What is a Lookup?

Lookups are denoted by a dotted double-ended connector transferring data into and out of a   View Action, and are used to lookup and retrieve records in other recordsets. Lookup views require:

• Incoming Mappings: the attributes being passed into the View Action via the lookup connector
• Output Attributes: the attributes being used by View Action to filter results
• Outgoing Mappings: the attributes being passed out of the View Action via the lookup connector 

Creating Lookups

1. Hover over an Action node, e.g. a Calculate Action, on the canvas and select 
2. Enter a name for the Lookup Connector
3. Click onto a   View Action on the canvas
4. Alternatively, click onto any empty space on the canvas to create a new   View Action

Worked Example

Here's a worked example using the School Data (available from the Learning Centre).

In this example, we will configure an Actionflow that retrieves the Student IDs of students attending a course, and outputs these to a string field. We will set up a background filter that uses the string field to filter a grid of Students.

In this example, we are using a Course Management screen - the screen was created using the Tile with Buttons template, and contains:

• a grid of the School Courses data
• a grid of the School Students data
• a string field

Lookup to Retrieve Data

We will create an Actionflow containing a  Calculate Action and a   View Action. The Calculate Action will allow the input data to pass through into the View Action, where it will be used to lookup to the Course Attendees table to find the students attending the courses. 

To do this it we will:

• Lookup using the Course ID, which is found on both the Course and Attendees tables
• Use the Course ID on the Attendees table to find the corresponding Student ID(s) of the student(s) attending that course
• Write those Student ID(s) back to the screen onto a field
• Setup a background filter to only show students in a Students grid that match the Student ID in the field

Create Calculate Action and View Action

1. Add a custom button from the palette to the Tile - Footer area beneath the School Courses grid
   1. Name: Enrolled Students
2. Right-click on the button and choose  Add Actionflow
3. Enter a name for the Actionflow,
   1. Name: Find Students
   2. Select Confirm
4. Select Click to Connect and for the input, choose the School Course  Grid data source, then select Connect Input
5. In the Mappings window that opens, drag the CourseID attribute from the left to the right
   1. Select Save
6. Click and drag the  Calculate icon from the toolbar onto the canvas
7. In the Create Calculate Action window enter:
   1. Name: FindStudents

   2. Select Create Action

      The Calculate Action will be configured below as it is needed for the output. For the input data, the attributes pass through without being processed.

8. Click and drag the  icon onto the  Calculate action node
9. Right-click on the in connector and choose  Open Mappings
   1. Drag the CourseID attribute on the left onto the Drag and Drop area on the right
   2. Select Save
10. To lookup to the Course Attendees table, we need to create a   View Action
11. Click and drag the   View icon from the toolbar onto the canvas
12. In the Create View Action window enter:
    1. Name: GetStudentID
    2. Primary Table: choose Course Attendees

    3. Select Create Action

Configure the Lookup on the View Action 

1. Hover over the  Calculate Action and select 
2. Enter a name for the Lookup Connector:
   1. Name: lu
   2. Select Confirm
   3. When the red arrow shows, click on the   ViewAction on the canvas
3. Select the   View Action on the canvas to open its  Properties
4. In the Output Attributes section, click on the  icon 
   1. In the Available Attributes window, drag StudentID into the Output Attributes section of the  Properties
   2. Click OK
5. Select the lu connector to map the incoming and outgoing data
6. For the Incoming Mappings:
   1. Drag the CourseID attribute from the left (Calculate Action) into the Drag and Drop area on the right to create a corresponding attribute in the   View Action
   2. Select Next
7. For the Outgoing Mappings:
   1. Drag the StudentID attribute from the left (View Action) to the Drag and Drop area on the right to create a corresponding attribute back to the  Calculate Action
   2. Right-click on the StudentID attribute you just created and rename it
      1. 
   3. Click Confirm
8. We need to filter the data coming out of the lookup 
9. Click on the   View Action to open its Properties
10. In the Data Retrieval Options section, click the  icon next to Filter
    1. Name: ByCourseID
    2. Filter Details: 
    3.  Apply and Close the Filter tab
11.  Apply the View Action tab

Configure the Calculate Action and Output

1. Click on the  Calculate Action on the canvas to open its Properties
2. In the Output Attributes section, click the  icon to create a new attribute:
   1. Name: CourseStudentIDs
   2. Type: Choose Structured Data 
      1. This will return the results as an array

   3. Expression: 

      lu.StudentIDFound

   4. Click  Apply and Close

3. Under Connections, select  Add
4. Add an Output Connection Point:
   1. Name: out
   2. Click Create Connection Point
5. Select Click to Connect and choose the  Form data source, then Connect Output
   1. Close the Mappings window that opens
6. Hover your mouse over the Calculate Action on the canvas and click out
7. When the red arrow shows, click on the  node under Connections
8. On the Mappings window, drag across the CourseStudentIDs output attribute from the Calculate Action into the Drag and Drop area on the right to create a corresponding attribute in the output
   1. Click Save
9. Click the out connection point, under Connections
10. On the Mappings window, drag the CourseStudentIDs output attribute from the output to the string field, StudentIDFromAttendees
    1. Click Save
11. The Actionflow is now built

Setup Background Filter

The Actionflow will populate the string field, StudentIDFromAttendee, but the values in this field need to be linked to the Students grid using a background filter in order to only see the students for the selected course.

1. Return to the screen containing the School Courses grid

2. Right-click on the Students grid and choose 

    Show the View Configuration
3. In the Data Retrieval Options, next to Background Filter, click 
   1. Name: ByStudentID
   2. Filter Details: 
   3. Click  Apply and Close
4.  Lock the screen and press the Enrolled Students button to see the Actionflow working

1.17 Instances and Reusability