Adding an Operator

Add an operator such as Select, Join, Order By, or Aggregate to a view model. Operators specify how your view model transforms and integrates data.

Prerequisites

Before starting this procedure, create a view model and add at least one Input Source element.

When you add an operator to the data flow in a view model, you must connect it to other elements for appropriate inputs and outputs; what these other elements are depends on the operator and on the task your view model is performing. Most operators require at least one input and one output. You can’t set an operator’s properties until it’s connected to an input.

Follow these steps to create an operator and connect it to inputs (upstream) and outputs (downstream).

Click an operator in the Operators or the Advanced section of the palette (immediately to the left of the view model pane).
Click in the view model pane to create the new operator.
Note: To insert the new operator into the flow between two existing operators, click the line that connects them.
A new operator appears in the spot where you clicked.
If necessary, connect the new operator to inputs and outputs:
1. Click Connection in the palette.
2. Click the upstream element that will provide input (an Input Source element or another operator), then click the new operator. A line connecting the data source to the new operator appears in the view model.
3. Repeat for additional inputs.
4. Click Connection, the new operator, and the downstream element that will receive output (the Result element or another operator). A line connecting the new operator to the recipient of its data appears in the view model.
Enter Control S to save the view model.
Double-click the new operator to open its properties dialog.

Next

See the operator’s properties topic for information on setting its properties.

Operators in View Models
WorkSpace Data Federation provides a selection of elements and operators you can use to manipulate data in a view model.
Using Expressions and Control Variables in Operators
Many view model operators in WorkSpace Data Federation allow you to specify expressions that are evaluated at runtime to configure how your view model behaves.
Access to Columns from Incoming Result Sets
You can access values in the columns of incoming result sets from expressions that you define in an operator.
Access to Global Parameters
Global parameters defined or mapped into a view model can be referenced in the form variables.global.<globalName>. You can use the expressions menu to insert references to global parameters into your expressions.
Variables in Expressions
You often need to create variables when constructing view models, particularly as the complexity of the model grows or as you use more advanced operators such as Iterator. WorkSpace Data Federation provides a JavaScript object named variables, which lets you store any variables you wish to use across multiple operators.
Performance of Sort-Based Operators in View Models
Several operators must sort their inputs. These include Order By, Join (only when using the Sort Merge algorithm), Group By, and Intersection, as well as any operator that uses the Distinct option to eliminate duplicate rows.

Parent topic: Developing a View Model

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