the id of the first element of the previous request you have launched


In this example, we are using a so called "petstore" API that references pets and users. Each pet has a status (pending, available or sold). What we want here is to find the first pet that is in pending status.


Launch a GET request to retrieve the pets with pending status.


expression builder

Launch another request to get the first pet of the list of pending pets by retrieving the id from the result of your first request with /pets/{petId}.

To do this, click at the end of the URL field and click the magic wand .

expression builder

You can now build your expression with the expression builder: select your API from the Repository elements and go as deep as necessary in your API.

expression builder

expression builder

Your expression displays at the bottom of the Expression builder pop-up as you are building it. Click Build.

{"Swagger Petstore"."/pet/findByStatus"."findPetsByStatus"."response"."body"."0"."id"}

Your expression now displays at the end of the URL. Click Send.

expression builder

Build expressions by hand

You can also build your expressions by hand in curly brackets.

Ex 2: an expression declarations




text${random()}other text${random()}

You can also use built-in methods to transform values.

Ex 3: calculate MD5 hash from text or JSON response body

${"Saved Request #1"."body".md5()}