xpo-devexpress-dot-xpo-dot-metadata-dot-valueconverter-dot-convertfromstoragetype-x28-system-dot-object-x29.md
When overridden in a derived class, converts the value which is stored in a data store to the persistent property’s value.
Namespace : DevExpress.Xpo.Metadata
Assembly : DevExpress.Xpo.v25.2.dll
NuGet Package : DevExpress.Xpo
public abstract object ConvertFromStorageType(
object value
)
Public MustOverride Function ConvertFromStorageType(
value As Object
) As Object
| Name | Type | Description |
|---|---|---|
| value | Object |
An object which represents the value to convert.
|
| Type | Description |
|---|---|
| Object |
An object which represents the converted value.
|
The following code example demonstrates how to store your boolean data in the database using the “T” string for true and “F” for false by defining a new ValueConverter descendant. You may need this converter when using an existing database in which boolean properties are stored such form.
//...
[Size(1), ValueConverter(typeof(BooleanToStringValueConverter))]
public bool Answer {
get { return GetPropertyValue<bool>(nameof(Answer)); }
set { SetPropertyValue<bool>(nameof(Answer), value); }
}
//...
public class BooleanToStringValueConverter : ValueConverter {
public override object ConvertFromStorageType(object value) {
return Convert.ToString(value) == "T";
}
public override object ConvertToStorageType(object value) {
return Convert.ToBoolean(value) ? "T" : "F";
}
public override System.Type StorageType {
get { return typeof(string); }
}
}
'...
<Size(1), ValueConverter(GetType(BooleanToStringValueConverter))> _
Public Property Answer() As Boolean
Get
Return GetPropertyValue(Of Boolean)(NameOf(Answer))
End Get
Set(ByVal value As Boolean)
SetPropertyValue(Of Boolean)(NameOf(Answer), value)
End Set
End Property
'...
Public Class BooleanToStringValueConverter
Inherits ValueConverter
Public Overrides Function ConvertFromStorageType(ByVal value As Object) As Object
Return Convert.ToString(value) = "T"
End Function
Public Overrides Function ConvertToStorageType(ByVal value As Object) As Object
Return If(Convert.ToBoolean(value), "T", "F")
End Function
Public Overrides ReadOnly Property StorageType() As System.Type
Get
Return GetType(String)
End Get
End Property
End Class
See Also