Mappings

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Step 3. Create a Filter transformation

In the following procedure, you create a Filter transformation to filter accounts based on the state in which each account is located. You also create a parameter to hold state values.

You want this mapping to run tasks that filter accounts based on specific states. To accomplish this, you add a Filter transformation to the data flow to capture state information. You then define a parameter in the filter condition to hold the state value. When you use a parameter, you can reuse the same mapping to create multiple tasks. You can specify a different state value for each task. Or you can use the same

mapping

task and change the value for state when you run the task.

The sample Account source file includes a State field. When you use the State field in the filter condition, you can write data to the target based on the state. For example, when you use State = MD as the condition, you include accounts based in Maryland in the data flow. When you use a parameter for the value of the filter condition, you can define the state that you want to use when you run the task.

Field rules define the fields that enter the transformation and how they are named. By default, all available fields are included in the transformation. You might want to exclude unnecessary fields when you have large source files. Or you might want to change the names of certain incoming fields, for example, when you have multiple sources in a mapping. Field rules are configured on the

Incoming Fields

tab. For this tutorial, do not configure field rules.

To add a Filter transformation, drag a Filter transformation from the Transformation palette to the mapping canvas and drop it between the src_FF_Account Source transformation and the NewTarget transformation.

You might need to scroll through the Transformation palette to find the Filter transformation.

When you drop a new transformation in between two transformations in the canvas, the new transformation is automatically linked in the data flow, as shown in the following image:

The Source, Filter, and Target transformations display in a row in the mapping canvas with lines between the transformations, which illustrates that the transformations are connected in the data flow.

When you link transformations, the downstream transformation inherits fields from the previous transformation.

To configure the Filter transformation, select the Filter transformation on the mapping canvas.

To name the Filter transformation, in the Properties panel, click

General

and enter

flt_Filter_by_State

for the Filter transformation name.

To create a simple filter with a parameter for the value, click

Filter

. For the

Filter Condition

, select

Simple

Click

Add New Filter Condition

, as shown in the following image:

When you click

Add New Filter Condition

, a new row is created where you specify values for the new filter condition.

For

Field Name

, select

State

For

Operator

, select

Equals

To parameterize the filter condition value, for

Value

, select

New Parameter

In the

New Parameter

dialog box, configure the following options:

Filter Condition Detail	Description
Name	Name of the filter condition. Enter p_FilterConditionValue for the name.
Display Label	Label that shows in the mapping task wizard where you enter the condition value. Enter Filter Value for State for the label.
Description	Description that appears in the mapping task wizard. Enter this text for the description: Enter the two-character state name for the data you want to use.
Type	Datatype of the field used for the filter condition. The State field is a String datatype, which is already specified in the dialog box.
Default Value	Default value for the filter condition. The mapping task uses this value unless you specify a different value. You want to run the task for accounts in Maryland by default, so enter MD .