金字塔：从列表生成 json 视图

Question

How to generate json views from a list of strings with Pyramid?

With the following attempt only the view of the last element of the list is generated; jkl_json in this case, the others produce 404 Not Found .

names = ['abc', 'def', 'ghi', 'jkl']
for nm in names:
    @view_config(route_name='{}_json'.format(nm),
                 renderer='json',)
    def names_json(request):
        nm_cls = globals()[nm.title()]
        ...

This does actually work with html views; but not with json views.

Answer 1

I would suggest using the Configurator.add_view method to add views programmatically:

def json_view(request):
    ...

names = ['abc', 'def', 'ghi', 'jkl']
for nm in names:
    config.add_view(json_view, route_name='{}_json'.format(nm),
                 renderer='json',)

Your approach with decorators in a loop is unlikely to work even with html I think...

Answer 2

This happens because Pyramid uses the Venusian library for decorators; they attach information to functions instead of registering the view instantly. This information is later processed by config.scan , and only then is the route actually registered. In your code you're replacing the names_json function with another function by the same name on each loop. Since only last of them is visible in the module, with only the last view_config data attached to it, this is what Venusian picks up when scanning.

---

You should instead apply the decorators to exactly one function. If you remember that

 @view_config(route_name='foo')
 def bar(request):
     return Response()

is just syntactic sugar for

 def bar(request):
     return Response()

 bar = view_config(route_name='foo')

you can do

def names_json(request):
    ...

names = ['abc', 'def', 'ghi', 'jkl']
for nm in names:
    names_json = view_config(route_name='{}_json'.format(nm),
             renderer='json')(names_json)

---

On the other hand, if the paths are like this, perhaps you can just use a single route for all of them:

config.add_route('names', '/foo/{name:abc|def|ghi|jkl}.json')

where the route would match any of /foo/abc.json , /foo/def.json , /foo/ghi.json or /foo/jkl.json , and the name would be available as request.matchdict['name'] within the view.