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Welcome back, everyone.

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And this lecture will talk about a couple of customisation options within the Django model form.

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I want to point out there's a lot more to model forms than what we're going to show here, and you can

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check out the documentation for even more features that are available to you.

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For model forms, but right now, we'll just go through some really common options that we can pass

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on as attributes inside the meta subclass.

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OK, so here I am back inside Visual Studio code.

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If we come to Forms DOP II, remember that we now have this model form with this meta subclass and we

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were able to manually define the fields.

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For example, if I only wanted the first name and the last name, I could just pass that in as a list.

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However, it's really common to want all the fields within a model to be within the fields of a form

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that is the model form.

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If you want that, you can say the following.

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In string, you say, underscore, underscore, all underscore, underscore.

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And that's essentially automatically the same thing as saying pass in all the model fields as form fields.

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OK.

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And we probably actually won't see a difference here if I refresh the page because essentially the same

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thing first name, last name and stars.

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What I do want to point out, however, is we can see there's some labels automatically created for

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you first name, last name and stars.

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Let's imagine we wanted to overwrite these labels.

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So what we can do is come back to the meta subclass and create a dictionary called labels.

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And in this dictionary, you essentially pass in the attribute name from the model like first underscore

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name and then the actual label you want to show up on the form.

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For example, I can say your first name in all caps.

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First name there we go, and we can do the same for the next one, so last name attribute can say last

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name.

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And then finally, we can also say stars, so stars attribute, let's just call that instead rating.

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So I'm going to save that.

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So come here, save those, and so now I should see these as the label, so again, the keys are the

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actual model attributes, first name, last name stars.

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And then this is the strings you actually want to show up on the web page.

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So I come back here to rental review form.

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Refresh this and I see in all caps your first name, last name and then rating.

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OK, now what's kind of interesting is if I try to submit something that maybe is greater than five

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than currently, it works.

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But let's imagine I actually added validators to my model to limit this so I could come back to models.

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And remember, there's a whole idea of core model value validator.

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So for example, I can say from.

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Django decor, the validators, and we've actually seen these before.

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I can get the min and max value validators, so I have a min value validator and a max value validator.

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And so as you're developing your model, maybe you can only have between one and five stars.

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So you say you're validators is an argument here and you pass those in as a list so I can get my men.

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Value validator pass in a minimum value of one.

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And then a max value validator and passing a minimum value of five, and sorry for all those pop ups

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that were covering the screen.

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But you get the idea again, we've seen this before.

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You just say from Django, the core validators and there's a bunch of validators you can look up in

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the documentation and you already know you can develop models those ways in order to have validation.

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And these validators, when you end up saving these changes and if you come back to views, those are

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automatically going to be checked for you.

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Inside is valid.

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So now models that PI has these men value and max value validators, however, haven't technically migrated

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those changes yet.

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So I need to quit the server.

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Say Python managed that pie, make migrations.

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And I should see, OK, I have altered the stars on review to have these validators here then actually

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need to run those migrations, python, manage the pie, migrate.

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And now I've altered those.

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So now actually have these validators existing.

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Let's see what happens when I rerun my website, but try to provide a star rating that's above five.

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So going to come back here, come back to rental review form again.

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Say, Let's say John Smith.

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And this time trying to say something that's above five, you can hit submit query and notice now nothing's

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actually happening.

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Well, what's going on is this form is no longer valid.

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So each time I try to submit this query, you'll notice it's going to give you a two step code.

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And if I come back to my admin view, if I were to go to cars reviews, I don't see a dozen reviews

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there.

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I just see the few ones that I've made this one I made before I actually migrated those changes to the

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model.

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So the question is, is there a way I can actually report back to the user?

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Hey, here's a little error message and you should, you know, show them something.

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Well, luckily for us, that's actually also done automatically through Django and Django forms.

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And what we're going to do first is make sure we're reporting that error inside the HTML.

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So if I come back to my HTML file, that's actually showing this form.

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So here I have rental review that HTML.

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Remember, right now I'm showing the label tag and the field.

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So there's another attribute called field errors.

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So what I can also say here is pass in.

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Field Dot.

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Errors save those changes, and now when you come back to the form, let's go ahead and do a test submission

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like for I'm going to refresh this real quick.

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And it's going to ask you, Hey, do you want to resend this information?

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Go ahead and say Resend.

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And actually recent the last pieces of information.

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So I'm going to say John Smith rating of four.

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Notice.

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I have a little warning here.

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I'm going to submit that worked.

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Let's come back here and now try to.

