Are server actions sent to a client before execution?

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Asiatic Lion posted this in #help-forum

Asiatic LionOP

2024-01-26T16:08:20.000Z

Hey!

I'm reading nextjs docs and I don't understand something.

https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations#closures-and-encryption

Below the example (see the link above), docs says:

...the captured variables are sent to the client and back to the server when the action is invoked.

I thought server actions run only on a server, like server components. Why would nextjs send captured variables inside of a server action to a client? Can you give me some information on this, please?

12 Replies

@Asiatic Lion Hey! I'm reading nextjs docs and I don't understand something. https://nextjs.org/docs/app/building-your-application/data-fetching/server-actions-and-mutations#closures-and-encryption Below the example (see the link above), docs says: `...the captured variables are sent to the client and back to the server when the action is invoked.` I thought server actions run only on a server, like server components. Why would nextjs send captured variables inside of a server action to a client? Can you give me some information on this, please?

Ray

2024-01-26T16:10:50.000Z

the captured variable will be sent to client and render as a hidden input inside the form element.
So when the form submit, it will send the request to server with the value

@Ray the captured variable will be sent to client and render as a hidden input inside the form element. So when the form submit, it will send the request to server with the value

Asiatic LionOP

2024-01-26T16:15:47.000Z

why send this variable to a client?
idk how server actions work under the hood. I thought they are just saved on a server somewhere and they invoke and do some stuff when you submit forms.

@Asiatic Lion why send this variable to a client? idk how server actions work under the hood. I thought they are just saved on a server somewhere and they invoke and do some stuff when you submit forms.

Ray

2024-01-26T16:16:42.000Z

from this example, publicVersion is defined outside of the function of server action

if your server action doesn't use any value like this, no variable will be sent to client

@Ray if your server action doesn't use any value like this, no variable will be sent to client

Asiatic LionOP

2024-01-26T16:20:54.000Z

why publicVersion is being sent to a client if this variable is located in a server component that run only on a server? in jsx there's no sight of publishVersion, why send it?
im sorry, i dont understand

@Asiatic Lion why `publicVersion` is being sent to a client if this variable is located in a server component that run only on a server? in jsx there's no sight of `publishVersion`, why send it? im sorry, i dont understand

Ray

2024-01-26T16:21:26.000Z

Closures are useful when you need to capture a snapshot of data (e.g. publishVersion) at the time of rendering so that it can be used later when the action is invoked.

this is trying to prevent if the page open with a user and the data already updated by other user

so it throw an error if the page is not the latest version

so you don't need to render the version manually in the form

Asiatic LionOP

2024-01-26T16:30:18.000Z

I'll go and read on this more. Will try to run some examples on my machine. Still don't understand) Thanks for trying to help me

@Ray the captured variable will be sent to client and render as a hidden input inside the form element. So when the form submit, it will send the request to server with the value

Asiatic LionOP

2024-01-26T16:38:33.000Z

what these hidden inputs for?

I thought when you send this line to a client
<button action={publish}>Publish</button
client will get smth like:
<button action={yourserverdomain.com/serveraction12345}>Publish</button>
So when you click a button, you just being redirected to some url where this server action is located

@Asiatic Lion what these hidden inputs for? I thought when you send this line to a client `<button action={publish}>Publish</button` client will get smth like: `<button action={yourserverdomain.com/serveraction12345}>Publish</button>` So when you click a button, you just being redirected to some url where this server action is located

Ray

2024-01-26T16:40:03.000Z

yeah, you gotta try building something with form first