feat: enable alias declarations

[Azzerty23]

This is a first attempt at implementing alias declarations. The goal is to enable code reuse for both policy rules and default functions.

Example of intended usage:

alias allowAll() {
    true
}

alias defaultTitle() {
    'Default Title'
}

alias currentUser() {
    auth().id 
}

alias ownPublishedPosts() {
    currentUser() == authorId && published
}

model Post {
    id          Int      @id @default(autoincrement())
    title       String   @default(defaultTitle())
    published   Boolean  @default(allowAll())

    author      User     @relation(fields: [authorId], references: [id])
    authorId    String   @default(auth().id)

    @@allow('read', allowAll())
    @@allow('create,update,delete', currentUser() == authorId && published)
    @@deny('all', !ownPublishedPosts())
}

model User {
    id          String    @id @default(cuid())
    name        String?
    posts       Post[]

    @@allow('all', allowAll())
}

However, during implementation, I realized that having a shared generic alias mechanism for both policy rules and default values might not be the best idea: policy rule expressions and default value expressions are not interchangeable, and it becomes tricky to handle validation rules properly.

I initially started working on rule (#1959), but got sidetracked along the way... 😅

Also, I might have done something completely off with the SDL (Langium) changes — I have zero experience in that area.

Currently, I'm generating functions from aliases inside the policy file. But I’m thinking of reverting to my original approach of inlining the expression instead, as it would make handling relations easier. For example, this:

// generated policy.ts
function allowAll(): any {
  return true;
}

function Post_read(context: QueryContext, db: CrudContract): any {
  if (allowAll()) {
    return { AND: [] };
  }
  return { OR: [] };
}

Would become something like:

// generated policy.ts
function Post_read(context: QueryContext, db: CrudContract): any {
  if (true) {
    return { AND: [] };
  }
  return { OR: [] };
}

I’m also facing scoping issues where the expression doesn't allow referencing model fields:

alias ownPublishedPosts() {
    currentUser() == authorId && published
}
// Could not resolve reference to ReferenceTarget named 'authorId'.
// Could not resolve reference to ReferenceTarget named 'published'.
// invalid operand type for "&&" operator

@ymc9, thanks a lot in advance for your help!
If this approach doesn’t make sense at all, please don’t hesitate to say so ;)

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

🪧 Tips

Chat

There are 3 ways to chat with CodeRabbit:

‼️ IMPORTANT
Auto-reply has been disabled for this repository in the CodeRabbit settings. The CodeRabbit bot will not respond to your replies unless it is explicitly tagged.

• Files and specific lines of code (under the "Files changed" tab): Tag @coderabbitai in a new review comment at the desired location with your query. Examples:
  • @coderabbitai explain this code block.
  • @coderabbitai modularize this function.
• PR comments: Tag @coderabbitai in a new PR comment to ask questions about the PR branch. For the best results, please provide a very specific query, as very limited context is provided in this mode. Examples:
  • @coderabbitai gather interesting stats about this repository and render them as a table. Additionally, render a pie chart showing the language distribution in the codebase.
  • @coderabbitai read src/utils.ts and explain its main purpose.
  • @coderabbitai read the files in the src/scheduler package and generate a class diagram using mermaid and a README in the markdown format.
  • @coderabbitai help me debug CodeRabbit configuration file.

Support

Need help? Create a ticket on our support page for assistance with any issues or questions.

Note: Be mindful of the bot's finite context window. It's strongly recommended to break down tasks such as reading entire modules into smaller chunks. For a focused discussion, use review comments to chat about specific files and their changes, instead of using the PR comments.

CodeRabbit Commands (Invoked using PR comments)

• @coderabbitai pause to pause the reviews on a PR.
• @coderabbitai resume to resume the paused reviews.
• @coderabbitai review to trigger an incremental review. This is useful when automatic reviews are disabled for the repository.
• @coderabbitai full review to do a full review from scratch and review all the files again.
• @coderabbitai summary to regenerate the summary of the PR.
• @coderabbitai generate docstrings to generate docstrings for this PR.
• @coderabbitai generate sequence diagram to generate a sequence diagram of the changes in this PR.
• @coderabbitai resolve resolve all the CodeRabbit review comments.
• @coderabbitai configuration to show the current CodeRabbit configuration for the repository.
• @coderabbitai help to get help.

Other keywords and placeholders

• Add @coderabbitai ignore anywhere in the PR description to prevent this PR from being reviewed.
• Add @coderabbitai summary to generate the high-level summary at a specific location in the PR description.
• Add @coderabbitai anywhere in the PR title to generate the title automatically.

CodeRabbit Configuration File (.coderabbit.yaml)

• You can programmatically configure CodeRabbit by adding a .coderabbit.yaml file to the root of your repository.
• Please see the configuration documentation for more information.
• If your editor has YAML language server enabled, you can add the path at the top of this file to enable auto-completion and validation: # yaml-language-server: $schema=https://coderabbit.ai/integrations/schema.v2.json

Documentation and Community

• Visit our Documentation for detailed information on how to use CodeRabbit.
• Join our Discord Community to get help, request features, and share feedback.
• Follow us on X/Twitter for updates and announcements.

[Azzerty23]

It’s conceptually more of a fragment than an alias...
Regarding my reference issue, I understand that it's not possible to include an expression inside the body of the alias —references can't be resolved statically outside the scope of a model.
And if we use a string instead of an Expression in the body of the declaration, the references won’t be resolved in the abstract syntax tree. I’m wondering if this "fragment" idea can actually be implemented.