Fork of aspen.typecasting to clean some stuff up. Upstream it, ya?

gratipay.typecasting.cast(website, request, state)[source]

Implement typecasting (differently from stock Aspen).

When matching paths, Aspen looks for /%foo/ and then foo is a variable with the value in the URL path, so /bar/ would end up with foo='bar'.

There’s a dictionary at website.typecasters that maps variable names to functions, dependency-injectable as with website.algorithm (state-chain) functions. If an entry exists in typecasters for a given path variable, then the value of path[part] is replaced with the result of calling the function.

Before calling your cast function, we add an additional value to the state dict at path_part: the URL path part that matched, as a string. That is user input, so handle it carefully. It’s your job to raise Response(40x) if it’s bad input.