I a number of objects that I would like to display within a property grid as they are selected by the user. I am aware that property descriptions can be set within each objects class, however I require that the descriptions differ between different instances of the same object.
Is there a way I can set a description for the entire object at run time that displays regardless of what property is selected within the property grid?
For example, if I had the following class
public class Person
{
public String Name { get; set; }
public String Age { get; set; }
public Person(String n, int a)
{
this.Name = n;
this.age = a;
}
public Person()
{
}
}
and I created a Person object in the following manner
Person Frank = new Person(Frank, 22);
and displayed that object in a property grid like so
propertyGrid1.SelectedObject = Frank;
I would like the ability to provide a description for the entire object rather than the name and age attributes of the Person class. And, because I want the description to pertain to the Frank object in particular, I would like to be able to set this description not only based on what type of object is selected, but the particular instance of that object. Is this possible?
The PropertyGrid only shows descriptions for the properties, not the object. That said, you could implement ICustomTypeDescriptor on your object and override the GetProperties methods. There you could inject a custom DescriptionAttribute.
A longer tutorial on this interface can be found here and here.
CodeNaked as the right answer. It makes sense for a PropertyGrid to only display a description for the property that is currently selected, not for the whole instance. What would be the benefit? If you really need to display a message based on the targetted instance, why not create a label on top or bottom of the grid? Its content could be based on a custom attribute of yours or on your own DescriptionProvider...
Related
I have a ListBox, and it's items consist of custom class objects (can be any class).
Then I set the DisplayMemberPath so the ListBox shows the right property of that custom class fine.
Now I need to enumerate the Items list of ListBox, and get the DisplayMember value of each item in the list, without knowing the type of the class in the list. Is there any way to get this DisplayMember value without Reflection?
In WPF, you don't need to implement an interface, or a base class for a container control to read the value of a property. In an ideal world, it would make sense to declare a base class or interface and have all of your custom classes extend, or implement these, but the benefit of that is really to keep your data type safe.
For example, in WPF, this is perfectly legal and will work just the same:
public class RadioButtonData
{
public string Label { get; set; }
public bool IsSelected { get; set; }
}
public class CustomData
{
public string Label { get; set; }
public string Value { get; set; }
}
...
private ObservableCollection<object> objects = new ObservableCollection<object>();
public ObservableCollection<object> Objects
{
get { return objects; }
set { objects = value; NotifyPropertyChanged("Objects"); }
}
...
Objects.Add(new RadioButtonData() { Label = "Some Value" });
Objects.Add(new CustomData() { Label = "Another Value" });
...
<ListBox ItemsSource="{Binding Objects}" DisplayMemberPath="Label" />
So as long as your various classes have the same name of property, then they will all be displayed in the same way, like above. They don't even have to be of the same type... just as long as the name matches that used in the ListBox.DisplayMemberPath property.
UPDATE >>>
Ah sorry, I misunderstood your question. In the case that you want to access these property values in code, then you have four basic options:
Define an Interface with a particular property and make your custom classes implement it.
Declare a base class with a particular property and make your custom classes extend it.
Create a (potentially long) section of if else statements that checks the type of each object and then accesses the relevant property.
Use reflection.
In my personal opinion, I would recommend options 1 or 2 first, then 4 and lastly 3. I'm really not sure what you have against reflection, but it's really not that bad, or slow... I'd certainly prefer to use it rather than having an else if statement for every possible type used.
Very basic question here, look at my property Order in my customer class. Wondering what is the formal name of a property type like this is (yes, this could also be a list).
public class Customer
{
public int ID { get; set; }
public string Name { get; set; }
public Order Orders { get; set; } // what am i called?
}
public class Order
{
public int ID { get; set; }
public string SomeProperty { get; set; }
}
Its the same thing. Its called a "Property". There is no different name for it. Consider your SomeProperty which is of type string. string is also a class and SomeProperty is its object. Same convention with your class would follow as well.
From C# Language Specification.
