Building data-driven web apps with Flask and SQLAlchemy Transcripts
Chapter: User input and HTML forms
Lecture: Login code
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0:00
With our login form in place
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let's go write the code.
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So, this is really all we need for that initial part.
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But the bottom is actually so much like Register.
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We're just going to grab what we did up here
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and put it down there.
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So this part comes like so.
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There's a few things that we can skip.
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We don't need to get their name, that doesn't matter.
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We don't need to validate the name.
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We're actually going to use a cool pattern
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that moves this validation elsewhere.
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So that's going to be real, real nice.
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Do this, we're going to validate get the user
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something like that.
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Here we're going to say, login_user.
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And we don't need the name.
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So that's another function we have to write.
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And then, let's just add a quick message
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if you can't login. Something like that.
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All right, then we still need to do our browser login
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we'll deal with that in a little bit.
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But let's just go right of this function here.
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This is going to be a string, and just like before
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it's going to return an optional user.
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Super, okay so what we need to do, it looks a whole lot like
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up here, we're going to go and create a session
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and then we just need to return the user
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that we're going to query for.
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Actually, it seems like you could create for
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but actually no, the way the password works
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we can't quite just query.
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so what we're going to do here is
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we're going to go to the session
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and we're going to do a query of user
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and do a filter, with a user email
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is this email, now first.
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Now it seems like you might say
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well and the password equals such and such.
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But remember what we're storing is the hashed version.
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And we can't recompute the hash ever.
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Once it's computed, it's fine.
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But we can't recompute it
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'cause this randomly mixes in different result every time.
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So it'll never give you the same answer.
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But we can verify it.
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So the way we have to do this is get it back
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first check there's no user, return None
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or the user would be the same.
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And then we have to validate.
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We can say, if not verify_hash.
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What does this take?
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It takes the hashtags
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which would be user.hash_password.
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And the plain text which would be password.
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So that's not the case, also none
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we don't find the user by email
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or if we do find them but they have the wrong password
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we don't give them back, otherwise, we return user.
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Make sure you don't forget any of those steps
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that would be super, super-bad.
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Right, so now we've got to user
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we send it back.
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Looks like everything may be good.
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Now what do we do?
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Then we're going to validate the user
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we're going to check their password
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and either make sure that account exists
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and the email's right.
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We still got to do this little login.
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Then we're going to go to our account page.
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We should be able to test that real quick here.
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So let's go back to our login page.
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And we'll just do that.
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Let's just try empty.
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Ah, some required fields are missing.
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Put the letter a, tries to get to it.
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Account does not exist.
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Put the real password.
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if this passes gets the user back
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it should redirect us over to our account page.
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Bam, it does! All right, so.
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Login, that was quick and easy, right?
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Starting to get the feel for these forms
3:18
in this database interaction.
