The DataColumn property caption is of no use

  • Thread starter Thread starter Tony
  • Start date Start date
T

Tony

Hello!

I can't see any use of the property Caption in the DataColumn class because
you can't change the column title by using that property.
Here I have a short code snippet where I change the Caption on the third
added column to Limit but if I look at the
DataTable its still show the column title as CreditLimit so setting the
Caption has no effect.

I hope someone can correct me if I'm wrong about this caption property on
the DataColum class.

private void CreateDataTable()
{
DataTable table;
DataColumn column;

table = new DataTable("Customers");

//CustomerID column
column = table.Columns.Add("CustomerID",
System.Type.GetType("System.Int32"));
column.Unique = true;

//CustomerName column
column = table.Columns.Add("CustomerName",
System.Type.GetType("System.String"));
column.Caption = "Name";

//CreditLimit
column = table.Columns.Add("CreditLimit",
System.Type.GetType("System.Double"));
column.DefaultValue = 0;
column.Caption = "Limit";

table.Rows.Add(new object[] { 1, "Jonathan", 23.44 });
table.Rows.Add(new object[] { 2, "Bill", 56.87 });
}

//Tony
 
I can't see any use of the property Caption in the DataColumn class
because you can't change the column title by using that property.
Here I have a short code snippet where I change the Caption on the third
added column to Limit but if I look at the
DataTable its still show the column title as CreditLimit so setting the
Caption has no effect.

I hope someone can correct me if I'm wrong about this caption property on
the DataColum class.
Click to expand...

Just a guess, but this property is probably used by other code to set a
caption when autogenerating a form or report based on the DataTable,
assuming you want to use something other than the underlying column's name.
MS Access has had this capability for years. It's PURELY for display. MSDN
says this:

You can use the Caption property to display a descriptive or friendly name
for a DataColumn.
 
Jeff Johnson said:
Just a guess, but this property is probably used by other code to set a
caption when autogenerating a form or report based on the DataTable,
assuming you want to use something other than the underlying column's
name. MS Access has had this capability for years. It's PURELY for
display. MSDN says this:

You can use the Caption property to display a descriptive or friendly name
for a DataColumn.
Click to expand...

It has no affect if you use it as the MSDN says like
You can use the Caption property to display a descriptive or friendly name
for a DataColumn.
If will has no effect ?
So this caption is of no use.

//Tony

//Tony
 
Tony said:
It has no affect if you use it as the MSDN says like
You can use the Caption property to display a descriptive or friendly name
for a DataColumn.
If will has no effect ?
So this caption is of no use.
Click to expand...

How can I say it clearer? It is of use to OTHER things. If you don't use
those other things then it's meaningless FOR YOU, but not necessarily for
other people.
 
Jeff Johnson said:
How can I say it clearer? It is of use to OTHER things. If you don't use
those other things then it's meaningless FOR YOU, but not necessarily for
other people.
Click to expand...

What I want to say is that the manual say the following
"You can use the Caption property to display a descriptive or friendly name
for a DataColumn"
So this would mean that the header for the column in a DataGridView or
DataGrid would have the name from the Caption but that is not what would
happen."

So the manual about this Caption property is completely wrong no matter what
you say.

//Tony
 
What I want to say is that the manual say the following
"You can use the Caption property to display a descriptive or friendly
name for a DataColumn"
So this would mean that the header for the column in a DataGridView or
DataGrid would have the name from the Caption but that is not what would
happen."

So the manual about this Caption property is completely wrong no matter
what you say.
Click to expand...

Okay, a quick Web search seems to indicate that this property is not used by
any built-in Microsoft controls. However, its purpose remains the same: it's
there for you to STORE a string to be used in place of the column name.
However, it seems like it's UP TO YOU to actually use this name.

I guess it's like the Tag property. Will you suggest the Tag property is
useless simply because nothing built-in to the Framework automatically uses
it?

Also, I argue that MSDN is RIGHT, but not CLEAR. (Reminds me of the old joke
about the guy in the balloon....) I says "YOU can use the Caption
property..." and it really means it: it's there for YOU, and only you,
apparently.
 
What I want to say is that the manual say the following
"You can use the Caption property to display a descriptive or friendly
name for a DataColumn"
So this would mean that the header for the column in a DataGridView or
DataGrid would have the name from the Caption but that is not what would
happen."

So the manual about this Caption property is completely wrong no matter
what you say.
Click to expand...

Nothing prevents you from writing the TonyGrid class that
does display that property.

Maybe there is a JeffGrid that does that.

The fact that DataGridView and DataGrid does not use it is not the
same that nothing will ever use it.

Arne
 
Maybe there is a JeffGrid that does that.
Click to expand...

