Saving and Loading

Updated on Oct 1, 2026

The RadFilter server-side API offers two methods for saving and loading RadFilter expressions by user:

• SaveSettings - serializes the control expressions to Base64 encoded string;

• LoadSettings - Loads the provided state in the control. The parameter for this method must be * Base64 encoded * string representing saved control expressions.

You see how they work in the Save/Load RadFilter expressions live demo.

All versions of RadFilter prior to Q3 2010 use the ObjectStateFormatter by default. Due to the nature of this formatter, it is not possible to deserialize settings, saved with different version of the assembly. From Q3 2010 on, the BinaryFormatter is set as default.

You could get or change the default formatter using the SettingsFormatter property (introduced in Q3 2010).

• RadFilter.SettingsFormatter.BinaryFormatter - this is the default formatter for UI versions Q3 2010 and later. The advantage of this formatter is that it will work even if you save the state with one version of the assembly and then restore it with another. The drawback is that the BinaryFormatter does not work in medium trust.

• RadFilter.SettingsFormatter.ObjectStateFormatter- the default formatter in UI versions prior to Q3 2010. This formatter works flawlessly in medium trust but it won't deserialize settings, saved with another version of the assembly.

It is possible to use your own formatter by overriding the GetSettingsFormatter method. For more information about the formatters, please visit the following link: IFormatter Interface (MSDN)

Troubleshooting Saved State

When a saved state does not appear to load, first identify which persistence API created the state. SaveSettings and LoadSettings save and restore RadFilter expressions as a Base64-encoded string. The Persistence Framework uses SaveState and LoadState instead, and exposes the RadFilter FilterExpression as a persisted property. Do not use the troubleshooting steps for one persistence API with state produced by the other.

Check the following conditions:

• If you create field editors programmatically, recreate them on every request in Page_Init before loading the saved settings. The field names and data types must be available when RadFilter restores the expressions.

• Treat FieldName as the stable identifier used to match an expression to an editor. Recreate the editor with the same FieldName and DataType before calling LoadSettings. Spaces in FieldName are not defined as an error or as a supported special case in this article; if a state fails with a null field-name lookup, compare the saved field names with the recreated editors and test a stable identifier without spaces. Use DisplayName for the human-readable label.

• If RadFilter filters a RadGrid, verify that the FilterContainerID points to the grid and that the grid is configured for filtering. See RadGrid Filtering with RadFilter for the required integration settings.

• If you restore the state through the Persistence Framework, call the grid's Rebind() method after LoadState() so the restored settings take effect. This step applies to the Persistence Framework workflow; it is not a replacement for LoadSettings when the state was saved directly by RadFilter.

• If the state was created after an upgrade, do not assume that a legacy-state conversion is required. Confirm whether the application uses LoadSettings/SaveSettings or LoadState/SaveState, and verify that the saved string is loaded after the RadFilter configuration and any dynamic field editors have been recreated.