Connecting to Data Overview
The topics in this section describe how to connect Telerik Reports to a data source, as well as how to filter, order, and group the data. Last but not least, you can also check how to create expressions that when evaluated at runtime will customize the content and appearance of your reports.
Data Source Components
- Data Source components are used to connect data items to different types of data without writing any code.
- Most of the Data Source components allow working with data source parameters which are used to filter the data on retrieval. Data source parameters can be mapped to report parameters, data fields, or the result of the expression.
- Data source components allow adding calculated fields to create new values that do not exist in the data source.
For more details see topics in Data Source Components section.
Data Items
- Data items are used to visualize the data in reports.
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The data can be:
The most straightforward approach for connecting a data item to data is to set the data item's DataSource property to a Data Source component.
- In master-detail scenarios, the data item can be connected to the parent's data as well.
For more details see topics in Data Items section.
Starting with R3 2019 (13.2.19.918), when two or more data items use the same DataSource component, the raw data is reused between them. For example, if a Table and a Graph use the same SqlDataSource, the data will be fetched just once from the database when rendering the report.
Expressions
- Expressions are widely used while designing reports to manipulate the report's data, style, and behavior. When the report runs, the report processor evaluates the expressions using a built-in scripting language and substitutes the property values where expressions were used with the result of the expression.
- There are built-in functions that allow to perform complex calculations in expressions. Users confident with any of the.NET languages can extend the expression engine to use custom functions in their reports.
- Examples of expression usage: grouping, sorting, filtering operations, properties of the report and report items(sections), bindings, conditional formatting, report parameters, etc.
For more details see topics in Expressions section.
Report Parameters
- The most common usage of report parameters is in the data-retrieval method which is one of the ways to improve the report's performance.
- Referencing report parameters inside expressions can be achieved with Parameters global object which at runtime will be replaced with the actual value of the report parameter.
- Examples of report parameters usage: in properties of the report or report items(sections), grouping, sorting, filtering operations, etc.
For more details see topics in Report Parameters section.
The optimization for reusing the raw data from the same DataSource component is valid only for data items. It doesn't concern the Report Parameters with AvailableValues relying on DataSource components. Even if several parameters fetch their AvailableValues from the same DataSource, the latter will be called once for each parameter.