All language subtitles for 003 Data Validation with Mongoose_en

Now as we mentioned earlier, by using and incorporating Mongoose into our app it makes validation of

data entry a lot easier.

Instead of having to write our own assert statements all over the place and specifying specific things,

we can actually use Mongoose's built in validation checks to make it a lot easier and a lot quicker to

use.

So I'm going to delete all of this part

where we have the kiwi, orange, banana and the insertMany.

Now if you want to keep it around for reference then just go ahead and comment it out.

If you scroll to the top where we created our fruit schema, one of the things that you can do is instead

of having the value of each of these key value pairs being simply just the data type

because this is the only thing that is strictly required when you are creating the schema,

instead you can actually add in some validation.

So let's go ahead and delete that data type and instead I'm going to open up a set of curly braces.

Now inside the curly braces I can add back that type which is going to be Number but I can also add

some validation.

So for example, what if when we're adding new data to our fruits collection the rating that we give to

each fruit we want a limited between 1 and 10?

So if somebody gives a rating of 99, then that shouldn't be valid right?

So how would we do that using Mongoose?

Well if we head over to the Mongoose documentation and you click on validation, then you can see that

there's a whole page dedicated to explaining how you can use the built in validators that Mongoose has

in order to make your data comply with a certain format and validate your data to keep it clean.

Down here you can see that all schema types have the built in required validator.

So you can make a particular property required. That is usually for example if you were going to implement

an ID, then it probably should be required.

But there's other things such as for the number data types,

you can have a minimum and maximum validators.

And if we click on that, it explains to us how you can use it. The minimum is going to be a number

and it creates a validator that checks if the value is greater than or equal to the given minimum.

And max does the same thing for the maximum.

So that means over here for our rating, in order to keep all the new data that we enter into our database

have a rating that's between 1 and 10

then we can specify the min as 1 and the max as 10.

So now if we hit save and let's just change this part to have a rating of, I don't kow, 34

right?

And let's uncomment the fruit.save to save it in there and comment out the person.save so

that we don't save any new persons, then if we go back and run on node app.js, you can see we get

a error. And it tells us that there's a validation error

and the problem is that fruit validation failed.

The rating is 34 and it's more than the maximum allowed value which is 10.

And when we look at the fruits that are being printed out, you can see that new fruit, the apple, didn't

get added again because this is a fatal error.

So it prevents data that doesn't match the validation to be inserted into our database thus keeping

our database sanitized and clean and have all of the data in a format that we expect it to be.

Now what if accidentally I added in a new document and I forgot to give it a name?

So for example I was adding some peaches in there and peaches are lovely, so I'm going to give it a rating

of 10. And let's just give it a review as well

"Peaches are so yummy!".

And let's hit save and try to save that fruit into our database,

well nothing bad happens.

If you check through our database you can see that that new thing got added right at the bottom here.

It has a review,

it has a rating but it doesn't have a name which is quite bad

if we want to loop through our data and print out everything that has a name right? It doesn't work and

it'll break our code later on down the line.

So as a challenge, I want you to make the name field required and this means that you might have to look

through the documentation on Mongoose. But you should make it such that when we try to add a new fruit

that doesn't have a name then it will refuse to add that entry into our database.

pause the video now

and give that a go.

Okay. So if we take a look at again the validation part of the Mongoose documentation and we look at

the built in validators,

it already specifies that there is a required validator. And you can see that in the example down here

they've actually implemented it for us. For example for the bacon field

they've opened up a set of curly braces and they've specified an object in here. And it says that all

bacon fields have to have a value that is a number.,

so how many bacon have you got for your breakfast

in this case. And then they have the required field in there which they've set to true.

They've also given a message in the case when a piece of data is being added to the database without

specifying a value for the bacon field.

Let's try and replicate that in our code. Here in the schema again we're going to change the name part

from string to a object and it's going to have a type of string.

So we're going to keep that the same. But we're now going to add the required option and we're going

to set that to true.

So you can use one or you can use true, whichever one you find easier to understand.

Now next we can optionally specify a message. So we can say when a new piece of data is being added to

our fruits collection

and they didn't specify a name, we should say that

"Please check your data entry,

no name specified!".

So now let's hit save. And let's try to do the same thing that we pulled last time which is adding a

fruit with no name and try to save it to our database.

You can see now we're getting a validation error and it tells us that fruit validation failed and the

field that's causing a problem is name. And it's printing out that message that we specified,

"Please check your data entry,

no names specified!".

That's pretty failsafe right?

And if we check our data, you can see that we didn't get any new entries added to our data.

We've only got apple, kiwi, orange, banana, and that peach that didn't have a name before we added in the

validation.

But this new one didn't get added.

So there's a lot of other built in validations that you can check out on the Mongoose documentation

page. But that's just a quick intro into how you might use it and how easy it can be to keep your data

clean and validated against certain preset rules.