Struct BeforeMutationRequest 

#[non_exhaustive]
pub struct BeforeMutationRequest<'a> {
    pub principal: Option<&'a SecurityContext>,
    pub mutation: &'a str,
    pub response_key: &'a str,
    pub arguments: &'a Value,
    pub reader: Option<Arc<dyn GuestQueryBridge>>,
}

The write a BeforeMutationGate is being asked to adjudicate.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

principal: Option<&'a SecurityContext>

The authenticated principal, or None for an unauthenticated (anonymous) request.

mutation: &'a str

The mutation field name — the key the chain is looked up under. Never the response alias.

response_key: &'a str

The key this root’s result appears under in data (the alias when the document supplies one, otherwise the same as mutation). Diagnostics only.

arguments: &'a Value

The arguments this write will run with: request variables merged with the root field’s inline literals, nested $var references resolved. Null when the write has no arguments at all.

reader: Option<Arc<dyn GuestQueryBridge>>

The caller-scoped, read-only GraphQL bridge this hook may read through (#1328), or None on a request built by hand.

Owned rather than borrowed because the gate hands it to guest code that runs on another thread — the Deno runtime spawns an OS thread per invocation — so it has to outlive this call. The engine builds one per adjudicated write; a gate that never reads simply drops it.

Implementations

impl<'a> BeforeMutationRequest<'a>

pub const fn new( principal: Option<&'a SecurityContext>, mutation: &'a str, response_key: &'a str, arguments: &'a Value, ) -> Self

Build a request with no read bridge. The engine is the only production constructor; this exists so an implementor outside this crate can exercise its own gate, which #[non_exhaustive] would otherwise make impossible.

pub fn with_reader(self, reader: Arc<dyn GuestQueryBridge>) -> Self

Attach the caller-scoped read bridge (#1328).