Stripping trailing whitespace from char fields in

What are the possible solutions for stripping the trailing whitespace when mapping char fields in a legacy database?

I see the following options:

Calling .trim() at the point of use (controller, view, etc)
Override property accessors to return .trim()
Using a Hibernate UserType to trim the whitespace

I'm leaning toward overriding the property accessor so that the domain properties remain consistent throughout the application.

回答1:

I had a similar problem and I could not alter the legacy data. I ended up overriding the accessor for the sake of transparency to my fellow developers. I would recommend using a transient field so you don't have to trim the String on every call. However; if you can just clean up the data in the table, create a view, or transfer to a new table I would do that instead.

回答2:

I use a globally mapped Hibernate UserType and it works great (implementation based on http://www.hibernate.org/388.html, but updated for breaking changes to the UserType interface):

package company

import org.hibernate.Hibernate
import org.hibernate.usertype.UserType

import java.sql.PreparedStatement
import java.sql.ResultSet
import java.sql.SQLException
import java.sql.Types

/**
 * Map CHAR(x) types to String: trim when getting and setting the CHAR(x)
 * based on www.hibernate.org/388.html
 */
public class TrimmedString implements UserType {
    public TrimmedString() {
    }

    public int[] sqlTypes() {
        return [Types.CHAR] as int[];
    }

    @SuppressWarnings("unchecked")
    public Class returnedClass() {
        return String.class;
    }

    public boolean equals(Object x, Object y) {
        return (x == y) || (x != null && y != null && (x.equals(y)));
    }

    public Object nullSafeGet(ResultSet inResultSet, String[] names, Object o) throws SQLException {
        String val = (String) Hibernate.STRING.nullSafeGet(inResultSet, names[0]);
        return val == null ? null : val.trim();
    }

    public void nullSafeSet(PreparedStatement inPreparedStatement, Object o, int i) throws SQLException {
        String val = (String) o;
        inPreparedStatement.setString(i, val);
    }

    public Object deepCopy(Object o) {
        if (o == null) {
            return null;
        }
        return new String(((String) o));
    }

    public boolean isMutable() {
        return false;
    }

    public Object assemble(Serializable cached, Object owner) {
        return cached;
    }

    public Serializable disassemble(Object value) {
        return (Serializable) value;
    }

    public Object replace(Object original, Object target, Object owner) {
        return original;
    }

    public int hashCode(Object x) {
        return x.hashCode();
    }
}

global mapping in Groovy.config:

grails.gorm.default.mapping = {
    'user-type'(type: company.TrimmedString, class: String) //map Char(x) columns mapped to string fields as trimmed string
}