Building data-driven web apps with Pyramid and SQLAlchemy Transcripts
Chapter: Introducing the Pyramid framework
Lecture: Building block: Routes and URLs
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The next major building block to cover is routing,
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or routing, if you prefer British English.
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Routes allow us to define patterns that match
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some URL and map over to a particular view
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or controller method.
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Sometimes that just says, "This URL calls this function,"
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other times it says, "This URL contains Data,"
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so like /package/request or /package/sqlalchemy
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would pass the request or SQLAlchemy to that function.
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So, let's see how we do this in Pyramid.
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So, we're going to go to the main method
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in the __init__.py file
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that is basically the entry point or the start up
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for our web application, or we're going to
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start with this thing that's a configuration file reader.
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On there, it has a function called add_static_view.
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So here, we're naming the route static,
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and saying it maps to /static or anything under there.
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So, what we can do is we can go here and say
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anything in this directory or below it,
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will be cached by a quick little calculation.
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It's one month, so you've got to put an integer
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that is the number of seconds to cache it for,
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I like to put this as calculation so I can see
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60 seconds, 60 minutes, 24 hours a day, 31 days,
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okay, that's a month.
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Then we're going to define the routes
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that are the various URLs
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that go to our action methods.
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So the first one is /, just like that, and that's home.
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Right, that's just the basically the main page
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when you hit the site.
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And we want to have a /help
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so add a route for that for help.
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Then we're going to have, in our PyPI example,
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the route that they use for an individual package
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or the URL is /project/{package_name}.
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Now notice, this one is different.
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It has package_name as a curly bracket
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and then a variable looking thing.
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package_name will actually be passed to the function
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that we apply this to.
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So, like I explained before, SQLAlchemy, requests, whatever
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so the URL itself will carry the information along
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and that's defined in the route here.
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Also, we have things like account/login.
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And the final action to do is to tell the system to go
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figure out what functions are associated with these,
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so we have the route name, we also need to have to have the
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route to actually apply to this.
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So we run the scans and it looks through all
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the Python files, looks for that view_config decorator
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using various route names and then it
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puts those two things together.
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And finally, we have to return this WSGI application,
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W-S-G-I, WSGI, application that the web framework's
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going to use and this is just at the end
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of the main startup always.
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So this is how you define routes in pyramid.
