OpenEdge Development:<br />ProDataSets Using Data-Source attributes and methods

You can identify the DATA-SOURCE currently attached to a buffer using this attribute:

Syntax
`buffer-handle`:DATA-SOURCE

The GET-DATASET-BUFFER attribute on the Data-Source handle returns the buffer handle for the Data-Source’s associated ProDataSet buffer:

Syntax
`buffer-handle` = `datasource-handle`:GET-DATASET-BUFFER.

The DATA-SOURCE-COMPLETE-MAP attribute returns a comma-separated list of field name pairs for all fields in a ProDataSet temp-table buffer that are mapped to corresponding fields in an attached Data-source object. This list is formatted as a comma-separated list of field name pairs, qualified with the ProDataSet and Data-Source temp-table names, using the following syntax:


`tt-buffer-name`.`tt-field-name`,`db-table-name`.`db-field-name` [, ...]

If the ProDataSet temp-table buffer does not have an attached Data-source object, this attributes returns the Unknown value (?).

You can get the source buffers from a data-source with the NUM-SOURCE-BUFFERS attribute and the GET-SOURCE-BUFFER method, as shown:

Syntax
`datasource-handle`:NUM-SOURCE-BUFFERS `datasource-handle`:GET-SOURCE-BUFFER [ (`buffer-index`) ]

Because a Data-Source most often has only one source buffer, the buffer-index argument is optional and defaults to 1.

You can get a comma-separated list of key fields defined in an associated KEYS clause for the specified buffer by using the KEYS attribute, as shown:

Syntax
`data-source-handle`:KEYS( `buffer-sequence-number` )

If there are no defined key fields, this attribute returns a comma-separated list of key fields in the buffer’s unique primary index (if any). If there are no defined key fields and no unique primary index, this attribute returns the string "ROWID”.

You can retrieve the ROWID of the data source row at which the next FILL operation should start with the NEXT-ROWID attribute, as shown:

Syntax
`data-source-handle`:NEXT-ROWID( `buffer-sequence-number` \| `buffer-name` )

Progress sets this attribute after each FILL operation in a series of FILL operations to retrieve data source rows in batches. You typically assign the value of this attribute to the RESTART-ROWID attribute before each FILL operation.

You can retrieve the ROWID of the data source row at which a FILL operation will start with the RESTART-ROWID attribute. Set this attribute before each FILL operation in a series of FILL operations to retrieve data source rows in batches. For example

Syntax
`data-source-handle`:RESTART-ROWID( `buffer-sequence-number` \| `buffer-name` )

You can retrieve the current where-clause for a buffer’s query, whether it has been set explicitly or derived automatically from the fields in its relation, using the read-only FILL-WHERE-STRING attribute, as shown:

Syntax
`datasource-handle`:FILL-WHERE-STRING

You cannot set this attribute, but you might want to use the string to help you construct a query of your own to retrieve records that perhaps require more filtering than the relation provides by default.

As with other objects, you can get a handle to a static Data-Source. Precede the Data-Source name with the keyword DATA-SOURCE, as shown:

Syntax
[ `handle-var` = ] DATA-SOURCE `data-source-name`:HANDLE

This block of code added to DynamicDataSet2.p retrieves the Data-Source for each of the ProDataSet’s buffers and displays its database source buffer’s name and the where-clause that Progress generates automatically for the table based on the relation:

DO iEntry = 1 TO phDataSet:NUM-BUFFERS: hBuffer = phDataSet:GET-BUFFER-HANDLE(iEntry). `MESSAGE "Data-Source: "` `hBuffer:DATA-SOURCE:GET-SOURCE-BUFFER:NAME SKIP` `"WHERE-STRING:" hBuffer:DATA-SOURCE:FILL-WHERE-STRING` `VIEW-AS ALERT-BOX.` DELETE OBJECT hBuffer:DATA-SOURCE. END.

DO iEntry = 1 TO phDataSet:NUM-BUFFERS: 
   hBuffer = phDataSet:GET-BUFFER-HANDLE(iEntry). 
   MESSAGE "Data-Source: " 
      hBuffer:DATA-SOURCE:GET-SOURCE-BUFFER:NAME SKIP 
      "WHERE-STRING:" hBuffer:DATA-SOURCE:FILL-WHERE-STRING 
      VIEW-AS ALERT-BOX. 
   DELETE OBJECT hBuffer:DATA-SOURCE. 
END.

The first database table for the ProDataSet is the Customer table. There’s no default where-clause for it because it’s the top-level table and has no parent. Even though you have defined a where-clause for this top-level table in the DynamicDataSet procedure, that’s not assigned to the FILL-WHERE-STRING attribute. This attribute shows only the default selection Progress generates for you:

The second Data-Source is the Order table. It does have a FILL-WHERE-STRING because it is the child of a relation. If you compare its FILL-WHERE-STRING attribute with the WHERE-STRING of its Data-Relation, you can see the difference between the job the Data-Source has to do during a FILL and the job the relation does after the FILL is complete and you’re navigating the ProDataSet.

This FILL-WHERE-STRING retrieves Order records from the Order database table by matching the CustNum of the ttCustomer temp-table record that has just been retrieved from the database Customer table and created in the ProDataSet’s temp-table.

The relation’s WHERE-STRING compares the ttCustomer temp-table with the records already in the ttOrder temp-table, because it’s used to navigate the filled ProDataSet:

Finally, you see the Data-Source for the SalesRep table. It also has no FILL-WHERE-STRING because it is not involved in a relation at all.

Standard object attributes that are valid for the Data-Source and accessible through its handle include:

ADM-DATA

HANDLE

INSTANTIATING-PROCEDURE

NAME

NEXT-SIBLING

PRIVATE-DATA

TYPE