expressappframework-113285-ui-construction-views-layout-list-view-column-generation.md
XAF automatically generates all List Views according to the Application Model‘s information. This topic describes the specific rules used to generate a default set of List View columns.
Note
The column generation logic is declared in the ModelListViewColumnsNodesGenerator class, which is the Node Generator (see Extend and Customize the Application Model in Code).
In this section, simple property columns are generated for the following persistent class:
public class ObjectA : BaseObject {
public virtual string PropertyA1 { get; set; }
public virtual string PropertyA2 { get; set; }
}
// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.
public class ObjectA : BaseObject {
public ObjectA(Session session) : base(session) { }
private string propertyA1;
private string propertyA2;
public string PropertyA1 {
get { return propertyA1; }
set { SetPropertyValue(nameof(PropertyA1), ref propertyA1, value); }
}
public string PropertyA2 {
get { return propertyA2; }
set { SetPropertyValue(nameof(PropertyA2), ref propertyA2, value); }
}
}
The ListView ‘s and LookupListView ‘s Columns node contains child nodes generated for this class. The following image illustrates this node in the Model Editor:
The column order specified using the IModelNode.Index properties corresponds to their declaration order. These columns are visible when their Index values are positive or zero.
The following attributes, applied in code, affect column visibility:
If the class has a default or friendly key property (see XafDefaultPropertyAttribute, DefaultPropertyAttribute, and FriendlyKeyPropertyAttribute), its Lookup List View contains a single column corresponding to this property. In the general List View, the default property column has an index of zero and is displayed first. The code below demonstrates the DefaultProperty attribute in use, and the image illustrates the result.
[DefaultProperty(nameof(PropertyA2))]
public class ObjectA : BaseObject {
// ...
The FriendlyKeyProperty attribute has the same effect.
If the business class property name matches or contains one of the DevExpress.ExpressApp.DC.TypeInfo.DefaultPropertyNames values (excluding inherited properties), then it is considered as the default property. The DefaultPropertyNames values: Name, Title, Subject, Caption, Description, Benennung, Nombre, Nome. If you want to modify the DefaultPropertyNames collection, refer to the following help topic: Declare a Property with a Specific Name.
public class ObjectA : BaseObject {
// ...
public string ObjectName {
// ...
The DefaultProperty attribute overrides this behavior.
The corresponding column is not generated if the property is decorated with HideInUI.All, HideInUI.ListView or HideInUI.ListViewColumn. If it is decorated specifically with HideInUI.ListViewColumn, you can then use the Object Model dialog to generate the column back (see List View Columns Customization) (available only in Win and Blazor).
The corresponding column is not generated if the property is decorated with the Browsable attribute and false is passed as the parameter (see BrowsableAttribute).
The corresponding column is generated but remains invisible if the property is decorated with the VisibleInListViewAttribute attribute and false is passed as the parameter. The Columns node’s IModelNode.Index property is set to -1. You can use the Column Chooser or Model Editor to unhide such a column (see List View Columns Customization).
When a class has a default property, XAF generates one column for this property in the Lookup List View. To add a column in code, decorate the required property with the VisibleInLookupListViewAttribute and pass true as the attribute parameter. When the class has no default property, all property columns are generated in the Lookup List View. To hide a column corresponding to a certain property, decorate the property with the VisibleInLookupListViewAttribute, and pass false as the attribute parameter.
To demonstrate how the reference property columns are generated, the persistent class demonstrated in the previous section, will be extended with the PropertyA3 reference property of the ObjectB type
public class ObjectA : BaseObject {
public virtual ObjectB PropertyA3 { get; set; }
}
[DefaultProperty(nameof(PropertyB2))]
public class ObjectB : BaseObject {
public virtual string PropertyB1 { get; set; }
public virtual string PropertyB2 { get; set; }
}
// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.
public class ObjectA : BaseObject {
// ...
private ObjectB propertyA3;
public ObjectB PropertyA3 {
get { return propertyA3; }
set { SetPropertyValue(nameof(propertyA3), ref propertyA3, value); }
}
}
[DefaultProperty(nameof(PropertyB2))]
public class ObjectB : BaseObject {
public ObjectB(Session session) : base(session) { }
private string propertyB1;
public string PropertyB1 {
get { return propertyB1; }
set { SetPropertyValue(nameof(propertyB1), ref propertyB1, value); }
}
private string propertyB2;
public string PropertyB2 {
get { return propertyB2; }
set { SetPropertyValue(nameof(propertyB2), ref propertyB2, value); }
}
}
A column is generated to display the PropertyA3 property.
In the UI, the PropertyA3 displays the PropertyB2‘s value, because the PropertyB2 is the ObjectB class’ default property.
If the PropertyA3 property is decorated by the ExpandObjectMembersAttribute with the ExpandObjectMembers.InListView parameter, then the columns for all ObjectB class’ properties are generated in the ObjectA List View.
public class ObjectA : BaseObject {
// ...
[ExpandObjectMembers(ExpandObjectMembers.InListView)]
public ObjectB PropertyA3 {
// ...
Consider the following ObjectC class, derived from the ObjectA class:
public class ObjectC : ObjectA {
public virtual string PropertyC1 { get; set; }
public virtual string PropertyC2 { get; set; }
}
// Make sure that you use options.UseChangeTrackingProxies() in your DbContext settings.
public class ObjectC : ObjectA {
public ObjectC(Session session) : base(session) { }
private string propertyC1;
public string PropertyC1 {
get { return propertyC1; }
set { SetPropertyValue(nameof(propertyC1), ref propertyC1, value); }
}
private string propertyC2;
public string PropertyC2 {
get { return propertyC2; }
set { SetPropertyValue(nameof(propertyC2), ref propertyC2, value); }
}
}
Typically, the columns for this class properties are generated as usual (see the description of ObjectA List Views column generation above). The columns for derived properties are generated as hidden (with -1 indexes). Note the following specifics:
The intended behavior when the derived class has no default property, and its ancestor has a default property
The intended behavior, when the derived class has no public fields and properties
Each column has an IModelColumn.Width property that specifies its width in ASP.NET Core Blazor and Windows Forms application. The following table shows the default width values:
| Type of Property | Default Width | Default Width in Lookups |
|---|---|---|
| The property is the class’ default or friendly key property (see DefaultPropertyAttribute, FriendlyKeyPropertyAttribute). If a property contains “Name” in its name (excluding inherited properties), this property is also considered default. | 400 | 340 |
A short value type property - int, float, double, decimal, char or bool. | 50 | 50 |
Other properties (string and so on) | 70 | 50 |
Note
In ASP.NET Core Blazor applications, the default column width is ignored.
Usually the default property contains the most details in the class, so a wide column is automatically generated for it. Short type values do not take much screen space, and their default columns are narrow.
List Views are sorted by the default property values in ascending order (if the default property type is System.IComparable). The default column’s IModelColumn.SortIndex is set to 0, and IModelColumn.SortOrder is set to ColumnSortOrder.Ascending. Other columns have the default SortIndex and SortOrder (-1 and ColumnSortOrder.None, respectively) values.
See Also