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I'm going to actually refresh this to cars.

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What's?

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Let's go rental review and now we have a fresh setting.

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OK, what happened was actually he probably should have just restarted the server because I did an HTML

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change here.

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But you get the idea.

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OK, let's let's bring in the review form.

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OK.

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So I have rental review form your first name, last name and rating.

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And what I added now was the fact that, hey, I'm going to actually report errors.

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So luckily for us, I can't pass on a name, so let's say.

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Joe Poe, and this is now going to be something that is no longer valid.

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Eight stars above five.

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If you submit the query, you notice there's this automatic unordered list item that shows up for you

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that says ensure this value is less than or equal to five.

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That's pretty incredible because what this is doing is it's automatically generating an error message

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for you, simply based off the max or min validators from this field.

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So that is a ton of heavy lifting that Django is doing for you, just from models up high.

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You should really take a time here to kind of in all of the workflow that jingles doing for you.

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Django is looking into your models, checking the validators of those models.

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Then recall we passed in that model to a model form that then gets sent to the HTML through the actual

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view, and you can easily call those errors for the person to see.

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And if you wanted to, you could put this in front of an if statement to maybe even add in more information

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to the user, like if field errors exist, show something or so a message to the user.

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Now what you can also do is beyond just edit the way this shows up through HTML.

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By default, it's an unordered list, but obviously you could edit the HTML to make this look like something

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else.

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And later on, we will discuss Django messages in general, but this is an automated piece of text that

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is basically linked to the validator.

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You could add in your own error messages.

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So the way that works is you come over here to the forms and just like you have labels, you can customize

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with the attribute error underscore messages.

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And then you decide the field you're interested in, in this case, I'm interested in stars field and

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then with that, you add in a key value pairing that has to do with the actual error message.

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This one's a little trickier to figure out.

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You do have to reference the documentation for the built in field classes and their possible error codes.

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So if you go to the documentation on if I bring it over here, built in field classes, they'll talk

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about the fields, the default widgets, and they'll also talk about the error message keys.

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So for example, we were on an integer field, so I'll go ahead and look that one up.

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Let's find the integer field on the page.

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And I see, OK, I have entered your field that gives you a default widget of a no input.

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And we can see if we scroll down, there were these validators and essentially error messages have to

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do with max value and min value.

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So the error message keys, which is what we're interested in, is max underscore value and min underscore

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value.

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So you don't actually call validators, you call these keys.

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So it's a lot to look up in the documentation.

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But essentially, each field beyond just having a widget also has error message keys available for you.

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And so the ones we're interested here are max value and min value.

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And the reason they're called error message keys is because they're going to be keys in this dictionary.

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So I can say.

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Men value.

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And then I can write my custom error message to make it obvious, I'm going to say, yo, then value

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is one, and then we'll say comma here.

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And let's now see max value for that key.

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And this one's going to be an obvious.

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Yo yo, max value is five.

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OK, go ahead and save those changes, and what I'm going to do here is I'm actually going to restart

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my server.

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And then let's come back to our rental review.

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So we'll come back to our rental review form.

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And again, it says first name, last name and reading.

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So let's say again, your poll here and let's give this a rating that's above five.

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Hit submit query.

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And now we have our custom message Yo max value is five.

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OK, so pretty amazing stuff that Django is doing for you.

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And there's a lot more to model forms than what we've discussed here.

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But this is essentially the key basics in order for you to connect a model quickly to a form and even

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begin to customize it quite a bit.

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And again, a lot of the things that were available to us within normal forms are available to us often

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model forms.

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For right now, we're going to leave it at that because we should really learn about class based views

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before we dive too deep into model forms, because class-based views are essentially going to automatically

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generate web pages for us with forms from a model class.

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But if you are interested in more details of model forms, the context on the actual documentation page

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is really amazing.

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They basically give you examples of every little thing you would want to do with a model form.

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So I highly encourage you to check it out.

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But hopefully just see right now how powerful this tool is for instantly creating a form for the HTML

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from the model.

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So as a final review, again to remember we have our normal models and then our model forms, which

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we end up passing in through the views we should check if it's a post requests, render that and then

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check if it's valid.

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Otherwise, create the form and then pass in a dictionary.

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And then we already know all the different variety of things we can do inside the templates itself.

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And typically we're going to do is try to aim for the HTML to be as simple as possible and more of the

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work being done in Python.

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But because we're a python Django, of course, not really an HTML focus course, but obviously you

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could make the workload happen on either end.

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All right.

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That's it for this lecture.

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I'll see it the next one.