Function write_update 

pub async fn write_update<R: Resource>(
    cx: &Cx,
    record: R::Model,
    posted: Posted<R::Form>,
    ex: &mut dyn Executor,
) -> Result<R::Model, WriteError<<R::Form as RecordForm>::Field>>

The derived update: assign every named field and execute through ex, then link the record to the records each named many-to-many field holds, and unlink it from the others.

A submission that names no field writes nothing. The instance update reloads record, so the returned row is the written one.

Errors

WriteError::Failed with the driver’s error.