package jimm.datavision.field;
import jimm.datavision.*;
import jimm.datavision.gui.FieldWidget;
import jimm.datavision.gui.UserColumnWidget;
import jimm.datavision.gui.SectionWidget;
import java.util.Collection;
import java.util.Observer;
import java.util.Observable;
/**
* A user column field represents a user column, which in turn holds some SQL
* that is put in the SELECT clause of a query. The value of a user column
* field holds a {@link UserColumn} object. (In the XML, the user column
* field's value is the id of the user column.)
*
* @author Jim Menard, <a href="mailto:jimm@io.com">jimm@io.com</a>
*/
public class UserColumnField extends Field implements Observer {
protected UserColumn usercol;
/**
* Constructs a user column field with the specified id in the specified report
* section whose {@link UserColumn}'s id is <var>value</var>.
*
* @param id the new field's id
* @param report the report containing this element
* @param section the report section in which the field resides
* @param value the id of a user column
* @param visible show/hide flag
*/
public UserColumnField(Long id, Report report, Section section, Object value,
boolean visible)
{
super(id, report, section, value, visible);
usercol = report.findUserColumn(value);
usercol.addObserver(this);
}
protected void finalize() throws Throwable {
usercol.deleteObserver(this);
super.finalize();
}
public void update(Observable o, Object arg) {
setChanged();
notifyObservers(arg);
}
public FieldWidget makeWidget(SectionWidget sw) {
return new UserColumnWidget(sw, this);
}
/**
* Not really used; we drag user columns, not user column fields.
*/
public String dragString() {
return typeString() + ":" + usercol.getId();
}
/**
* Returns the user column.
*
* @return the user column
*/
public UserColumn getUserColumn() { return usercol; }
/**
* Sets the user column.
*
* @param newUsercol the new user column
*/
public void setUserColumn(UserColumn newUsercol) {
if (usercol != newUsercol) {
usercol.deleteObserver(this);
usercol = newUsercol;
usercol.addObserver(this);
setChanged();
notifyObservers();
}
}
public String typeString() { return "usercol"; }
public String designLabel() { return usercol.designLabel(); }
public String formulaString() { return usercol.formulaString(); }
public boolean refersTo(Field f) {
return usercol.refersTo(f);
}
public boolean refersTo(Parameter p) {
return usercol.refersTo(p);
}
/**
* This override returns <code>true</code> if this user column is in a
* detail section. We don't really know that this user column returns
* a number, so we'll err on the side of allowing aggregation.
*
* @return <code>true</code> if this field can be aggregated
*/
public boolean canBeAggregated() {
// Section can be null during dragging.
return section != null && section.isDetail();
}
/**
* Returns the value of this field. For user column fields, this is the
* value generated by evaluating the {@link UserColumn}.
*
* @return the result of evaluating the usercol
*/
public Object getValue() { return getReport().columnValue(usercol); }
/**
* Returns a collection of the columns used in the user column. This is used
* by the report's query when it is figuring out what columns and tables
* are used by the report. Calls {@link UserColumn#columnsUsed}.
*
* @see jimm.datavision.source.Query#findSelectablesUsed
*/
public Collection columnsUsed() {
return usercol.columnsUsed();
}
}