Difference between revisions of "Require Columns"

From PresenceWiki
Jump to: navigation, search
 
Line 12: Line 12:
  
 
Because you are manually typing in the column name it is of course extremely important that your column name exactly matches the column in the initiating task.  If you specify a column name that does not exist in the data, the column will be created anyway but with all NULL values.
 
Because you are manually typing in the column name it is of course extremely important that your column name exactly matches the column in the initiating task.  If you specify a column name that does not exist in the data, the column will be created anyway but with all NULL values.
 +
 +
{{DataTableNodes}}

Revision as of 10:32, 23 June 2010

Presence Tasks can be cascaded or nested from one to another. To make it easier to access data on the Presence Context between nested processes we can specify which columns are required or will be used from the parent task.

Note that adding a required column only allows you to access the virtual column from the Presence Context without the column actually being created there by means of a query. It is not required in order for the Presence Server to correctly pass data between tasks at run time - that occurs automatically.

Drop a Require Column(s) node onto a task; the following dialog is displayed.

insert pic

Click the New button (bottom left). The Enter Column Name(s) dialog appears. Enter the name of the column you wish to reference from your initiating process. You do not need to specify the :var{}, just the column name.

Specify the Data Type of the column. This again aids visibility in the Presence Context.

Because you are manually typing in the column name it is of course extremely important that your column name exactly matches the column in the initiating task. If you specify a column name that does not exist in the data, the column will be created anyway but with all NULL values.


Data Filter | Require Columns | Append Data Column | Multiple Column Appender

Drop Column | Drop Row(s) | Calculate Column Aggregate | Dataset Splitter | Merge Data

Create Data Table | Clear Data Table | Sort Data Table | Drop Duplicate Rows | Store Data Table | Retrieve Data Table


Task Elements > Data Table Nodes > Require Columns