You can use an expression parameter in the following transformation fields:

Aggregator. Port expression.
Expression. Port expression.
Filter. Filter condition.
Join. Join condition.
Lookup. Lookup condition.
Rank. Port expression.

If you configure an expression parameter in a filter, join, or lookup condition in a Filter, Join, or Lookup transformation, the expression parameter must evaluate to TRUE or FALSE.

If you configure an expression parameter in the port expression for an Aggregator, Expression, or Rank transformation, the port must contain only the expression parameter. The result value of the parameter must match the port data type. For example, if the port data type is a string, the expression must evaluate to a string.

Define the expression parameter in the Expression Editor. Select

Specify by Parameter

to indicate that the complete expression is parameterized.

For example, the following image shows the

Specify by Parameter

option for the filter condition:

When you use an expression parameter, you can create the expression parameter or you can select an existing expression parameter to use in the transformation. An expression parameter can contain ports, operators, and constants. For example, you might create expression parameters with different port names and operators in a dynamic mapping. The expression parameter cannot contain other parameters.

If the expression parameter is a transformation parameter, you can bind the transformation parameter to a mapping parameter. You can override the mapping parameter at run time.