feat: Add @validate directive for custom scalar validation

[amitksingh1490]

Description: Currently, Tailcall allows developers to define custom scalars. However, there's no built-in way to add validations on those custom scalars. I propose creating a @validate directive which takes js function as input and can be applied on scalars. The js function inside @validate should return either true or false. If it returns false, the user should receive a Evaluation error when an invalid value is passed into the scalar.

Expected Behavior:

• The @validate directive should be applicable to custom scalar types.
• The directive js function should return true for valid values and false for invalid values.
• If the directive returns false, a Evaluation error should be thrown to indicate the issue to the user.

Tasks:

• [ ] Implement a @validate directive that developers can use on custom scalars.
• [ ] @validate accepts a js function as input.
• [ ] errors should follow the formatting guidelines of Tailcall Evaluation Errors

Example

scalar EvenNumber @validate(js: "isEven")

function isEven(num) {
	return num % 2 === 0
}

[tusharmath]

/bounty 100

[algora-pbc[bot]]

~~## 💎 $100 bounty • Tailcall Inc.~~

~~### Steps to solve:~~ ~~1. Start working: Comment /attempt #1847 with your implementation plan~~ ~~2. Submit work: Create a pull request including /claim #1847 in the PR body to claim the bounty~~ ~~3. Receive payment: 100% of the bounty is received 2-5 days post-reward. Make sure you are eligible for payouts~~

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Attempt	Started (GMT+0)	Solution
🔴 @webbdays	May 4, 2024, 9:22:15 AM	WIP
🔴 @mobley-trent	May 7, 2024, 2:39:49 PM	WIP
🔴 @beelchester	Aug 6, 2024, 3:01:42 AM	WIP

[webbdays]

/attempt

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[algora-pbc[bot]]

@webbdays: Reminder that in 1 days the bounty will become up for grabs, so please submit a pull request before then 🙏

[algora-pbc[bot]]

The bounty is up for grabs! Everyone is welcome to /attempt #1847 🙌

[mobley-trent]

/attempt #1847

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[algora-pbc[bot]]

💡 @mobley-trent submitted a pull request that claims the bounty. You can visit your bounty board to reward.

[webbdays]

@mobley-trent are you still on this?

[mobley-trent]

Feel free to pick up the issue @webbdays

[github-actions[bot]]

Action required: Issue inactive for 30 days. Status update or closure in 7 days.

[beelchester]

/attempt #1847

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@beelchester	8 tailcallhq bounties	Rust, TypeScript, Go & more		Cancel attempt

[algora-pbc[bot]]

@beelchester: Reminder that in 1 days the bounty will become up for grabs, so please submit a pull request before then 🙏

[algora-pbc[bot]]

The bounty is up for grabs! Everyone is welcome to /attempt #1847 🙌

[github-actions[bot]]

Action required: Issue inactive for 30 days. Status update or closure in 7 days.

[github-actions[bot]]

Issue closed after 7 days of inactivity.