if

if Plugin

Control the execution of plugins with if conditionally. The SpEL expression language, Groovy, Jsonpath and XPath can be used to write the condition.

Running the Example

Note: You can test these requests using the provided HTTP request snippets.

1. Navigate to the examples/extending-membrane/if directory.
2. Start the Router by executing router-service.sh (Linux/Mac) or router-service.bat (Windows).
3. Execute the following requests (alternatively, use the requests.http file):

• JSON Request:

  curl -X POST http://localhost:2000 -H "Content-Type: application/json" -d '{"foo": "bar"}' -v

• JSON with 'name' Key as 'foo':

  curl -X POST http://localhost:2000 -H "Content-Type: application/json" -d '{"name": "foo"}' -v

• Query Parameter Check:

  curl -X GET 'http://localhost:2000/?param1=value1' -v

  curl -X GET 'http://localhost:2000/?param1=value2' -v

• Header Check for 'bar':

  curl -X GET http://localhost:2000 -H "X-Test-Header: foo" -v

  curl -X GET http://localhost:2000 -H "X-Test-Header: foobar" -v

• Large Body Detection:

  curl -X POST http://localhost:2000 -d "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum." -v

4. Review the Configuration:

• Take a look at proxies.xml to understand the configuration details and the conditional logic applied.

Response Manipulation

A common use case of the if plugin is the manipulation of responses based on the status code:

    <response>
        <if test="statusCode matches '[45]\d\d'">
            <template pretty="yes" contentType="application/json">
                {
                  "type": "https://membrane-api.io/error/",
                  "title": ${exc.response.statusMessage}
                }
            </template>
        </if>
        <if test="statusCode == 302" language="SpEL">
            <log message="Status code changed!"/>
            <groovy>exc.getResponse().setStatusCode(404)</groovy>
        </if>
    </response>

    <template>Success</template>
    <return statusCode="302"/>
</api>

if allows you to dynamically handle requests and adjust responses based on specified conditions.