I've never even considered writing a grid. Lots o' work! However, I did
write a "canvas" control once. It was basically a stripped-down version of
the Windows Workflow designer. Quite a bit of work went into displaying the
boxes that could be placed on the canvas, I can tell you! And the piece I
was most proud of was the "thumbnail navigator," which you use to quickly
move to parts of the canvas that aren't visible.

Writing controls is kind of cool, if you're willing to put in the time. I
applaud those who do.
 
The fact that DataGridView and DataGrid does not use it is not the
same that nothing will ever use it.

Arne
Click to expand...

I am no expert with the grid. But if the DataGrid itself does not use it,
how can it make claim that the field will be used to display as alternate.
It is just a all-purpose property like a Tag. No ?
 
I am no expert with the grid. But if the DataGrid itself does not use it,
how can it make claim that the field will be used to display as alternate.
It is just a all-purpose property like a Tag. No ?
Click to expand...

The trick is in the wording. The MSDN description never says that anything
WILL use this property, just that it CAN be used for such a purpose. I agree
that it SUGGESTS that something will use it, and since Microsoft shouldn't
be making claims about other people's software, that also SUGGESTS that
something Microsoft wrote will be the consumer, but that isn't the case.

My guess: they intended to use it and then scrapped the idea.
 
Peter Duniho said:
[...]
I am no expert with the grid. But if the DataGrid itself does not use
it,
how can it make claim that the field will be used to display as
alternate.
It is just a all-purpose property like a Tag. No ?
Click to expand...

The trick is in the wording. The MSDN description never says that
anything
WILL use this property, just that it CAN be used for such a purpose.
[...]
Click to expand...

More to the point of Phil's question: when he writes "if the DataGrid
itself does not use it, how can it make claim.", he's falling into the
trap of making a bogus assumption about what's claiming what.

"It" (which in that statement must be the DataGrid type) does _not_ make
any such claim. The documentation describing the Caption property isn't
part of DataGrid at all. It's part of the DataColumn type.
Click to expand...

Actually, I think he was being fast and loose with his pronouns. My take:

"But if the DataGrid itself does not use it [the Caption property of the
DataColumn], how can it [the DataColumn] make claim that the field [the
Caption property (not "field")] will be used to display as alternate."

Isn't English fun?
 
Actually, I think he was being fast and loose with his pronouns. My take:
"But if the DataGrid itself does not use it [the Caption property of the
DataColumn], how can it [the DataColumn] make claim that the field [the
Caption property (not "field")] will be used to display as alternate."

Isn't English fun?
Click to expand...

I never read the documentation. But can someone show me a place in the
framework that uses the property to display the so called 'caption' ? Sure
you or I can use it to display, I can also use it for something else too.
 
Actually, I think he was being fast and loose with his pronouns. My take:

"But if the DataGrid itself does not use it [the Caption property of the
DataColumn], how can it [the DataColumn] make claim that the field [the
Caption property (not "field")] will be used to display as alternate."

Isn't English fun?
Click to expand...

I never read the documentation. But can someone show me a place in the
framework that uses the property to display the so called 'caption' ? Sure
you or I can use it to display, I can also use it for something else too.
Click to expand...

That's what we're saying: there doesn't seem to be any place that the
framework uses it. But we're also saying that the documentation doesn't
ACTUALLY SAY that some other part of the framework WILL use this property;
most people simply INFER that. (I certainly did, but that was mainly due to
my experience with Access. A more thorough search revealed that this
property is just...there.)
 
Hello!

I can't see any use of the property Caption in the DataColumn class because
you can't change the column title by using that property.
Here I have a short code snippet where I change the Caption on the third
added column to Limit but if I look at the
DataTable its still show the column title as CreditLimit so setting the
Caption has no effect.

I hope someone can correct me if I'm wrong about this caption property on
the DataColum class.
OK you're wrong ;)
private void CreateDataTable()
{
DataTable table;
DataColumn column;

table = new DataTable("Customers");

//CustomerID column
column = table.Columns.Add("CustomerID",
System.Type.GetType("System.Int32"));
column.Unique = true;

//CustomerName column
column = table.Columns.Add("CustomerName",
System.Type.GetType("System.String"));
column.Caption = "Name";

//CreditLimit
column = table.Columns.Add("CreditLimit",
System.Type.GetType("System.Double"));
column.DefaultValue = 0;
Click to expand...
// this line does not set the property as expected
column.Caption = "Limit";
Click to expand...
// yet this line does set the property as expected
table.Columns[2].Caption = "Limit";
table.Rows.Add(new object[] { 1, "Jonathan", 23.44 });
table.Rows.Add(new object[] { 2, "Bill", 56.87 });
}
Click to expand...

