An Eclipse Modeling Framework (EMF) data set is a database in table
format whose rows and columns are mapped from an EMF data source. The data
set is formatted so that you can use Business Intelligence and Reporting Tools
(BIRT) to generate reports from it.
The data source that you use must exist before you start this task.
To create a new data source, see the related task named "Creating EMF data
sources."
- Open the Report Explorer view. Click .
- In the Report Explorer view, right-click a report design; then
click Open.
- Open the Data Explorer view. Click .
- In the Data Explorer view, right-click Data Sets;
then click New Data Set.
If you want
to join data from multiple tables, you can also click New Joint
Data Set. For additional information, see the topic "How to join
data sets" in the Field Guide to BIRT.
- Type a name for the data set, select EMF Data Set as the
type, select a data source, and click Next.
- On the Query Parameters page, list all the
query parameters that you need to define queries in the data set; then click Next. Use this page to add, remove, reorder, and rename parameters. Parameters
on this page are identified by the internal name of the parameter. The internal
name is the name that you use in XPath expressions, so it must conform to
XPath naming conventions for variables; it must start with a letter or underscore
(_), and can contain any sequence of letters, digits, or underscore characters.
Changes that you make on this page also appear on the Parameters page;
see step 10.
Parameters are a flexible and powerful tool that
allow you to include many special types of information in reports. For information
about how you can use parameters, see the related concept named "Parameters
in EMF and UML data sets."
Note: After you define a parameter, you can
refer to it in both row-mapping and column-mapping queries by using its internal
name preceded by a dollar sign ($).
- Define the row mapping for the data set. You define
a collection of elements that form the rows of a table and that specify the
element types. To define the row mapping, complete the following steps:
- Browse to select one of the models specified in the data source
that you are using.
- To define the row mapping, specify an XPath expression. For example, to map all classes in the model, the expression is //Class and
the type is Class.
Note: When you write row-mapping XPath
expressions, remember that root is the resource instance. For more information
about XPath syntax, see the related links at the end of this topic.
You
can type the expression directly, or build it from elements in the EMF structure,
which you add to the Expression field by selecting
a node in the EMF structure and then clicking the right arrow (>) button.
- If the expression starts from a parameter as a context, and
not from the root of the resource, you can deselect the check box for Evaluate
for every data source instance model. This can improve
performance, because the expression does not need to run for every resource.
- Select an element in the EMF structure that has the type required
for the XPath expression; then click the right arrow (>) button for the Type field. For example, for //Class, the result type is Class.
- Click Next.
- Define the table columns for your data set. For column-defining
XPath expressions, root is an object of the type that you specified for the
return type in the previous step. You can define columns either by typing
the values for them directly in the matrix or by completing the following
steps:
- Click Browse to display a type to browse.
- Select an entry in the tree to use as a table column and click
the right arrow (>) button.
- Specify all the columns that you need. You can delete columns,
or change their order, by clicking the buttons to the right of the Column
Mapping matrix.
- Adjust the values for Query and Type for each column as necessary.
- After you configure the table, click Finish. The Edit Data Set window opens.
- If the data set includes parameters, use the Parameters page
of the Edit Data Set window to complete the definition
of the parameters. Specify the display name, which is initially set to the
internal name; the type, which is initially set to String;
the direction, which is initially set to Input; and the name
of the report parameter, if any, to bind to the data set parameter. When you bind values to a data set parameter on the Property
Binding page, you use the parameter display name.
- You can continue to edit, click Preview Results to
check your work, or click OK to close the window.
Note: To modify your data set at any time, in the Data Explorer view,
right-click the data set; then click Edit.
You can now use the BIRT feature to complete the report design, incorporating
elements from the data set. For information, see the Field Guide to BIRT.