Django Tutorial for Beginners - 16 - Raising a 404 HTTP Error Video Lecture | Django: The Ultimate Beginners Guide - Back-End Programming

ah right yeah so we got our template set
up looking good
and check this out so whenever we click
read it's going to take us to the
details view for that Taylor Swift album
whenever we click skatepark is going to
take us to the details view from that
band that I you know I knew in high
school but check this out
whenever we go to the URL like forty
three hmm you see we don't have an album
with ID of forty three yet our web page
is going to try to display this and
that's usually not a good thing because
what we want to do is if the user or if
we go to a website and we don't have the
resources to actually display
information we want to send a 404 so I
know you guys have been in those
websites before it says 404 error that
means that I don't know like maybe
someone made a post and deleted it or
maybe someone like had a item on their
shop for sale but it got sold out so
they just deleted it basically a 404
means we don't have the resources to
display or it got deleted or something
like that
now that's the proper way to do things
so that's what we're going to want to do
in Jango so in order to use these four
or four messages you do this so from
Jango HTTP import HTTP 404 art so let's
go ahead and make it for that details
view so the first thing I'm going to do
in here is just make a details template
so new HTML file I'll just name it a
detail alright so we can get rid of this
for now in our details template we won't
worry about what exactly is inside there
right now but we do know that we're
going to want to not return this all
right now instead of just returning some
HTTP response without even checking if
the ID is valid what we want to do is we
want to try to query the database and we
want to see if there's album with the ID
that they typed in if there is then we
can just go ahead and display this
template but if there's not then instead
of sending back a normal respond
so we want to send back an HTTP 404
response so what we do is we make a try
accept statement and I'm just going to
first go ahead and try to get their
album ID so say album equals album
objects and you remember how we get a
specific album just one of them we
either have to use PK or ID doesn't
really matter and this is going to be
equal to whatever ID they passed in so
we're going to look for the album with
the ID of one or two or seventy-four
whatever now most of the time as long as
the ID is valid then this is going to
work perfectly however if they type
something in like 700 and we can't get
that item then what it's going to do is
it's going to generate an album does not
exist air
so we'll say except album does not exist
that means that hey arm that album you
know maybe it was a typo maybe it got
deleted or whatever but we don't have it
in our database anymore so how do we
handle this well to send back this 404
response
it's called raising not raisins it does
sound kind of get the raisins HTTP 404
and this is actually a function where
you can pass in a message and then that
message gets displayed um included in
your 404 so I say album does not exist
alright so hopefully they don't get that
but you know they might who knows now
another thing I want to do is just use
this shortcut because that's a lot
faster than you know what we learned
before and I'll show you guys even a
cooler way so you know how before what
we did is we made this context which is
basically information that your template
needs to work and we set it equal to a
dictionary well any time you have
variable and you don't use it multiple
times you see how we just use this one
other time then what you can actually do
is you can actually just take the value
of it
and use that instead so variables are
just for whenever you have a value and
use it over and over and over again in
your program whenever you don't and you
just use it once then you should
probably just set equal to the value
unless the values like something big
like you're reading at a document or
something so for this we're just going
to throw in the album information and
boom Russ that everything is good to go
and actually this import right here HTTP
response we aren't even using that for
anything since we're just using render
for everything so we can just delete
that clean up our code even more and
let's clean this up even more while
we're here all right so look how
condensed our code is yet we're learning
more funny how things are alright so in
our detailed view we probably should you
know show something what are we going to
show what is through this album so we'll
just show the default view or the
default string representation of that
album and oops almost forgot this is the
detail that HTML so this is the template
that we're using for the detail view and
all right let's so let's go ahead and
refresh this make sure everything is
up-to-date and check it out so whenever
we go to this URL music slash one
it displays red taylor swift skatepark
slash myth and we can do this all day
now if the user ever tries to do
something stupid like go to 54 then it's
going to say page not found and this is
our 404 response now this is what I was
talking about elbowing does not exist if
you want to give them a little clear
indicator of why they are getting this
again this is optional but it's always a
good idea to do so there you go noise
made this is actually a pretty fun app
if he asked me alright so so far we
learned a bunch of stuff how to use
templates for form messages but still
there's a lot of crap to cover so yeah I
think guys for watching don't forget to
subscribe I will smell you guys next
time