Adding row to Typed datatable in C#

Question

 Below is the code i m using to add row to typed datatable, but it doesnt work. It says use of unassigned local variable.can some one please tell why?

TypedDataTableSchema.TypedDataTableRow r;

r.ID = UserID;

dt.Rows.Add(r);


if i try to assign it 
TypedDataTableSchema.TypedDataTableRow  r = dt.newRow();

Then also it does not work.

Answer 1

Your first attempt will leave the variable r null, so you will get at the line r.ID = UserID; a NullReferenceException.

What error do you receive at the second attempt?

You might have to cast the newRow result:

TypedDataTableSchema.TypedDataTableRow  r = (TypedDataTableSchema.TypedDataTableRow) dt.newRow();

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Ewald - Please remember to mark the replies as answers if they help.

Answer 2

 Thanks, your post helped me a lot.

But cud u please tell how do i use a Typed dataTable as input to a method??

Suppose i have created Datatable schema (in TableSchema.XSD) with table name as "MemberTableschema".
Now i generate a datatable out of it (using the above schema).

i have another method say "Test" which takes this TYped datatable as input.
how should the definition be ? 
Test( DataTable dt) or Test(MemberTableschema dt)?



Also,
The MemberTableschema has follwoing columns:
Name
ID

In this "Test" Method i want to acess the "ID" column's columnName. (to put a filter with distinct criteria on table). How can i get the "ID" column's columnName?

Answer 3

I would use the second option.

public void Test(MemberTableschema dt)
{
  int id = dt.ID;
}

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Ewald - Please remember to mark the replies as answers if they help.

Answer 4

Thats the correct approach, Thank you.

But Ewald,
int id = dt.ID
would the above give me the column name of the ID column??

that means
string colName = dt.Name

will give me "Name" column's columnName?

Answer 5

I was mistaken.

dt.IDColumn will return the datacolumn ID of the datatable, thus dt.IDColumn.Name will return "ID"

dt.Rows[0].ID will return the value in the ID column of the first row in the datatable.

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Ewald - Please remember to mark the replies as answers if they help.