Interesting, how the caption is set makes a difference.

regards
A.G.
 
column = table.Columns.Add();
column.ColumnName = "CustomerName";
column.DataType = System.Type.GetType("System.String");
column.Caption = "Name";
//CreditLimit
column = table.Columns.Add("CreditLimit",
System.Type.GetType("System.Double"));
column.DefaultValue = 0;
Click to expand...
// this line does not set the property as expected
column.Caption = "Limit";
Click to expand...
// yet this line does set the property as expected
table.Columns[2].Caption = "Limit";
table.Rows.Add(new object[] { 1, "Jonathan", 23.44 });
table.Rows.Add(new object[] { 2, "Bill", 56.87 });
}
Click to expand...

Interesting, how the caption is set makes a difference.
Click to expand...
I must correct myself. How the column is added to the table appears to
make the difference. When the CustomerName column is added as shown
above, the column's Caption property is set to 'Name' just as
expected.

regards
A.G.
 
I've never even considered writing a grid. Lots o' work! However, I did
write a "canvas" control once. It was basically a stripped-down version of
the Windows Workflow designer. Quite a bit of work went into displaying the
boxes that could be placed on the canvas, I can tell you! And the piece I
was most proud of was the "thumbnail navigator," which you use to quickly
move to parts of the canvas that aren't visible.

Writing controls is kind of cool, if you're willing to put in the time. I
applaud those who do.
Click to expand...

Writing a heavyweight control is probably a lot of work.

But it does not even need to be such a thing.

One could also use it for dumping the DataSet to XML.

That is not a big task to write code for.

Arne
 
I am no expert with the grid. But if the DataGrid itself does not use it,
how can it make claim that the field will be used to display as alternate.
It is just a all-purpose property like a Tag. No ?
Click to expand...

The docs for DataColumn states:

"You can use the Caption property to display a descriptive or friendly
name for a DataColumn."

"can use" does not imply "will use".

Arne
 
Actually, I think he was being fast and loose with his pronouns. My take:

"But if the DataGrid itself does not use it [the Caption property of the
DataColumn], how can it [the DataColumn] make claim that the field [the
Caption property (not "field")] will be used to display as alternate."

Isn't English fun?
Click to expand...

I never read the documentation. But can someone show me a place in the
framework that uses the property to display the so called 'caption' ? Sure
you or I can use it to display, I can also use it for something else too.
Click to expand...

A little search showed that it is used for schema generation.

Demo:

using System;
using System.Data;

namespace E
{
public class Program
{
public static void Main(string[] args)
{
DataTable dt = new DataTable("T");
dt.Columns.Add(new DataColumn("C1", typeof(int)));
dt.Columns.Add(new DataColumn("C2", typeof(string)));
dt.WriteXmlSchema(Console.Out);
dt.Columns["C1"].Caption = "This is C1";
dt.Columns["C2"].Caption = "This is C2";
dt.WriteXmlSchema(Console.Out);
Console.ReadKey();
}
}
}

Arne
 
column = table.Columns.Add();
column.ColumnName = "CustomerName";
column.DataType = System.Type.GetType("System.String");
column.Caption = "Name";
//CreditLimit
column = table.Columns.Add("CreditLimit",
System.Type.GetType("System.Double"));
column.DefaultValue = 0;
Click to expand...
// this line does not set the property as expected
column.Caption = "Limit";
Click to expand...
// yet this line does set the property as expected
table.Columns[2].Caption = "Limit";
table.Rows.Add(new object[] { 1, "Jonathan", 23.44 });
table.Rows.Add(new object[] { 2, "Bill", 56.87 });
}
Click to expand...

Interesting, how the caption is set makes a difference.
Click to expand...
I must correct myself. How the column is added to the table appears to
make the difference. When the CustomerName column is added as shown
above, the column's Caption property is set to 'Name' just as
expected.
Click to expand...

Versus...?
 
private void CreateDataTable()
{
DataTable table;
DataColumn column;

table = new DataTable("Customers");

//CustomerID column
column = table.Columns.Add("CustomerID",
System.Type.GetType("System.Int32"));
column.Unique = true;
Click to expand...

column = table.Columns.Add();
column.ColumnName = "CustomerName";
column.DataType = System.Type.GetType("System.String");
column.Caption = "Name";
//CreditLimit
column = table.Columns.Add("CreditLimit",
System.Type.GetType("System.Double"));
column.DefaultValue = 0;
// this line does not set the property as expected
column.Caption = "Limit";
// yet this line does set the property as expected
table.Columns[2].Caption = "Limit";
table.Rows.Add(new object[] { 1, "Jonathan", 23.44 });
table.Rows.Add(new object[] { 2, "Bill", 56.87 });
}


Interesting, how the caption is set makes a difference.
Click to expand...
I must correct myself. How the column is added to the table appears to
make the difference. When the CustomerName column is added as shown
above, the column's Caption property is set to 'Name' just as
expected.
Click to expand...

Versus...?
Click to expand...
the OP's initial problem where setting the Caption property of the
DataColumn object returned by DataTable.Add(string, type) did not
work.

regards
A.G.
 
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