ValueError: invalid literal for int() with base 10 trying to retrieve a query parameter from Google App engine

Question

I received the following error when trying to retrieve data using Google App Engine from a single entry to a single page e.g. foobar.com/page/1 would show all the data from id 1:

ValueError: invalid literal for int() with base 10

Here are the files:

Views.py

class One(webapp.RequestHandler):    
    def get(self, id):
        id         = models.Page.get_by_id(int(str(self.request.get("id")))) 
        page_query = models.Page.get(db.Key.from_path('Page', id))
        pages      = page_query

        template_values = {
            'pages': pages,
        }

        path = os.path.join(os.path.dirname(__file__), 'template/list.html')
        self.response.out.write(template.render(path, template_values))

Urls.py:

(r'/browse/(\d+)/', One),

Error:

Traceback (most recent call last):
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/__init__.py", line 501, in __call__
    handler.get(*groups)
  File "/Volumes/foobar/views.py", line 72, in get
    id = models.Page.get_by_id(int(str(self.request.get("id"))))
ValueError: invalid literal for int() with base 10: ''

Solution 1

I'm not quite sure what you're trying to achieve here. The first line:

    id         = models.Page.get_by_id(int(str(self.request.get("id")))) 

returns a Page object with an ID fetched from the query string. To make it work with the passed in argument, change it to:

    id         = models.Page.get_by_id(int(id)) 

Odder is the second line:

    page_query = models.Page.get(db.Key.from_path('Page', id))

This does not return a query - it returns a page object, and if you replace 'id' with 'int(id)' does precisely the same thing as the first line. What are you trying to achieve here?

Solution 2

Change self.request.get("id") to simply id, which is already being passed to your get handler.

The code, as you have it, would only work for URLs like /browse/1/?id=1

Comments

[gpjones]

Thanks for your help, now on the error. BadArgumentError: Expected an integer id or string name as argument 2; received <models.Page object at 0x7d65f70> (a Page).

[gpjones]

I'm trying to pull back a single entry onto the page. E.g. localhost:8080/browse/1/ - would display entry 1 localhost:8080/browse/2/ - would display entry 2 etc etc.. list.html contains: {% for page in pages %} {{ page.title }} {% endfor %}