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- [Instructor] Hi and
welcome back to the course.

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In this video, we're finally going

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to look into the item list resource

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and we're going to make it
use the item model as well.

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Let's go into our resources
and then look at our item.

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The first thing I'm going to do is,

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I'm going to remove the import for sqlite,

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because at the end of this video,

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we're not gonna need that again.

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And then we're gonna go down
here into the get method

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and we're also going
to delete all of that.

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So what is it that we have to do now

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to get exactly the same
that we had before?

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So as a reminder, the item list returned

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items is a list of item.json.

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Item.json here.

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How are we gonna get that?

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Well I'll give you a hint.

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We're gonna return this.

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It's all gonna be in one line.

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And we're going to use SQLAlchemy.

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We're going to use the ItemModel.query.

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And remember this is a query builder

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and it has a .all method.

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.all returns all of the
objects in the database.

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That's not how we do it,

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but you're gonna need that to
complete this small challenge,

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so go ahead and pause the video

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and give it a bit of thought.

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How would you do that?

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Knowing that ItemModel.query.all

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gives you all of the objects,

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how would you return the json

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that you need to return in this method?

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Hopefully you've got that,

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or pause the video if you need more time.

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But the way I would do it is
with a list comprehension.

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I would do item.json

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for item in ItemModel.query.all.

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How easy is that,

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compared to the massive
spew we had there earlier?

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And best of all, this makes sense.

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We're just getting all of the items

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and then we're iterating over them.

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We no longer have to concern ourselves

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with rows and data and
cursors and result sets.

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We're just getting all of the items

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and then applying the
function of the item,

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of the object in each iteration.

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Now for completeness'
sake, I will also give you

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the way that you could do it

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without list comprehension
using Lambdas if you prefer.

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So we can do that as well.

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That way that you would do using Lambdas

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is you would say, list
of the filter lambda x.

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Sorry, not filter.

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List of map, lambda x.json

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for ItemModel.query.all.

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Okay?

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And once again, what this would do,

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is it would apply this function

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to each element in this list.

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Okay, so that mapping is a mapping

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of functions to elements.

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And then it would make that into a list.

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So it would just essentially
do the same thing.

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The list comprehension
way is more Pythonic.

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If you're programming in Python only,

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it is slightly better.

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It's more readable, at least I think so.

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And I like it and the
Python community in general

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likes it better.

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I've heard claims that
it is more performing,

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it is faster,

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which is possible, I'm not really sure.

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I think it's about the same
from the stats that I've read.

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So you should only use the map

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if you are also programming
in other languages

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or if you're working with people

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programming in other languages, too.

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That will find the list on
the map easier to understand.

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Okay?

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In addition, the map
filter, reduce methods

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are more stackable.

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So you can reduce a map

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or you can filter the
reduce of the map and so on,

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whereas it's not so easy
to use list comprehensions,

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inside list comprehensions.

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It gets confusing quite quickly.

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If you have to do something like this,

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I would use a list comprehension

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unless you're working with people

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programming in other languages

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or part of your project
is in a different language

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that you are using map,
reduce, and filter in.

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So for example,

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if a lot of your project is in JavaScript,

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and you're using filter
and map in JavaScript,

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you probably want to use
map and filter in Python.

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If you're only working in Python,

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you're responsible for the Python code.

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You might as well use list comprehensions.

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I think it's slightly more readable.

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Okay, so that's everything for this video.

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Quite a short one there,

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but nevertheless,
remember what I'm saying.

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It's important that you remember,

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other people may be reading
things differently from you

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and may be more accustomed
to other code than you are.

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So it's important to
work on a team like that.

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Well that's everything for this video.

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So thanks for watching and
I'll see you on the next one.