1.2. Connecting Data

There are two ways how you can pass data to a chart: through the DataProvider interface or using the datasource mechanism.

  • The DataProvider interface has a standard implementation: ListDataProvider class. It contains a list of DataItem instances, each one containing a set of key-value pairs. An instance of DataProvider is passed to the setDataProvider() method of chart configuration. This approach to providing chart data is the most universal, but it requires you to create instances of DataProvider and DataItem in a screen controller.

  • A CollectionDatasource type datasource can be assigned to a Chart component by invoking the setDatasource() method. This approach requires an entity that will represent chart data. It may be convenient when such entity already exists in the application data model and also when chart data should be displayed as a table.

Section 1.4, “Example of Working with Charts” illustrates both approaches to providing chart data.

Entity properties or the values contained in an instance of DataProvider which are used for display purposes are defined in the chart attributes. The set of chart attributes may differ for different chart types. For example, for the chart:pieChart component, you should define the valueField and titleField attributes. The following types are allowed for attribute values: Integer, Long, Double, String, Boolean, Date.

Dynamic addition of data to an existing chart is not supported; you should redraw the entire chart to display new data. This can be done using the repaint() method.

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