web_poet.page_object decorator

web_poet/__init__.py

@@ -11,7 +11,7 @@
     HttpResponseBody,
 )
 from .overrides import PageObjectRegistry, consume_modules, OverrideRule
-
+from .functional import page_object
 
 default_registry = PageObjectRegistry()
 handle_urls = default_registry.handle_urls

web_poet/functional.py

@@ -0,0 +1,52 @@
+from typing import Callable, Type
+
+from web_poet.pages import ItemPage
+
+
+def page_object(func: Callable) -> Type[ItemPage]:
+    """
+    Decorator to create a Page Object from a function.
+    Note that the original function is destroyed, and
+    a class is created instead.
+
+    .. code-block:: python
+
+        @web_poet.page_object
+        def MyPage(resp: HttpResponse):
+            return {"title": resp.css("title::text").get()}
+
+    is a shortcut for
+
+    .. code-block:: python
+
+        class MyPage(web_poet.ItemPage):
+            def __init__(self, resp: HttpResponse):
+                self.resp = resp
+
+            def to_item(self):
+                return {"title": self.resp.css("title::text").get()}
+
+    """
+    class PageObject(ItemPage):
+        def __init__(self, *args, **kwargs):
+            # FIXME: save arguments as properly named attributes
+            # FIXME: __init__ method doesn't fail if parameters are wrong
+            self.args = args
+            self.kwargs = kwargs
+            super().__init__()
+
+        # TODO: async def support
+        def to_item(self):
+            return func(*self.args, **self.kwargs)
+
+    # FIXME: robustness, edge cases
+    PageObject.__module__ = func.__module__
+    PageObject.__name__ = func.__name__
+    PageObject.__qualname__ = func.__qualname__
+    PageObject.__doc__ = func.__doc__
+    PageObject.__init__.__annotations__ = func.__annotations__
+
+    # TODO: check that type annotations work properly
+    # TODO: preserve the original function as an attribute?
+    return PageObject
+