Locating row in DataView using primary key

Question

How to locate index of DataViewRow in DataView using primary key
WITHOUT disturbing current sort order (which is not primary key) ?

I have grid control that displays contents of DataView. One row in this
grid is selected. When I have to change sort I wish to retain selected
row under new sort order. So, idea is to get primary key of selected
DataViewRow before new sort order is set and locate that same primary
key under new sort order.

Currently, I have to search DataView manually for specific primary key.
Is there a better way to do this ?

Solution with index positions instead of primary keys will do also.

user1798340 user1798340 · Accepted Answer · 2013-07-29T09:57:15

I think I found most appropriate way to solve this, so if anyone is interested here it is:

DataView's Find method locates row fast using current sort order. Problem with that is that sort key generally does not identify every row with unique sort key. So this to work we have to adapt sort key to be unique for every row. This could be simply accomplished by adding primary key to end of sort expression. That way all sort keys that are not unique will be additionally sorted by their primary key and that will make sort key unique and preserve sort order at the same time. Here's an example:

Let's say we have loaded DataTable:

id  last_name  first_name  date_of_birth
----------------------------------------
11  Rogers     Samuel      1968-08-17
12  Smith      John        1952-12-25
13  Johnson    Bob         1981-03-29
14  Smith      John        1977-02-08
15  Adams      David       1971-09-15
----------------------------------------

// set primary key for DataTable

table.PrimaryKey = new DataColumn[] { table.Columns[ "id" ] };

// create first sorting order by last and first name
// but make sort unique by adding primary key at end

DataView view1 = new DataView( table );
view1.Sort = "last_name, first_name, id";

// create second sorting order by date of birth and again
// make sort unique by adding primary key at end

DataView view2 = new DataView( table );
view2.Sort = "date_of_birth, id";

// get DataRow of DataTable with primary key 14

DataRow row = table.Rows.Find( 14 );

// using data from DataRow find matching sort key

// be aware that Find method of DataView could return -1
// if DataView has filter set that hides row you search

int index_in_view1 = view1.Find( new Object[] { row[ "last_name" ],
                                                row[ "first_name" ],
                                                row[ "id" ] } );

int index_in_view2 = view2.Find( new Object[] { row[ "date_of_birth" ],
                                                row[ "id" ] } );

If anyone has any objection to this solution I would really be interested to hear.

Locating row in DataView using primary key

1 Answers