Struct BeforeMutationChain 

pub struct BeforeMutationChain {
    pub triggers: Vec<BeforeMutationTrigger>,
}

Chain of before-mutation triggers for a single mutation.

Executes multiple before:mutation triggers in declaration order. Each trigger can modify the input and pass it to the next trigger, or abort the mutation by returning an error.

Execution Semantics

• Synchronous: blocks the mutation (execution is on the hot path)
• Sequential: triggers execute in declaration order
• Propagating: each trigger receives the modified input from previous trigger
• Short-circuit: first abort stops the chain immediately
• Default timeout: 500ms per trigger (shorter than general 5s default)
• Side-effects: any side-effects from aborted triggers are NOT rolled back

Example

let chain = BeforeMutationChain {
    triggers: vec![
        validateInput,  // checks required fields
        checkDuplicates, // checks uniqueness
        auditLog,       // logs the attempt
    ]
};

let result = chain.execute(input, &observer).await?;
match result {
    Proceed(modified) => { /* mutation continues */ }
    Abort(error) => { /* mutation cancelled */ }
}

Fields

triggers: Vec<BeforeMutationTrigger>

Triggers in declaration order.

Implementations

impl BeforeMutationChain

pub async fn execute<H>( &self, input: Value, modules: &HashMap<String, FunctionModule>, observer: &FunctionObserver, host: &H, limits: ResourceLimits, ) -> Result<BeforeMutationResult>

where H: HostContext + ?Sized,

Execute the before-mutation chain with the given input.

Runs all triggers in declaration order. Each trigger receives the (possibly modified) output of the previous trigger as its input. The first Abort short-circuits the chain.

Convention for function return values

Functions signal their intent via the returned JSON object:

• {"abort": "message"} → abort the mutation with message
• {"input": {...}} → proceed with modified input
• Any other value (or null) → proceed with the input unchanged

Errors

Returns Err if a trigger’s function name is not found in modules, or if function execution itself returns an error.

Trait Implementations

impl Clone for BeforeMutationChain

fn clone(&self) -> BeforeMutationChain

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BeforeMutationChain

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.