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  1. Preface
  2. Mappings
  3. Parameters
  4. CLAIRE recommendations
  5. Data catalog discovery
  6. Visio templates

Mappings

Mappings

Partial parameterization with input parameters

Partial parameterization with input parameters

To allow users to select one of the fields based on an input parameter at run time, you can implement partial parameterization in a mapping. Use partial parameterization to create templates for incremental data loads and other solutions.
For example, if you completely parameterize the source filter, you must include a query similar to the following example:
lastmodified_date > $$myvar
To partially parameterize the filter, you can specify the field as a variable, as shown in this example:
$field$ > $$myvar
In this case, the user can select the required field in the
mapping
task.
To implement partial parameterization, you must use a database connection and a Source transformation advanced filter or a Filter, Expression, Router, or Aggregator transformation. You can create an input parameter for one of the fields so that the user can select a specific field in the
mapping
task instead of writing a complete query. "String" and "field" are the only valid types.
You can use the same parameter in all the supported transformations.
In the following example, the filter condition uses a parameter for the field name:
The example shows an advanced filter condition, "city = $PARAM_FIELD$," in which the field name is parameterized.

Rules and guidelines for partial parameterization

When you configure partial parameterization, note the following rules and guidelines:
  • If you define a field type parameter in a Source transformation advanced filter, you can reuse it in a downstream transformation like a Router, Filter, Expression, or Aggregator. You cannot directly use field type parameters in other transformations.
  • To distinguish parameters used for partial parameterization from in-out parameters (
    $$myVar
    ), represent the parameter like an expression macro, for example,
    $<Parameter_Name>$
    .
  • If you use a field type parameter in a Source transformation with multiple objects, qualify the parameter with the object name. You can either use the object name in the mapping or use a string type parameter to configure it in a
    mapping
    task.
  • You cannot pass values for partial parameterization through a parameter file.
  • You cannot use a user-defined function in an expression that uses partial parameterization. For example, the following expression is not valid:
    concat($Field$,:UDF.RemoveSpaces(NAME))