How do I use an API to query data from a dataset?

I would like to upload a small dataset, and then use a Mockaroo API to return this dataset based on where clauses through the URL.

Consider this example, here is the URL:

/project/user_code/:username.json

Where :username is a username found in a static dataset inserted into Mockaroo. The API is based off a schema, that is strictly routed, 1:1 to this dataset.

So you come to this URL, pass the username, which goes to the API, which goes to the schema, which goes to the dataset, and returns a row, or rows where the column = the parameter :username.

How would I do this in the script API?