Templating

Before we begin

Templating is where Mocko really shines, it allows you to create dynamic mocks and simulate complicated scenarios with ease. You can use templating in any installation of Mocko, either standalone mode, complete stack or hybrid.

To use templating you must have a working installation of Mocko, either locally or in a server or cluster. If you don't, don't worry, it'll take you just a few minutes to get started by clicking here.

In our examples we'll show only the templates, in your standalone installation, they go in the body parameter of the mock stanza. In your complete stack, they go in the Body text field in the mock creation context (full-screen dialog).

Handlebars

When defining your body template, you can use Handlebars, a minimal templating language. In a GET /cats/{name} mock, the following body template:

{
    "id": 1,
    "name": "{{ request.params.name }}"
}

Would produce a response like this in a GET /cats/george:

{
    "id": 1,
    "name": "george"
}

Other than that, you can use helpers from the handlebars-helpers repository. Here's an example:

{
    "id": 1,
    "name": "{{capitalizeAll request.params.name }}"
}

Producing on GET /cats/george:

{
    "id": 1,
    "name": "George"
}

Context

You can access several fields from the request from your template:

• request.params: Params you defined in the URL
• request.headers: Request headers
• request.query: Query parameters (the part after ? in the URL)
• request.body: Fields from the request body, when sent as JSON

Here's an example using some of them, PUT /cats/{id}:

{
    "id": {{ request.params.id }},
    "name": "{{ request.body.name }}",
    "key": "{{ request.headers.x-key }}"
}

Blocks

You can use block helpers to perform conditionals or loops in your template, here is an example on GET /cats/{name}:

{{#startsWith 'g' (downcase request.params.name) }}
    {
        "id": 1,
        "name": "{{capitalizeAll request.params.name }}"
    }
{{else}}
    {{! You can set the status conditionally from here with the 'setStatus' helper }}
    {{setStatus 404}}
    {
        "error": "Not found error",
        "message": "Cat not found"
    }
{{/startsWith}}

You can open block helpers with a # before its name and close with a / before it. Also, block helpers can have else blocks like in the example above.

You might have noticed that we used the downcase helper inside the startsWith helper, that is totally possible and you can nest as many of them as you want. You call nested helpers with parenthesis (( and )).

You can add comments to your templates with ! like in the example above.

As you might have noticed, we used a special Mocko helper setStatus to change the status dynamically. In the example above, the status will be changed to 404 when the condition is false and the else block is called.

Tips and tricks

Logging

You can log anything to Mocko's console with the log helper, here are some examples:

POST /cats

{{log 'Received a request to create a cat named ' request.body.name ' of age ' request.body.age }}
{
    "id": {{random 1 100}}
}

GET /cats/{id}

{{#is request.params.id '1'}}
    {
        "id": 1,
        "name": "George"
    }
{{else is request.params.id '2'}}
    {
        "id": 2,
        "name": "Alice"
    }
{{else}}
    {{log 'Trying to fetch unknown cat with id ' request.params.id }}
    {{setStatus 404}}
    {
        "error": "Not found error",
        "message": "Cat not found"
    }
{{/is}}

You can also log the parameters you are receiving to make it easier to develop the templates:

{{log (JSONstringify request)}}

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