1.6.7.2 Properties
A property is declared like a field, except that the declaration ends
with a get accessor and/or a set accessor written between the
delimiters { and } instead of ending in a semicolon.
So the term "property" in C# is associated with the accessors (get/set)
from ECMA-334 8.7.4:
A property is a member that provides access to a characteristic of an object or a class.
It doesn't matter what type the property accesses. The property itself is just to provide access to it.
So, bottom line, a property is a property no matter what type it accesses.
It's just a property - there's not a formal name for it.
The concept itself is called Composition. Basically, you want to be able to use a Customer object to get information about an Order, but you don't want the logic that gets that information to live in Customer. So, you have a member who is an Order and Order encapsulates the Order behavior.
You could say that a Customer is composed of Order along with other values.
Have a link: http://www.javaworld.com/jw-11-1998/jw-11-techniques.html
Not that you asked this, but you probably will want an actual collection of Orders. You could start with
public List<Order> Orders;
It's still a property. It just gets/sets an object, which is an instance of a class.
I have a custom control with a public collection marked as DesignerSerializationVisibility.Content.
When I add items to the collection using the designer, it adds them to the designer file and assigns all desired values but it gives each element of the collection a generic name, such as MyClass1, MyClass2, etc. I want the "Name" property of each item to become the code name of the item so that I can then access the item by its name in code.
This is the functionality of how a ContextMenuStrip and ToolStrip works. In those cases, the Name property shows up as (Name) in the property grid.
Is there an attribute or something I can use to gain this functionality? Or do I have to write a whole custom designer dialog? If so, what's an example of the simplest way I could go about achieving this?
You can try inheriting from Component to get that feature.
In this example, I created a class called PanelItem, which will be the class used in my collection by my own Panel class. I added DesignTimeVisible(false) so that it doesn't populate the component tray in the designer.
Also, I added a Name property that is hidden from the designer but can be used in code. It seemed to work in my tests:
[DesignTimeVisible(false)]
public class PanelItem : Component {
[DefaultValue(typeof(string), "")]
public string PanelText { get; set; }
private string name = string.Empty;
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
public string Name {
get {
if (base.Site != null) {
name = base.Site.Name;
}
return name;
}
set {
name = value;
}
}
}
Then my custom panel control:
public class MyPanel : Panel {
private List<PanelItem> panelItems = new List<PanelItem>();
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public List<PanelItem> PanelItems {
get { return panelItems; }
}
}
Resulted in:
I believe your custom control itself is going to require a DesignerSerializer, and that merely decorating the collection with the the DesignerSerializationVisibility.Content will not be sufficient.
I used ILSpy to check: ToolStrip has its DesignerSerializer set to an internal ToolStripCodeDomSerializer, which I think is responsible for generating all the code properties involved.
I think implementing this will be a bit of specialized work. Here's the MSDN article to get you started: http://msdn.microsoft.com/en-us/library/ms171834.aspx. You're looking for an implementation of the CodeDomSerializer, I believe: http://msdn.microsoft.com/en-us/library/system.componentmodel.design.serialization.codedomserializer.aspx.
I want to display multiple instances of one class in my PropertyGrid. The class looks like this:
public class Parameter
{
[Description("the name")]
public string Name { get; set; }
[Description("the value"), ReadOnly(true)]
public string Value { get; set; }
[Description("the description")]
public string Description { get; set; }
}
I have many instances of that class in a TreeView. When I select one of them in my TreeView, the properties show up in the PropertyGrid as expected. So far so good, but I want to customise this behaviour in the following way:
For each single instance I want to be able to prevent the user from modifying a specific property. By setting ReadOnly(true) within my class (as you can see in the example above), all Value properties will be disabled on a class-level.
