Does anyone know how to make nhibernate map char(n) columns to a string without adding trailing whitespace?

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Say if you have a char(5) column in the db and you have "ABC" in there, if you map this column to a string property you will find nhibernate will map it as "ABC__" where the underscores represent whitespace of some sort (I haven't checked what ascii code it is)

For a long time now we just solved this problem by changing the column to varchar and trimming all the entries in the DB. It would be better if there was a solution that let us keep the columns as char(n) (if only to save us some work)

I guess I could try trimming on get and padding on set, but that doesn't strike me as the greatest solution.

So, is there some nice way to configure nhibernate to read a char(n) column into a string without it reading in extra whitespace?

Thanks!

Yes and no. You can use a formula property on a field tag to set the value to RTrim(myCharField) but then it won't be bound. That is to say, any changes you make to the field won't be saved to the database.

I don't really see why this is a problem though. If you're designing your application with a data layer it should be simple enough to add a trim call to the getter method of the entity's properties before returning shouldn't it?

How can I trim string property datatypes from database char , You can create an implementation of NHibernate.UserTypes.IUserType that will trim the whitespace when fetched from the In your fluent mapping, you just add . not want to trim both leading and trailing whitespace, as Trim() will do. modify the database, you can create a view that trims the columns. In every training class we do, I learn stuff from students. Here’s last week’s surprise. Create a temp table, and put in a value with trailing spaces. Then query for it using the = and <> operators, using different numbers of trailing spaces: [crayon-5f542c3e27e2c509093702/] SQL Server simply ignores the trailing spaces: The mind-blowing part to

I'm not sure which database you are using, but we use iSeries DB2, and we have the same issue with trailing whitespaces. We created a custom user type to "trim" the values from these columns: TrimmedUser.cs gist

This works because iSeries DB2 doesn't consider trailing whitespace when doing a string comparison (i.e., 'MYSTRING' equals 'MYSTRING '). If this isn't true for your particular database, you could probably handle that in the "NullSafeSet" method, by right padding with the whitespace character used by your database.

8 Ways to use the features of your database with Hibernate, Hibernate can do a lot more than just map simple database tables. 3 Stored Procedures; 4 Database columns with generated values; 5 Map SQL expressions You can map a view in the same way as any database table. trim(String s): removes leading and trailing whitespaces from the given String s; length(String s) :� In-between space (where n is the position of the problematic character in the text string): =CODE(MID(A1, n, 1))) And then, supply the returned character code to the TRIM(SUBSTITUTE()) formula discussed above. For example, if the CODE function returns 9, which is the Horizontal Tab character, you use the following formula to remove it:

Here's an updated version of Andy's gist:

public class TrimmedString : NHibernateFactoryType<string>
{
    public override SqlType[] SqlTypes => new[] { new SqlType(DbType.AnsiStringFixedLength) };

    public override object NullSafeGet(DbDataReader rs, string[] names, ISessionImplementor session, object owner)
    {
        var str = (string)NHibernateUtil.String.NullSafeGet(rs, names[0], session);
        return str?.Trim();
    }

    public override void NullSafeSet(DbCommand cmd, object value, int index, ISessionImplementor session)
    {
        value = ((string)value)?.Trim();  //Not really necessary
        NHibernateUtil.String.NullSafeSet(cmd, value, index, session);
    }
}

About This Book - NHibernate in Action, NET developers have had no such luxury for learning NHibernate. We also don't expect that you've worked with any object/relational mapping framework Chapter 5 delves into using NHibernate to get tight control over database transactions. performance problems, discussing the n+1 selects problem and caching. J N 5 5 1 1 2 2 B The nearest I have got is the right function, but it brings over the preceeding characters, and I need each character in its own cell. Hopefully I could copy/paste a formula and change the reference for each cell value, i.e. 1 would return J, 2 = N, 3 = 5, 4 = 5 etc. Thanks for your help!

Chapter 6. Collection Mapping, Collections may contain almost any other NHibernate type, including all basic types, All collection types except ISet and bag have an index column - a column that maps to By example, a <set> element is used for mapping properties of type ISet. No null values may be contained in a dictionary, set or list (unless using� The first is called “NC_000001.10 Genome Reference Consortium Human Build 37 (GRCh37), Primary_Assembly”, and is the one I need, and the second one is called just “NT_004610.19” and it’s the one that the script prints. Do you know how to make the script print the “right” coordinates (at least,the ones I need)?

Data Types — CUBRID 8.4.4 documentation, Attributes declared as exact numeric data types always have fixed precision When character string which is shorter than n is stored, whitespace If a user change any LOB file without using CUBRID API or CUBRID tools, data consistency is LOB type columns, an error is likely to occur, as the mapping of LOB Locator� delete all occurrences of the space character, code 0x20. delete all horizontal space, including the horizontal tab character, "\t" delete all whitespace, including newline, "\n" and others; The right tool for the job. If sed it not a requirement for some hidden reason, better use the right tool for the job.

(I do not manually enter the data, it is a formula that I do not wish to delete.) I know I can manually move the data that the line is pulling to make it stop on the last month, but I have a graph for 36 different departments and that's a pain to have to manually adjust 36 graphs each month.

Comments
  • the trim to the get isn't quite enough, sometimes if you read the property into some user editable field like a datagridview, the trimmed values make their way back into set and if the session gets flushed useless update statements get created
  • I was just thinking I could just make sure to pad all values coming into the set back to what it is in the first place to prevent that, though. I was just hoping that there was some magical way to configure things that would stop me from having to do this every time.
  • "if the session gets flushed useless update statements get created" Unless there's something unusual about your application where entities are routinely saved automatically (as opposed to some button click by the user) the number of useless updates is going to be fairly insignificant. The user would have to open up the entity, make no changes and click save. I don't believe that happens very often.
  • Sometimes we've made grids with quite a lot of entries on them. One had a few thousand items in there. All the useless update statements caused quite a delay... I guess we can design the screens around this problem.. but I'd rather just not have those useless update statements
  • Ah I see. Yeah it sounds like all you're stuck with is stuff you don't really want to do. Since all options are somewhat painful I would at least recommend you choose the one that cleans up your database (switch char fields to varchar)