Setting Values

The set action assigns a value to a field. It’s the most common action in BGL.

set order.shipping_carrier_name to "UPS"

The pattern is set <target> to <expression>. The target is what you’re changing; the expression is the value to put there.

What you can set

• A field on the model: set order.notes to "..." or set order_line.sku to "..."
• A nested field: set order.shipping_address.country to "US"
• A custom field: set order.custom.tier to "gold"
• A session variable: set $total to 0.0 (see Variables)

What you can set to

The right-hand side of set ... to ... is any BGL expression. That includes:

Literals:

set order.shipping_carrier_name to "UPS"
set order.shipping_amount to 0.0
set order.custom.is_gift to true
set order.custom.scheduled_for to @tomorrow

Other fields:

set order.billing_address.country to order.shipping_address.country
set order_line.unit_cost to order_line.unit_price

Math:

set order.tax_amount to order.subtotal * 0.08
set order.shipping_amount to order.subtotal * 0.05

String concatenation (with &):

set order.notes to "Customer: " & order.customer_email
set order.custom.recipient_name to order.shipping_address.first_name & " " & order.shipping_address.last_name

Type-cast values:

set order.custom.priority to order.custom.priority_text as number
set order.notes to order_line.qty_ordered as text & " items"

See Data Types for casting and Strings and Regex for string operations.

Clearing a value

To clear a field, set it to blank:

set order.shipping_amount to blank
set order.notes to blank

blank is BGL’s way of saying no value (null). The same keyword works for any field type.

Setting based on a condition

Wrap a set in a when block to apply it conditionally:

when
  order.subtotal > 500.0
then
  set order.custom.tier to "gold"
end

For if-this-then-A-else-B logic, use two when blocks — BGL doesn’t have an inline conditional operator:

when
  order.subtotal > 100.0
then
  set order.custom.tier to "premium"
end

when
  order.subtotal <= 100.0
then
  set order.custom.tier to "standard"
end

(Or simpler: set a default first, then override.)

set order.custom.tier to "standard"

when
  order.subtotal > 100.0
then
  set order.custom.tier to "premium"
end

The second block runs after the first, so the override wins when the condition matches.

Setting collection items

Inside a for loop, you can set fields on each iterated item:

for order_lines in order
  set order_line.custom.processed to true
end

See Loops for the iteration syntax.

Setting in nested actions

Some actions create new items, and the set calls inside configure that new item:

add 1 item to order_lines in order
  set item.sku to "GIFT-WRAP"
  set item.unit_price to 0.0
end

Here item refers to the item being added. See the Action Reference for add, accumulate, and other actions that work this way.

Limitations to know about

BGL doesn’t have built-in functions for common transformations. There’s no trim, uppercase, substring, abs, round, min, max, etc. To do those things you’ll need:

• String manipulation — use regex via replace /.../ with "..." in field. See Strings and Regex.
• Math — use arithmetic operators. For things like absolute value or rounding, work it out with conditional sets.

If you find yourself wanting a function that doesn’t exist, the workaround is usually a session variable populated by when blocks. See Variables.