Re: capture Data Modified from database real time? - C# Discussion Boards

Re: How can I implement a Brush property for a control?

27-Dec-07 5:09

If you use Reflector, you can see that the Image class declares that ImageConverter should be used as it's TypeConverter. As shown here:

[Serializable,
...,
TypeConverter(typeof(ImageConverter))]
public abstract class Image : MarshalByRefObject,
ISerializable, ICloneable, IDisposable
{
//....
}

ImageConverter is what is used by Visual Studio to "serialize" the Image for use by InitializeComponent. There is no TypeConverter defined for the Brush class (nor SolidBrush, TextureBrush, etc). So these types cannot be serialized as you want.

Typically, controls would expose other properties and build the Brush when needed. So you could define a Color property, then build a SolidBrush when you are performing your drawing. Or if you want a TextureBrush, you would have a Image property.

Take care,
Tom

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ctoma200528-Dec-07 2:31

ctoma2005

28-Dec-07 2:31

Hmm,thanks for the answer,it makes sense. But..I can't figure out why visual studio doesn't use my custom type converter for that property. I use it like this:

<br />
 [TypeConverter(typeof(BrushConverter))]<br />
        public Brush Brush<br />
        {<br />
            get<br />
            {<br />
                ...<br />

I mean..it uses the BrushConverter to convert from Brush to string and back..but it doesn't use it to convert from Brush to InstanceDescriptor(i.e the class that tells it how to serialize the code).

I want the developers to choose the type of brush they want to use. What if I make the property if type string..and parse the string in the OnPaint() ? That is kind of weird..but it might work.

Any ideea why can't I use a custom converter for the property?

Re: How can I implement a Brush property for a control?

TJoe28-Dec-07 3:41

capture Data Modified from database real time?

28-Dec-07 3:41

If you can email over the code to BrushConverter, then I can take a look.

Your last question brought up another option, which is to provide two properties (e.g. Brush and BrushString). The Brush property would not be serialized (e.g. there should be a ShouldSerializeBrush() method that always returns false). The BrushString property would be serialized, but would not be browsable. This way it will save the "string" (or byte[]) which would hold the serialized version of the Brush in the designer code.

In the "get" for BrushString, you would serialize the Brush into a string and return that. In the "set" for BrushString, you would deserialize the Brush and save it. The Brush property would work normally.

Take care,
Tom

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jason_mf27-Dec-07 2:25

jason_mf

27-Dec-07 2:25

I have a program.
it need to process a little of data when data modifed in database(update or insert new or delete).How to get this data real time?

Or how program get the data from database's trigger?

Re: capture Data Modified from database real time?

Giorgi Dalakishvili27-Dec-07 2:42

Re: capture Data Modified from database real time?

27-Dec-07 2:42

You can use SqlDependency Class[^] to get notified about changes in database data.

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jason_mf27-Dec-07 3:02

jason_mf

27-Dec-07 3:02

MSDN:"SqlDependency was designed to be used in ASP.NET or middle-tier services where there is a relatively small number of servers having dependencies active against the database."

Mine is WinForm program, can use it too?

Re: capture Data Modified from database real time?

Giorgi Dalakishvili27-Dec-07 3:10

27-Dec-07 3:10

Yes, you can. Here is an example:
SqlDependency in a Windows Application[^]

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linq update problem

brain2cpu27-Dec-07 2:20

brain2cpu

27-Dec-07 2:20

It works:
var names = from n in db.Contacts
where n.Name.Contains("aaa")
select n;
foreach(var t in names)
{
t.Name = "xxx";
}
db.SubmitChanges();

Not works (no errors but the Name field does not change)
public class tmp
{
public string Name {get; set;}
public int ID { get; set; }
public string Group { get; set; }
}
var names = from n in db.Contacts
where n.Name.Contains("aaa")
select new tmp { Name = n.Name, ID = n.Id, Group = n.Group.Name };
foreach(var t in names)
{
t.Name = "xxx";
}
db.SubmitChanges();

how can I do this without fetching all database columns?

Thanks

TJoe27-Dec-07 5:17

27-Dec-07 5:17

Sorry, if you are trying to update the Name on the contact object, then you will need to select the contact object (as you do with the first code example).

In the second example you are creating a new object (with the same Name, Id and Group), and updating it's name. You are not updating the original contact object.

Take care,
Tom

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brain2cpu27-Dec-07 20:37

brain2cpu

27-Dec-07 20:37

I thought about this, but I did hope it's my mistake. So, there is no way to have an "updateable select" using just a few of table columns? The original goal was something like:
dataViewGrid.DataSource = from .....
and permit updates, ... in grid having just 3-4 columns (not all 15).

TJoe28-Dec-07 3:47

28-Dec-07 3:47

Yes it should be possible to only retrieve 3-4 columns from a DB table and still allow those columns to be updated. This is assuming ofcourse that one of those columns is a unique identifier for the associated row (e.g. the Primary Key).

For your code, it really depends on what db.Contacts returns. Since I can't see that code, I'm assuming that it returns a list of Contact objects that have all 15 columns. In order to only return 3-4 columns, then the Contact object would need to only have the 3-4 columns.

If you can provide some more of the code that would help (either through email or here). Let me know if this doesn't make sense also. But basically, the "object" that holds the data for a single row in your table is what must be updated. Therefore, you would need to change how many columns the "object" has before the code you posted earlier.

Take care,
Tom

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brain2cpu30-Dec-07 23:42

brain2cpu

30-Dec-07 23:42

db.Contacts and 3 more classes are generated by sqlmetal, the solution would be to modify this classes to have properties just for database columns I need? (the primary key is in my "column-wish-list"). This probably would work but it seems to me way to complicated and across the program there are about 5 column combinations.
Thanks

File Dialoge

sudany_zool27-Dec-07 1:25

sudany_zool

27-Dec-07 1:25

I want to set the file of types in Open File Dialoge to a specific type such as ".bmp"

Giorgi Dalakishvili27-Dec-07 1:33

27-Dec-07 1:33

Why don't you read the documentation? OpenFileDialog has a property called filter which allows you to set file type.

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sudany_zool27-Dec-07 1:49

sudany_zool

27-Dec-07 1:49

could u please give me an example on how to use it !

Giorgi Dalakishvili27-Dec-07 2:02

27-Dec-07 2:02

As I already said in my first reply, why don't you read docs? Or google? Or search here, on codeproject? No one is going to do it instead of you. Learn googling.

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sudany_zool27-Dec-07 2:10

sudany_zool

27-Dec-07 2:10

i didnt say that i wanna some one to do it for , all i wanna is some help and thankx anyway for the adive.

Giorgi Dalakishvili27-Dec-07 2:43

27-Dec-07 2:43

If you read documentation, you will find everything you need.

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