Dear dbutil folks,
I am a newbie to this package. I was really excited because I do not
know much about databases and was hoping that this package could hide most of
the details from me. (Yes, I know I should understand everything, but I simply
do not have the time.)
I spent a pretty good amount of time grappling with how to get this
utility to work with my existing database table and my existing JavaBean. The
issue I was running into was that the column names did not match the JavaBean
property names. I finally found the answer in the forums, but guessing that my
situation is not unique, I was wondering if you might possibly add some
additional documentation to the Example page, at the end of the
"ResultSetHandler Implementations" section. Below I have provided a first
draft. Since I do not know what the submission process is, I am willing to
work with the editor if need be. (I figured I spent some time with this issue
and, if possible, might as well try to save others some time.)
In addition, I am wondering if it might be possible to overload the
BeanHandler constructor so that it also takes a boolean argument. This
argument would be a flag to indicate if the underscore character ought to be
ignored when matching column names to JavaBean properties. This would require
several changes, but the biggest change, I think, would occur in the method
org.apache.commons.dbutils.BeanProcessor.mapColumnsToProperties(ResultSetMetaData
rsmd, PropertyDescriptor[] props). Below I have taken a first cut at the
modified implementation.
thanks,
-markus
http://jakarta.apache.org/commons/dbutils/examples.html
--- START draft of additional documentation
Using the BeanHandler potentially adds a new requirement - it requires
that the names of the column in the database match the property names defined
of the JavaBean. In the above example, that means that if the columns in the
database table "Person" were named "PERSON_ID", "NAME", "FIRST_NAME", and
"LAST_NAME", then the properties of the JavaBean Person.java must be named
"person_id", "name", "first_name", and "last_name". (Note that the case does
not have to match.) Such an example is a real world reality in that many DBAs,
er, encourage a naming schema that contains only capital letters and where each
word is separated by the underscore character.
There are two potential solutions to this issue: (1) re-write the
SELECT statement to use the "AS" SQL keyword, or (2) use an overloaded
constructor of BeanHandler.
So, given a JavaBean with properties "person_id", "name", "first_name",
and "last_name"...
The first solution requires that you change the SQL statement to
"SELECT PERSON_ID AS personId, NAME, FIRST_NAME AS firstName, LAST_NAME AS
lastName FROM Person WHERE name=?". (Note that the AS keyword is not used with
the column named NAME since it matches the property name.)
The second solution requires you to change the line "ResultSetHandler h
= new BeanHandler(Person.class);" to "ResultSetHandler h = new
BeanHandler(Person.class, true);". (Note passing the boolean value true as the
second argument in the constrcutor.)
--- END draft of additional documentation
http://cvs.apache.org/viewcvs.cgi/jakarta-commons/dbutils/src/java/org/apache/commons/dbutils/BeanProcessor.java?rev=1.7&sortdir=down&view=auto
-- START original --
protected int[] mapColumnsToProperties(ResultSetMetaData rsmd,
PropertyDescriptor[] props) throws SQLException {
int cols = rsmd.getColumnCount();
int columnToProperty[] = new int[cols + 1];
Arrays.fill(columnToProperty, PROPERTY_NOT_FOUND);
for (int col = 1; col <= cols; col++) {
String columnName = rsmd.getColumnName(col);
for (int i = 0; i < props.length; i++) {
if (columnName.equalsIgnoreCase(props[i].getName())) {
columnToProperty[col] = i;
break;
}
}
}
return columnToProperty;
}
-- END original --
-- START modified --
protected int[] mapColumnsToProperties(ResultSetMetaData rsmd,
PropertyDescriptor[] props) throws SQLException {
return mapColumnsToProperties(rsmd, props, false);
}
protected int[] mapColumnsToProperties(ResultSetMetaData rsmd,
PropertyDescriptor[] props, boolean ignoreUnderscore) throws
SQLException {
int cols = rsmd.getColumnCount();
int columnToProperty[] = new int[cols + 1];
Arrays.fill(columnToProperty, PROPERTY_NOT_FOUND);
for (int col = 1; col <= cols; col++) {
String columnName = rsmd.getColumnName(col);
String columnNameUnderscoreRemoved = columnName.".replace('_',
'');
for (int i = 0; i < props.length; i++) {
if (columnName.equalsIgnoreCase(props[i].getName())) {
columnToProperty[col] = i;
break;
} // end of IF
else if (
(ignoreUnderscore) &&
(columnNameUnderscoreRemoved
.equalsIgnoreCase(props[i].getName()))
) {
columnToProperty[col] = i;
break;
} // end of ELSE IF
} // end of FOR
}
return columnToProperty;
}
-- END modified --
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