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.NET Forum / Languages / C# / January 2008DataTable.Select - Thread.CurrentThread.CurrentCulture - String.Format
Hi NG, in my application a <myDataTable>.Select fails with "Syntax error in the expression." It took me a while, isolate the cause to this: To select some datarows from a data table I am using a select sting like "selectStr = String.Format("x >= {0}", aDoubleVar)". The Thread.CurrentThread.CurrenCulture is set to "en-US" where the Thread.CurrentThread.CurrentCulture.NumberFormat.CurrencyDecimalSeparator is a '.' as expected. BUT.... debugging my selectStr it turned out to be "x>= 2,14" ! After a while I had the Idea to check ControlPanel->Regional and LanguageOptions and YES, the user has changed the decimal seperator. So I currently looks like - String.Format uses the ControlPanel Settings "," - The DataTable uses Thread.CurrentThread.CurrentCulture "." Is this a BUG in the Framework, or in my HEAD? Is there something I missed? Any help or hint on this subject is very appreciated. Regards Rainer Queck I don't know much about DataTable(I've always steered fairly clear of DataSet), but if this was a regular SqlCommand (etc) I would be adding a parameter with .Value = aDoubleVar - that way, you don't need to worry about formatting, plus it is injection safe (think "Bobby Tables"...). However, if you /must/ use string concatenation, then you should ensure that the format is in the known, fixed, expected format of whatever you are talking to. It is *entirely reasonable* for the user to use their local (or /locale/) formats and separators, and your code shouldn't rely on this. This should be used for displaying data to the user, not exchanging data between systems. You could try passing CultureInfo.InvariantCulture as the first argument to string.Format (although you might need a more specific format...). But I stress; the most reliable option is using parameters. This is a /similar/ (but unrelated) problem to using the default encoding / endianness when exchanging text as binary; when talking between systems it is best to agree in advance what formats to use. Marc Hello Marc, thanks for helping me again! >I don't know much about DataTable(I've always steered fairly clear of > DataSet), but if this was a regular SqlCommand (etc) I would be adding > a parameter with .Value = aDoubleVar - that way, you don't need to > worry about formatting, plus it is injection safe (think "Bobby > Tables"...). Yes, it would be preferable to use aDoubleVar parameter. Unfortunately in order to do a select ( which is not a regualr SqlCommand ) on a dataTable (see DataTable.Select) I must use a string, unless there I a feature in DataTable I havn't met yet. > However, if you /must/ use string concatenation, then you should > ensure that the format is in the known, fixed, expected format of <snip> Well, the word "expected" in my question results of the information I retreave from Thread.CurrentThread.CurrentCulture (en-US at that time) as I set the breakpoint at the codeline in question. I in the meanwhile also looked at "Thread.CurrentThread.CurrentCulture.Numberformat.CurrentDecimalSeperator" which also showed ".". Still the String.Format gave me a "," ! <snip> > whatever you are talking to. It is *entirely reasonable* for the user > to use their local (or /locale/) formats and separators, and your code > shouldn't rely on this. This should be used for displaying data to the > user, not exchanging data between systems. You could try passing > CultureInfo.InvariantCulture as the first argument to string.Format > (although you might need a more specific format...). That "sounds" like a solution. I am a little hesitant, because (what I have not mentioned yet) on of the requirements to my application is, that the used language must be changable at runtime. Also it is a multithreaded application (might be, that I still have some lacks here). Would it be ok to only set Thread.CurrentThread.CurrentUICulture to what ever the user wants and have the Thread.CurrentThread.CurrentCulture internaly set to CultureInfo.InvariantCulture? Would this also work if Parameters entered by the user in his Culture are processed by methods where their thread is set to InvariantCulture? Regards Rainer I wouldn't set the culture the invariant - I'd (as indicated) *use* the invariant culture when I am doing system-to-system calls - i.e. string.Format(CultureInfo.InvariantCulture, "foo", bar). Note that there can be issues messing with culture while forms are displayed; they don't like that much... a simpler option might be to save the new culture in a settings file, and restart the app? (I believe that Application has a Restart method or similar). Also; re supplying proper parameters - I don't really know (not having done it myself), but is this not the GetFillParameters method on the data-adapter? Marc Hi Mark, >I wouldn't set the culture the invariant - I'd (as indicated) *use* > the invariant culture when I am doing system-to-system calls - i.e. > string.Format(CultureInfo.InvariantCulture, "foo", bar). Yes, that is what I am currently doing (ref my other answer/question). > Note that there can be issues messing with culture while forms are > displayed; they don't like that much... a simpler option might be to > save the new culture in a settings file, and restart the app? (I > believe that Application has a Restart method or similar). It surely would be better, to set the culture and the stop/restart the application. Unfortunately it is a request from my customer, that the app must be able to switch rultures at runtime. Acutally this is working quite good. I used the method pointed out in http://dzaebel.net/LocalizeRuntime.htm by Frank Dzaeble. > Also; re supplying proper parameters - I don't really know (not having > done it myself), but is this not the GetFillParameters method on the > data-adapter? You are right, but I dont have a data-adapter, since I am working with a "standalone" typed DataSet. As mentioned above, I am already following your suggestion, and am using CultureInfo.InvariantCulture to do my String.Format on selectStr generation. It seems to be working fine, which leads me to the thought, that DataSets are using CultureInfo.InvariantCulture internaly as well. If someone could state this true, I can replace "seems to" with "is" ;-) Regards Rainer Hi Marc, >You could try passing > CultureInfo.InvariantCulture as the first argument to string.Format > (although you might need a more specific format...). What kind of a Culture is a DataTable using for example on a select? Is it possible, that it usese the "InvariantCulture" as well? If that is the case, I could get rid of my problem by following your suggestion. If not.... :-( Regards Rainer Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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