Bug 666 - DataColumn Expressions and Column order
Summary: DataColumn Expressions and Column order
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Data ()
Version: 2.10.x
Hardware: Macintosh Mac OS
: High major
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2011-09-07 13:07 UTC by Dominique NORMAND
Modified: 2011-09-13 08:18 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Dominique NORMAND 2011-09-07 13:07:24 UTC
A DataColumn expression cannot reference columns that are defined after (higher ordinal #) the column the expression is assigned to.
We can create all the column and define expression afterward, but then the DataTable.Clone fails crashes.

I think the _compiledExpression should be evaluated only if needed. Either when adding the first row or when accessing the data of that column.

Step to Recreate the defect:

Case 1:

System.Data.DataTable table1 = new System.Data.DataTable("Table1") ;

System.Data.DataColumn c1 = table1.Columns.Add("c1", typeof(string), "'hello ' + c2") ; /* Causes Exception */
System.Data.DataColumn c2 = table1.Columns.Add("c2") ;

Case 2:

System.Data.DataTable table1 = new System.Data.DataTable("Table1") ;

System.Data.DataColumn c1 = table1.Columns.Add("c1") ;
System.Data.DataColumn c2 = table1.Columns.Add("c2") ;

c1.Expression = "'hello ' + c2";

System.Data.DataTable t2 = table1.Clone(); /* Causes Exception */
Comment 1 Rolf Bjarne Kvinge [MSFT] 2011-09-13 08:18:01 UTC
Case 1 doesn't work on windows (it throws an EvaluateException), so our behaviour there is correct.

Case 2 is fixed in 3646906. It will probably reach the next MonoTouch beta.