Tags (for, if, else)

Quick reference

• 00:04 Okay, in this video I want to talk about tags and tags are sort of the last thing
• 00:07 in Django template language that we're going to look at.
• 00:10 So I'm back at the same documentation page that we've been looking at in the last
• 00:14 few videos.
• 00:14 We can just come over here and click on Tags to skip down to the tags section.
• 00:18 And tags allow us to do certain Python programming type things on a web page.
• 00:25 So if you're familiar with Python or any programming language, the main basic
• 00:28 things you do with programming languages are you use variables.
• 00:32 We talked about those in the last couple of videos.
• 00:34 You also do logic, if else statements.
• 00:37 And you also loop through lists.
• 00:39 Those are sort of common programming language things.
• 00:42 And tags allow us to do all of those things on a webpage.
• 00:46 So specifically we're going to look at if else statements and for
• 00:50 loops that allow us to loop through things.
• 00:53 So if you're familiar with programming, you know what an if else statement is and
• 00:57 you know what a loop is.
• 00:58 So I'm just going to kind of go over this very quickly.
• 01:00 But to use a tag, we just use the same opening and closing brackets that
• 01:04 we've been using, and then call the thing that we want to do.
• 01:06 So if we want to do an if statement, we just call if.
• 01:09 If we want to do a for loop, we just call for.
• 01:11 So let's take a quick look at this in an example.
• 01:14 So let's go to our views.py file and
• 01:16 we have a first name of John that we're passing in through our context dictionary.
• 01:21 So let's do some logic on our about page.
• 01:24 So let's get rid of this stuff from the last couple of videos here,
• 01:28 clean this up a bit.
• 01:29 So I'm just going to create an if statement.
• 01:32 So let's say if first underscore name, which is that context variable,
• 01:36 equals John, and you'll notice I use double equal to signs,
• 01:40 that's what you always want to do in Python with an if else statement.
• 01:45 So if the first name is John, let's print out on the screen,
• 01:51 hello John, right, else let's print out hello stranger.
• 01:57 And with these tags, you always want to close them.
• 02:02 So to close and if tag for instance, we would end if,
• 02:06 if this was a four tag we would end for.
• 02:09 If this is a block, we end block.
• 02:11 Like right here, right, you see sort of the way this usually goes.
• 02:17 So end if and let's go ahead and save this.
• 02:22 Now let's head back over to our webpage and let's reload our about page and
• 02:25 it says, hello John.
• 02:27 And that's exactly what we would expect it to do.
• 02:30 So let's head back over to our views.py file and
• 02:33 let's change the first name to Bill.
• 02:35 So if we save this, then head back over to our about page and hit Reload.
• 02:40 It says, hello stranger.
• 02:41 Why?
• 02:42 Because the first name is no longer John.
• 02:44 If we pull up our code, it's saying if the first name is John say hello John,
• 02:50 else otherwise, print out hello stranger.
• 02:53 So, very cool.
• 02:55 And we could also use our variables inside of here.
• 02:59 So we could say, print out first underscore name.
• 03:03 So if we save this and come back and hit reload, it's going to say hello Bill.
• 03:07 So very, very cool and pretty simple.
• 03:09 So next, I want to show you very quickly a for loop.
• 03:12 So let's do this in our homepage.
• 03:14 So let's create a list, let's call it names.
• 03:17 And if you're familiar with Python lists,
• 03:20 you just use square brackets and then inside of here,
• 03:24 we just use parentheses, and we just make a list of whatever we want.
• 03:29 We want a list of names.
• 03:30 So let's go John, Steve, Bill, Mary, each one separated by a comma.
• 03:36 So now we can pass this names into our context dictionary
• 03:41 like we've done before and we want it to be names.
• 03:46 So now we can access this names on our webpage.
• 03:48 So in our homepage, let's create a quick for loop.
• 03:52 Let's get rid of this from the last couple of videos,
• 03:55 and let's put another line break to make it easier to see.
• 04:00 And to do a for tag, we just go for, and
• 04:02 now we need to create a variable name a dummy variable.
• 04:06 Well we're working with something called names plural.
• 04:10 So let's say name.
• 04:12 So for each name in names, we want to do something.
• 04:16 What do we want to do?
• 04:17 Well, let's just print out name, all right?
• 04:21 And let's put a line break so they're one on each line.
• 04:24 And finally, we need to close our tag.
• 04:28 So it's just end for because this is a for loop, so we need to end the for.
• 04:33 So let's go ahead and save this and head back to our homepage.
• 04:37 And what we do, we see John, Steve, Bill and
• 04:40 Mary printed out one at a time on a separate line.
• 04:43 And it's just looping through that whole list that we have, which is this list.
• 04:48 And it's just printing out the names under the screen.
• 04:52 So very cool, those are tags, those are for tags, and if else tags.
• 04:56 Very useful, you're going to use those for
• 04:59 all kinds of different things in Django, and pretty cool.
• 05:03 So in the next video,
• 05:04 I want to talk about using external Python programs in your Django code.

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