Building data-driven web apps with Flask and SQLAlchemy Transcripts
Chapter: Jinja2 templates
Lecture: Concepts: Common layout
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Let's highlight some of the concepts
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around these shared layouts.
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We'll focus first on the base view
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or the outer shell, if you will
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the common view that is shared across
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all of the different ones.
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This is going to be in the templates folder
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in the shared subdirectory called _layout.html
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cause we got to refer to that in our other pages
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so it's good you know.
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Now, this can be really whatever you want
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it doesn't exactly have to be html
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you could probably generate xml fragments
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and stuff like that, as well
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but generally what it's for is html
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so you want to have a doctype html for html5
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and html block, tag, head tag, body tag and so on.
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These are just standard html Jinja2 files
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there's nothing you have to do special
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to indicate it's going to be used as one of these layouts
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other than define some blocks where code can go.
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So, here we're defining the main content block
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and providing a default value, no content
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if they don't fill it out.
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Okay, so here's a nice block, this is one
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pretty much every single page is going to be used
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and if not, you can put a little warning here.
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And also, because these blocks are optional
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they don't burden the consumers with them.
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So, it's not like if I have five blocks
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you've got to fill out all five little sections
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and if you get it wrong it crashes
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no, you can just ignore the stuff you don't use.
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Because of that, it's generally better to have more
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rather than fewer sections that these pages
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can punch holes in.
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You saw in our example we had the title
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we had extra CSS at the top, JavaScript at the bottom
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and we had our content block.
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Maybe you have even more that you want
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to make available or something like that.
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Be sure to think about how the pages
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might extend this shared layout
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and where those holes where they can punch
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common content might go.
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So, this is the shared layout, the outer shell
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often you can think of it as.
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And then, if we're going to consume it
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here we're in the index.html file from the home view.
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First we start by saying this extends
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the "shared/_layout.html" in quotes
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don't forget the quotes or you'll get weird errors there.
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Saying that it extends
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and then we just fill out these blocks
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here and there, and we say we're going to put some content
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you know, whatever the content of the index page is
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and this page happens to use Angular, so Angular 2.
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So, we want to make sure that we're including
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the Angular 2 JS stuff at the bottom.
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Not super practical or real, but you know
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it gives you an idea.
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Like, here's some additional JavaScript
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that this page needs to run that other pages don't
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so it's going to use this extra little hole
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this extra block in the layout page to fill it up.
