Step by Step

We have courses, but each curse should have steps to it. 0:00 Maybe it will be videos, or maybe it'll be text based steps, or 0:03 images, whatever method you want to teach with. 0:06 Since I don't know what your step of choice will be and 0:08 we're not gonna deal with video or image uploads. 0:11 We'll just call them steps. 0:13 Anyway, let's get to it. 0:15 So since steps are a logical part of our courses, we'll keep them in the same app. 0:16 So let's close some of this stuff up again. 0:22 It gets a little unwieldy at times. 0:25 So inside courses, inside models.py, we're gonna add our new model. 0:29 And we'll say class Step(models.Model). 0:39 So what goes into a step? 0:44 Well I think a title deserves to be there. 0:45 And this will again be a char field of, 0:49 255 characters or less. 0:54 I think we would have a description just like our course would be. 0:58 So so far a step and a course are the same thing just the created app. 1:04 I think we would have an order field, 1:09 so that we could specify what order different fields come in. 1:11 And we'll set the default on this as zero, and then let's do a course, 1:17 and this will be a foreign key, and this will link back to course. 1:23 And since we know we're going to print these out eventually, 1:32 let's do return self.typo. 1:35 Okay, so there's a lot here, the first two items should be pretty familiar from our 1:37 course model, they're exactly the same. 1:42 The last two items though are new, and I briefly went over them but 1:44 let's talk about them a bit more. 1:48 Order lets us control the order of steps. 1:50 Maybe we forget to create a step and we have to create it later. 1:53 This way, we can add a new one, and we can set where it should be in the order. 1:56 Setting it to zero makes it so 2:00 we can set other numbers to control the ordering of steps later. 2:01 There are other solutions to this. 2:04 you could have them auto-increment. 2:06 You could set them at a negative, like, there's different ways to do this. 2:07 Zero is a pretty safe default. 2:12 That we ordered automatically by their ID, and 2:14 then we'll handle the other ordering later. 2:18 And then, the course attribute is a foreign key. 2:20 And a foreign key is a record or a column that points to a record in another table. 2:23 Can be on the same table, but for now it's in another table. 2:30 So, what we're doing is we're saying, hey here's this step. 2:32 And maybe this is a step ID of three and it belongs to the course with 2:36 an ID of one, so it belongs to that course over there and points to that course. 2:42 This way, a single course can have multiple steps, but 2:48 each step only has one course. 2:53 This is what is known as a one to many relationship, or 2:56 we're looking at it from the step side, a many to one. 3:00 Many steps belong to one course. 3:03 And then of course we have our Dundar STR method, 3:06 which will print out the title of the step. 3:09 You might want to print out the order but 3:10 I'll let you put that in there if you want. 3:12 So now that we've made our our model. 3:14 Got ahead of myself. 3:17 Now that we've made our model, we, of course, have to create a new migration. 3:18 You'll do this dance a lot. 3:22 You'll make a model, then you'll make a migration, 3:25 and then you'll apply the migration. 3:28 It might seem monotonous and 3:30 time consuming, but it's good to know exactly what's going on behind the scenes. 3:32 So, let's do this. 3:35 Python manage.py, make migrations for courses. 3:36 Hey, we had to make one, cool. 3:42 Python manage.py, 3:44 migrate courses. 3:49 Done. Applies all my migrations. 3:53 Okay. 3:54 So we've made our model. 3:55 We can play with it in the shell if we want to. 3:56 But, I think it's easier just to stick it in the admin and 3:59 then go mess with it in the admin. 4:01 And I bet you agree with me. 4:03 So let's run the server again. 4:05 And then shrink our terminal down. 4:08 And let's go look at admin.py. 4:12 And let's import Step and let's copy and paste this line and change Course to Step. 4:15 So we've imported it, we've registered it, things are cool right? 4:22 Let's go back to our admin and check it out. 4:26 /admin, there's our steps, there's our courses. 4:27 Okay, so let's go add a step. 4:35 So, we'll add a step, give it a title, and we'll say What's the deal with strings? 4:37 Strings are more than just a bunch of letters. 4:46 Find out why! 4:52 Okay, and the courses belongs to, this is course of Pythons basics step. 4:56 So let's go ahead and save that. 5:01 Cool, now this isn't terrible but 5:03 we if we had a lot of courses this might get really difficult. 5:05 That drop down, that can take a while to read through and find stuff. 5:08 Probably a better way, and you know I wouldn't ask that unless it was true. 5:13 Django lets us create smaller forms that represent another model 5:17 inside the admin form for a model. 5:21 So we can edit and create steps for our courses while we're editing and 5:24 creating a particular course. 5:27 We need to create two new classes for this to work though. 5:29 So let's hop back over to our editor. 5:32 I get to do all of them right here inside admin. 5:35 So now first we need to make the class for 5:38 our smaller form and that's known as an inline. 5:40 So we're gonna say class StepInline(admin.StackedInline). 5:43 Now there are two types of inlines. 5:50 There are stacked inlines and tabular inlines. 5:52 We're gonna use the stack version, but feel free to switch over to tabular and 5:55 try that out. 5:59 And we said our model is equal to step, now that's it. 6:01 On it's own, this doesn't do anything, but this creates the inline. 6:06 So now We have to make our next thing, which is our course admin. 6:11 This is the admin for handling our courses. 6:16 This let's us specify custom special things. 6:20 So this is (admin.ModelAdmin) and we're gonna set inlines = [StepInline,]. 6:23 All right, now this is the one thing that's a little bit weird. 6:32 When we made this StepInline, we set model = Step. 6:35 We didn't set a model on course admin, we do there here. 6:39 So we register course, and then we register it with course admin, okay, and 6:42 if we want we can delete this, but let's leave it alone for right now. 6:47 So let's come over here and look at this again, let's go back to courses. 6:50 Courses, and let's look at Python basics because we know it has a step. 6:54 Python basics, and look, here's our step. 6:59 What's the deal with strings? 7:01 Strings are more than just blah blah blah, there's the order. 7:02 Here's where we can add a second one, and a third one, and a fourth one, and 7:04 if we need to add more we can click add another step. 7:09 So that's pretty awesome, we can edit, delete, and 7:11 we can add new steps right here in the admin. 7:13 There's a lot more that we can do with inlines but this is enough for now. 7:17 I've linked to more documentation on them in the teachers notes though, so 7:20 feel free to explore them some more on your own 7:23