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PONon-String values in DataGridViewComboBoxColumn causing DataErrors in DataGridView
 

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  1. PONon-String values in DataGridViewComboBoxColumn causing DataErrors in DataGridView
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    <p>I have a programmtically filled DataGridView with some <code>DataGridViewComboBoxColumn</code> entries. These ComboBoxes hold custom types that have their <code>ToString()</code> overwritten to hide their internal guts from the user.</p> <p>The Problem: whenever I change the value of the ComboBox and select another cell, the <code>CellValidating</code> is called, the FormattedValue is the string-result of my custom FooBar.ToString() (should be ok). In <code>CellEndEdit</code>, the ValueType is suddenly a string and not my custom type anymore and I get error either watching row.Cell-Member in VS or doing a mouse-over on the changed cell (translated from german):</p> <p>"DataGridView-Exception: <code>System.ArgumentException</code>: The <code>DataGridViewComboBoxCell</code>-Value is invalid. Handle the DataError-Exception to replace this dialog"</p> <p>This is how the column is constructed - colFoo is a <code>DataGridViewComboBoxColumn</code>:</p> <pre><code> dataGridInstance.Columns[1].CellTemplate.Value = new FooBar("bla", 31); dataGridInstance.Columns[1].CellTemplate.ValueType = typeof(FooBar); foreach (FooBar foo in FooBarArray) colSymbol.Items.Add(sym); </code></pre> <p>The Grid gets filled like this:</p> <pre><code> foreach (FooLine line in SomeFooLineArray) { DataGridViewRow newRow = ((DataGridViewRow)dataGridInstance.RowTemplate.Clone()); newRow.Cells[1].Value = line.Foo; // FooBar instance field dataGridInstance.Rows.Add(newRow); } </code></pre> <p>Any experiments in <code>CellValidating</code> or <code>CellFormatting</code> failed, I always get this message. </p> <p>How can I add custom types into the existing <code>DataGridView</code> without overwriting too much? Almost every other Component (including dropboxes) supports custom types just fine, only the step of copying the value from the Combo to the grid seams to be the problem.</p> <p>As asked, the FooBar-implementation looks like this:</p> <pre><code> internal class FooBar { private readonly int id; private readonly string name; internal FooBar(string n, int i) { id = i; name = n; } public override string ToString() { return name; } } </code></pre> <p>It does a little bit more, but that is the meaningful functionality encapsulated.</p>
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    1. USCoder02
    1. USCoder02
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    1. COcan you paste the overriden ToString() code that you have in question..
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      1. USMethodMan
    2. COImplementation added above.
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      1. USCoder02
    3. COWell, after spending more time in investigation, I found out that this is indeed no unknown problem - a solution with custom data bound to the grid was proposed [here (Google Groups)](http://groups.google.com/group/microsoft.public.dotnet.framework.windowsforms.databinding/browse_thread/thread/4b7fe5a2274e0d46?pli=1). Sadly, it does not work for me because I am not using a data source but filling the combobox myself. I got around the issue using strings again and making sure that there are no duplicate FooBar instances with the same `Name` used.
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      1. USCoder02
 

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