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Now we talked a lot about how we can use the stitch to query data and how we can authenticate users,

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dive into the official docs if you want to learn more about that and how you can lock down access even

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more and how you have finegrained control.

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Now I want to talk about some other stitch features, briefly at least, to be precise

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I want to talk about functions and triggers because these are also two other major features. Now functions,

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this allows you to write some code that you can execute,

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let's click on create new function and let's name it greet,

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it will not do that much useful stuff but it will simply greet users. With that, default settings are

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ok, you can click save and now you can write your function code.

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Now you write javascript code and for all the features, again the official docs are the right place to

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go. In the end what you can do here is you can execute any javascript code, you can access other services, you

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can access your database,

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here's a snippet that shows you how that would work

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and you can also simply log something so that I can show you that this works. Not a super useful function

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but at least I can show you how we can call this. So I'll save my function code here

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and now I want to call this function and we can call it from inside our frontend, from our client application

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through that stitch sdk.

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Now let's say I want to call that function whenever my app loads,

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so essentially I can do this in the app.js file in the constructor after I initialized my client. Here

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I can use this client and then execute call function

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and here I simply pass a name to that function or the name of that function and that is of course greet

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and it will only look into my the stitch app which I initialize here and then find that function.

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You can also pass some arguments as a second parameter,

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so this would be an array of data you pass into the function, you can also have a look at this, can pass Max

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in there

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and now if I go back and edit my function slightly, I can also output arg here and see what I get

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there.

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So now let me save that and let me now reload my app and this should execute the function.

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I don't see anything here but on the backend, let's go to logs and there, we see a bunch of logs but

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we also see two function calls because the app was loaded twice because I save that before already.

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And there indeed you see greet

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Max as the output, so you see Max was the argument that was passed to the function and hence, I could also

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use it here.

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So it's as simple as that,

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that is already how I can call a function from inside my code.

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Important is that this function runs totally on a server,

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users cannot see your code in there,

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so if you got any code you want to execute that user should not be able to see,

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you can put it into a function and call that function from your frontend

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and then this code is invisible to your users and you can also put longer taking tasks in here for

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example, that you don't want to execute in the browser,

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stuff like that.

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Now you can also execute a function from inside or upon a trigger

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I should say, so we can go to triggers and we could add an authentication trigger to basically say

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ok, when a user was created or logs in or is deleted then I want to execute something, some function

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or a database trigger.

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Now let's go with a database trigger here,

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you can give it any name you want,

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I'll name it product insert, should be enabled and I'll listen to an event in the shop database and

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there in the products collection and I'll listen to an insert. Whenever something is inserted into this

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collection in this database,

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then I want to execute a function, to that function I'll pass the full document which was inserted as an argument

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and then I'll execute my greet function let's say. You can now click save and that is already it, what

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you can now do is you can go back to your app and log in real quick and if I now add a product

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and I'll really just type in some dummy data here so that we can quickly create it.

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Now that I created it,

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if we go back to the logs here in our stitch console, you'll see product insert, that trigger was executed

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and you see the output of the result is greet and then a more complex object in the end because that

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function receives the full document and some other metadata and therefore

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this is not output here

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essentially. If you want to see what's being passed in detail, you can of course dive into the official

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docs or maybe write this object into some dummy collection,

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you can insert that object into a dummy collection to then also see what's in there.

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And these are functions and triggers, very useful features that allow you to write code that runs on the

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server and even control that this code should always run when something happens to one of your collections.