After some research I found the following solution which gives me the opportunity to enable/disable a specific property at runtime:
PropertyDescriptor descriptor = TypeDescriptor.GetProperties(this)["Value"];
ReadOnlyAttribute attr =
(ReadOnlyAttribute)descriptor.Attributes[typeof(ReadOnlyAttribute)];
FieldInfo isReadOnly = attr.GetType().GetField(
"isReadOnly", BindingFlags.NonPublic | BindingFlags.Instance);
isReadOnly.SetValue(attr, false);
This approach works just fine but unfortunately also on class-level only. This means if I set the Value's isReadOnly to false, all of my Parameter-objects have the Value property writeable. But I want this ONLY on that one particular object (thus object-level). I really don't want to create separate classes for read/write and readonly properties.
As I am running out of ideas, your help is much appreciated :)
Thanks in advance!
EDIT: I need the readonly properties to be grayed-out, so the user can see that it's not allowed or possible to edit them.
EDIT: Linked article has been removed (I hope just temporary). You can fine a viable alternative in answers to How to add property-level Attribute to the TypeDescriptor at runtime?. Basically you have to add (at run-time) ReadOnlyAttribute through a TypeDescriptor for that property.
Take a look at this old but nice article on CodeProject, it contains a lot of useful tools for the PropertyGrid.
Basically you provide a class or a delegate that will be used to get the attributes of your properties. Because it will be invoked passing the instance of the object you want to get attributes for then you'll be able to return (or not) the ReadOnlyAttribute with a per object basis. Shortly: apply a PropertyAttributesProviderAttribute to your property, write your own provider and replace attributes from the PropertyAttributes collection based on the object itself (and not on the class)
You can wrap the object with a custom type descriptor, but I think that would be overkill, because you have to create a new typedescriptor-derived class.
So, a simplest solution would be to have a flag, something like:
public class Parameter
{
private string thevalue;
[Browsable(false)]
public bool CanEditValue { get; set; }
[Description("the name")]
public string Name { get; set; }
[Description("the description")]
public string Description { get; set; }
[Description("the value"), ReadOnly(true)]
public string Value {
get { return this.thevalue; }
set { if (this.CanEditValue) this.thevalue = value; }
}
}
I have a problem that is difficult to explain. Essentially I have a list of a certain class we can call MyObj. One of the properties of this object is a custom list itself. I would like to bind this List to a dataGridView and have this particular property that is also a list show up. Any ideas? Am I being clear enough? :-P..
Here is the idea. I have my own custom list object overriding the ToString() method:
public class CategoriesList : List<Category>
{
public override string ToString()
{...}
}
This is used as a property in an object such as:
public MyObj
{
public string Property1 {get; set; }
public string Property2 {get; set; }
public CategoriesList Categories {get; set; }
}
In turn, I have a list of these objects such as:
List<MyObj> myDataSouce = SomeRepository.GetMyObjList();
Where I bind this to a datagrid view:
MyDataGridView.DataSource = myDataSource;
Property1 and Property2 are automatically generated. Is there any way to have the CategoriesList property be added as well? I previously thought Overriding the ToString() method on a class would be enough..
I am really lost on this one as I have no idea how to even google for it :-P
Assuming that you'd like to display a specific value in place of the list in the datagridview, you'll want to use a custom TypeConverter. Otherwise you'll need to place a control in the datagridview column that supports lists, like a drop down list and bind to that.
For the former:
Basically decorate your categories property with a custom typeconverter:
[TypeConverter(typeof(MyConverter))]
public CategoriesList Categories { get; set; }
Then use a custom type converter that basically tells the datagrid that when it encounters the categories property what do display:
public class MyConverter : TypeConverter
{
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
if (value is CategoriesList) {
return value.ToString();
}
return base.ConvertFrom(context, culture, value);
}
}
You'll need to add your column to be databound manually by adding an unbound column and specify the DataPropertyName for the property to be mapped to that column, in this case "Categories"
If you're looking to display second level properties as well then this may help:
http://blogs.msdn.com/b/msdnts/archive/2007/01/19/how-to-bind-a-datagridview-column-to-a-second-level-property-of-a-data-source.aspx
This might help... look at my answer there, I haven't tried it with a property that is also a type of list but I think the idea is the same.
Or this one as well, I also have an answer there with a sample code too...