Locust: Add support to modify request name (with dynamic parameters) through global handler

[devmonkey22]

Description of issue / feature request

Currently, https://docs.locust.io/en/latest/writing-a-locustfile.html#grouping-requests-to-urls-with-dynamic-parameters describes the approach to providing a custom request name to aggregate statistics by. This currently requires modifying each call to HttpSession.request or its helper methods, which is code I don't maintain. I can only pass in the locust session.

Alternatively, even though request_success and request_failure EventHooks allow watching the requests, it does not allow updating/setting the name.

Desired behavior

Support being able to modify the HttpSession.request function's request_meta attributes through the request_success and request_failure handlers.

For example, by being given the request_meta object, as well as the actual request/response object (so we can access url, etc), I can run a regular expression to replace IDs and GUIDs in the REST API URL with placeholders.

This way, the locust statistics will report the modified name/url aggregated, instead of one record per parameter value.

Environment settings (for bug reports)

• OS: Ubuntu 16
• Python version: 2.7
• Locust version: 0.8

Steps to reproduce (for bug reports)

N/A

Current Workaround

Currently, I am able to wrap the HttpSession.request function, so that I can modify the name parameter before passing it to the original function. This way I can use regular expressions to look for GUIDs and IDs and replace them with a placeholder.

This is based on an approach similar to https://stackoverflow.com/questions/258119/python-wrapping-method-invocations-with-pre-and-post-methods

[cgoldberg]

happy to review a PR if submitted

[ajt89]

Looking through the code, you should be able to get locust_request_meta from response if you pass in catch_response=True.

def route_b(self):
    response = self.client.get(
        '/b',
        name='route_b',
        catch_response=True,
    )

    if 'route_b' in response.text:
        response.locust_request_meta['name'] = 'new_name'
        response.success()
    else:
        response.failure('Got wrong response')

[cyberw]

@ajt89 Nice workaround. I think that should be good enough for most use cases.

[heyman]

I just want to add that I think wrapping the get/post/request method, as mentioned as a work-around in the OP, is a a perfectly fine practice. I've done something like this previously:

class MyBaseTaskSet(TaskSet):
    def get(self, *args, **kwargs):
        # customize each get-request here
        return self.client.get(*args, **kwargs)

and then make all TaskSets inherit from MyBaseTaskSet and use self.get() instead of self.client.get().