MySQL Bugs: #62094: char field mapped to System.String of MaxLength=3*len(char) in .NET/Connector

Bug #62094	char field mapped to System.String of MaxLength=3*len(char) in .NET/Connector
Submitted:	5 Aug 2011 14:39	Modified:	29 Sep 2011 20:52
Reporter:	River D	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / NET	Severity:	S2 (Serious)
Version:	6.4.3	OS:	Windows
Assigned to:	Fernando Gonzalez.Sanchez	CPU Architecture:	Any
Tags:	.net/connector, char, maxlength, System.String

Description:
Suppose we have a MySQL table with a Char field, fldChar, of length L, when we put this table into a Dataset form in Visual studio 2010.net to create a related tableadapter, then the field object fldChar in the tableadapter will have a MaxLength of 3*L

How to repeat:
1. Create a table, say tbltest, with a char field fldChar, set its length to 1.
2. Create a Dataset Form, Dataset1, in VS 2010.NET
3. Drag tbltest onto Dataset1, to create a tbltestTableAdapter class.
4. You will find the related field fldChar in tbltestTableAdapter have a MaxLength of 3, NOT 1 as expected.

Suggested fix:
No

Please, send the output of:

show create table  tbltest\G
show variables like 'char%';

from your MySQL server. I wonder if utf8 character set is used.

Hi, Valeriy Kravchuk,

Apologize for late response.
It is sure I am using utf8 character set.
But I wonder this can cause problems in .NET programming.

Ex: I want to restrict MaxLength of all TextBoxes on a form by means of MaxLength of the bound text programmatically as follows:

private void setMaxLength()
{
	foreach (Control c in this.Controls)
	{
		if (c is TextBox)
		{
			TextBox t = (TextBox)c;
			string fld = t.DataBindings["text"].BindingMemberInfo.BindingField;
			if (dataSet1.t1.Columns[fld].DataType.ToString() == "System.String")
				t.MaxLength = dataSet1.t1.Columns[fld].MaxLength;
		}
	}
}

Since the varchar and char fields in MySQL are both reflected to a column DataType of "System.String", the corresponding MaxLength of the TextBox will be set to 3 times of the field length in MySQL.

Any suggestions?

Sorry,

the corresponding MaxLength of the TextBox whose Text attribute is bound with a char field will be set to 3 times of the field length in MySQL.

Thank you for your bug report. This issue has already been fixed in the latest released version of that product, which you can download at

  http://www.mysql.com/downloads/

This was fixed in releases 6.2.6, 6.3.8, 6.4.4.

Added to changelog for 6.2.6, 6.3.8, 6.4.4: 

When creating a tableadapter through a Dataset form in Visual Studio,
the MaxLength of the field for a CHAR column could be set to 3 times
the length of the table column. Although this many bytes could be
needed to hold a UTF-8 character value, the length value was not
appropriate for restricting the length of a TextBox.