Filter Actions (accept, reject)

Filter actions decide whether a record (an order, a line item, a return, a shipment) continues through DropStream’s processing or gets stopped. There are four:

• accept — let it continue.
• reject — stop it from continuing.
• default accept — accept anything no other rule decided on.
• default reject — reject anything no other rule decided on.

By default, every record is accepted. You only need filter actions when you want to stop something or set a non-default fallback.

reject

when
  order.shipping_address.country is "MX"
then
  reject order
end

Rejected records don’t move forward. For an order, that means it doesn’t go to the warehouse. For a line item, that means the item is removed from the order. The order itself continues with whatever items remain.

for order_lines in order
  when order_line.custom.is_restricted then
    reject order_line
  end
end

accept

The default for everything is accept. Writing accept order explicitly is rarely necessary — but it’s useful as the match in a series of when blocks where rejection is the fallback:

for order_lines in order
  when order_line.qty_ordered - order_line.qty_fulfilled >= order_line.qty_ordered then
    accept order_line
  end
end

default reject order_line

Read this as: for each line, if there’s enough inventory, accept it. Anything we didn’t accept, reject by default.

default accept and default reject

A default filter action applies to every record the rule didn’t explicitly decide on. Use it as a fallback at the end of the rule.

rule "Allow only US and Canadian shipments"
  when
    order.shipping_address.country is "US"
    or order.shipping_address.country is "CA"
  then
    accept order
  end

  default reject order
end

The when block accepts US and Canadian orders. The default reject at the end catches everything else — Mexico, UK, etc.

A default doesn’t go inside a when — it’s a top-level statement, typically the last line before the closing end.

How the four interact

For a given record, the most specific decision wins:

1. An explicit accept or reject always overrides a default.
2. If multiple when blocks both fire, the last one wins. So put more-specific rules later.
3. If no accept/reject fires and no default is set, the record is accepted.

What you can filter

• Orders — accept order, reject order. Rejecting an order stops it from going to the warehouse.
• Line items — accept order_line, reject order_line. Rejected items are removed from the order; the order itself continues.
• Other models in their respective hooks — e.g. reject sales_order_return_item in a Return Import hook.

Common patterns

Whitelist by country:

when order.shipping_address.country is "US" then accept order end
default reject order

Reject anything restricted:

for order_lines in order
  when order_line.custom.is_restricted then reject order_line end
end

Reject by SKU pattern:

for order_lines in order
  when order_line.sku starts_with "BANNED-" then reject order_line end
end

Inventory-aware filtering:

for order_lines in order
  for inventories in order_line
    when
      inventory.available >= order_line.qty_ordered
      and inventory.warehouse_id is "PRIMARY"
    then
      accept order_line
    end
  end
end

default reject order_line

For each line, look at each inventory record. If there’s enough at the primary warehouse, accept. Otherwise, the default reject kicks in.

Tips

• Test with the trace harness. A reject that fires when you didn’t expect — or doesn’t fire when you did — is best diagnosed in the trace, where you can see exactly which conditions evaluated to what.
• default after, not before. A default doesn’t apply retroactively — but ordering still matters for readability.
• Reject on a line item doesn’t reject the order. A line being rejected shrinks the order; the order itself continues unless explicitly rejected.