Does batch method run its statements in order?

[cervonwong]

In a batch I have

await batch((batch) {
  batch.insertAll(
    employeeTypes,
    [...],
  );
  batch.insertAll(
    employee,
    [...],
  );
});

When inserting each Employee into the employee table, they have a foreign key constraint on the id of the employeeTypes table. Can I be sure that all employeeTypes will be inserted before employees are inserted, or do I have to create a new batch?

Also, within a single batch.insertAll(), can I be sure that the EmployeeTypes are inserted in the order provided by the list (so that the autogenerated IDs can be predicted)?

Thanks! (First discussion!)

[simolus3]

Hi,

the order was undefined in older moor versions, but we now guarantee that batches run statements in the order in which they were issued (and we have tests for that!). This is also true for each row inside an insertAll call.
I don't know the exact moor version where this was changed, but if you're on 3.4.0 you should be safe.

(so that the autogenerated IDs can be predicted)

Note that, if you do

final id = await currentAutoGeneratedId();
final batch = await batch(() {
  // assume that rows start at id
});

There could be some interleaving between await currentAutoGeneratedId() and await batch() if you run another insert concurrently. If you want to be safe, wrap the select and the batch in another transaction block.