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Now as we mentioned earlier, by using and incorporating Mongoose into our app it makes validation of
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data entry a lot easier.
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Instead of having to write our own assert statements all over the place and specifying specific things,
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we can actually use Mongoose's built in validation checks to make it a lot easier and a lot quicker to
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use.
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So I'm going to delete all of this part
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where we have the kiwi, orange, banana and the insertMany.
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Now if you want to keep it around for reference then just go ahead and comment it out.
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If you scroll to the top where we created our fruit schema, one of the things that you can do is instead
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of having the value of each of these key value pairs being simply just the data type
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because this is the only thing that is strictly required when you are creating the schema,
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instead you can actually add in some validation.
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So let's go ahead and delete that data type and instead I'm going to open up a set of curly braces.
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Now inside the curly braces I can add back that type which is going to be Number but I can also add
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some validation.
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So for example, what if when we're adding new data to our fruits collection the rating that we give to
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each fruit we want a limited between 1 and 10?
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So if somebody gives a rating of 99, then that shouldn't be valid right?
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So how would we do that using Mongoose?
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Well if we head over to the Mongoose documentation and you click on validation, then you can see that
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there's a whole page dedicated to explaining how you can use the built in validators that Mongoose has
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in order to make your data comply with a certain format and validate your data to keep it clean.
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Down here you can see that all schema types have the built in required validator.
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So you can make a particular property required. That is usually for example if you were going to implement
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an ID, then it probably should be required.
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But there's other things such as for the number data types,
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you can have a minimum and maximum validators.
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And if we click on that, it explains to us how you can use it. The minimum is going to be a number
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and it creates a validator that checks if the value is greater than or equal to the given minimum.
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And max does the same thing for the maximum.
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So that means over here for our rating, in order to keep all the new data that we enter into our database
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have a rating that's between 1 and 10
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then we can specify the min as 1 and the max as 10.
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So now if we hit save and let's just change this part to have a rating of, I don't kow, 34
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right?
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And let's uncomment the fruit.save to save it in there and comment out the person.save so
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that we don't save any new persons, then if we go back and run on node app.js, you can see we get
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a error. And it tells us that there's a validation error
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and the problem is that fruit validation failed.
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The rating is 34 and it's more than the maximum allowed value which is 10.
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And when we look at the fruits that are being printed out, you can see that new fruit, the apple, didn't
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get added again because this is a fatal error.
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So it prevents data that doesn't match the validation to be inserted into our database thus keeping
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our database sanitized and clean and have all of the data in a format that we expect it to be.
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Now what if accidentally I added in a new document and I forgot to give it a name?
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So for example I was adding some peaches in there and peaches are lovely, so I'm going to give it a rating
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of 10. And let's just give it a review as well
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"Peaches are so yummy!".
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And let's hit save and try to save that fruit into our database,
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well nothing bad happens.
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If you check through our database you can see that that new thing got added right at the bottom here.
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It has a review,
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it has a rating but it doesn't have a name which is quite bad
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if we want to loop through our data and print out everything that has a name right? It doesn't work and
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it'll break our code later on down the line.
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So as a challenge, I want you to make the name field required and this means that you might have to look
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through the documentation on Mongoose. But you should make it such that when we try to add a new fruit
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that doesn't have a name then it will refuse to add that entry into our database.
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pause the video now
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and give that a go.
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Okay. So if we take a look at again the validation part of the Mongoose documentation and we look at
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the built in validators,
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it already specifies that there is a required validator. And you can see that in the example down here
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they've actually implemented it for us. For example for the bacon field
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they've opened up a set of curly braces and they've specified an object in here. And it says that all
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bacon fields have to have a value that is a number.,
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so how many bacon have you got for your breakfast
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in this case. And then they have the required field in there which they've set to true.
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They've also given a message in the case when a piece of data is being added to the database without
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specifying a value for the bacon field.
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Let's try and replicate that in our code. Here in the schema again we're going to change the name part
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from string to a object and it's going to have a type of string.
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So we're going to keep that the same. But we're now going to add the required option and we're going
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to set that to true.
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So you can use one or you can use true, whichever one you find easier to understand.
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Now next we can optionally specify a message. So we can say when a new piece of data is being added to
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our fruits collection
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and they didn't specify a name, we should say that
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"Please check your data entry,
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no name specified!".
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So now let's hit save. And let's try to do the same thing that we pulled last time which is adding a
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fruit with no name and try to save it to our database.
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You can see now we're getting a validation error and it tells us that fruit validation failed and the
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field that's causing a problem is name. And it's printing out that message that we specified,
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"Please check your data entry,
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no names specified!".
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That's pretty failsafe right?
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And if we check our data, you can see that we didn't get any new entries added to our data.
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We've only got apple, kiwi, orange, banana, and that peach that didn't have a name before we added in the
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validation.
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But this new one didn't get added.
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So there's a lot of other built in validations that you can check out on the Mongoose documentation
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page. But that's just a quick intro into how you might use it and how easy it can be to keep your data
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clean and validated against certain preset rules.