Inserting DataFlow Expressions

A number of Expression Builder dialogs are provided for generating expressions ( Expression Language) for use with operators such as Filter Rows, Derive Fields, and Group. The expressions you generate with these dialogs can be inserted directly into your RushScript source file.

Select the location in your source file where you would like to insert an expression. This would generally be within the arguments to dr.filterRows (the predicate argument), dr.deriveFields (the derivedFields argument), dr.group (the aggregations argument), etc.

There are three types of expressions you can build. Select the appropriate expression builder depending on the operator you are using:

Expression Builder	Type of Expression Returned	Associated Operators
Insert Function Expression	A single scalar valued function.	Using the AssertPredicate Operator to Assert a Predicate Condition, Using the FilterExistingRows Operator to Filter by Data Set Membership, Using the FilterRows Operator to Filter by Predicate, Using the Join Operator to Do Standard Relational Joins
Insert Field Derivation Expression	One or more scalar valued functions, each assigned to an output field.	Using the DataQualityAnalyzer Operator to Analyze Data Quality, Using the DeriveFields Operator to Compute New Fields
Insert Aggregation Expression	One or more aggregations, each optionally assigned to an output field.	Using the Group Operator to Compute Aggregations, Using the RowsToColumns Operator to Convert Rows to Columns (Pivot)

When you are using a supported editor, these options can be found on the toolbar, by right-clicking in the editor’s text area, or under the Edit menu. Supported editors include:

• Eclipse JavaScript Editor (part of the Eclipse JavaScript Development Tools plugin)

You will be presented with the Using the Expression Builder dialog, with options appropriate for the type of expression you are building. After you have finished building your expression, click Insert to add it to your RushScript source file.

If you would like to edit an existing expression, you can select the entire expression within your source file, and then open the appropriate Expression Builder dialog.