jimm.datavision
Class UserColumn

java.lang.Object
  java.util.Observable
      jimm.datavision.Expression
          jimm.datavision.UserColumn

All Implemented Interfaces:

java.util.Observer, Draggable, Identity, Nameable, Selectable, Writeable

public class UserColumn
extends Expression
implements Selectable

A user column is an arbitrary expression inserted into the SQL query and retrieved as a column value. It may contain database column values, parameters, special values, strings, or numbers. It can't contain formulas because their values may be undefined when the query is run.

When used by a query, the following substitutions are made withing the userString of a user column:

• {table_name.column_name} is replaced by the column name table_name.column_name.
• {%special_value_name} is replaced by a special value (report title, report run date, page number, or record number).
• {?id_number} is replaced by a parameter value (string, number, or date).

Author:

Jim Menard, jimm@io.com

Field Summary

static int

MAX_DISPLAY_NAME_LENGTH

Fields inherited from class jimm.datavision.Expression

exceptAfter, expr, id, name, observedContents, report

Constructor Summary

UserColumn(java.lang.Long id, Report report, java.lang.String name)
Constructor.

UserColumn(java.lang.Long id, Report report, java.lang.String name, java.lang.String evalString)
Constructor.

Method Summary

java.lang.String	designLabel()
java.lang.String	dragString() Returns the string used to identify the object when dragging it.
java.lang.String	fieldTypeString() Returns the string used to create a field of the appropriate type.
java.lang.String	formulaString()
java.lang.String	getDisplayName()
java.lang.String	getSelectString(SQLQuery query) Returns the string used by a SQL query to select this object.
java.lang.String	getSortString(SQLQuery query) Returns the string used as the name/value of this selectable in a SQL ORDER BY clause.
Table	getTable() Returns the table to which this selectable belongs; may be null.
java.lang.Object	getValue(Report report) Returns the current value.
Selectable	reloadInstance(DataSource dataSource) Returns a (possibly new) instance of this selectable object.
java.lang.String	toString() Returns this user column's SQL text as entered by the user.
void	writeXML(XMLWriter out) Writes this expression as an XML tag.

Methods inherited from class jimm.datavision.Expression

columnsUsed, displayToExpression, expressionToDisplay, finalize, getEditableExpression, getExpression, getId, getName, refersTo, refersTo, refersTo, setEditableExpression, setExpression, setName, startObservingContents, stopObservingContents, update, userColumnsUsed, writeAdditionalAttributes, writeXML

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface jimm.datavision.Selectable

getId

Field Detail

MAX_DISPLAY_NAME_LENGTH

public static final int MAX_DISPLAY_NAME_LENGTH

See Also:

Constant Field Values

Constructor Detail

UserColumn

public UserColumn(java.lang.Long id,
                  Report report,
                  java.lang.String name)

Constructor.

Parameters:

id - the unique identifier for the new user column; if null, generate a new id

report - the report containing this user column

name - the user column name

UserColumn

public UserColumn(java.lang.Long id,
                  Report report,
                  java.lang.String name,
                  java.lang.String evalString)

Constructor. If id is null, generates a new id number. This number is one higher than any previously-seen id number. This does not guarantee that no later user column will be created manually with the same id number.

Parameters:

id - the unique identifier for the new user column; if null, generate a new id

report - the report containing this user column

name - the user column name

evalString - the string to evaulate at runtime.

Method Detail

getValue

public java.lang.Object getValue(Report report)

Description copied from interface: Selectable

Returns the current value. May only be valid during a report run.

Specified by:

getValue in interface Selectable

Parameters:

report - a report

Returns:

the current value

fieldTypeString

public java.lang.String fieldTypeString()

Description copied from interface: Selectable

Returns the string used to create a field of the appropriate type.

Specified by:

fieldTypeString in interface Selectable

Returns:

a string useable by Field.create

See Also:

Field.create(java.lang.Long, jimm.datavision.Report, jimm.datavision.Section, java.lang.String, java.lang.Object, boolean)

getSelectString

public java.lang.String getSelectString(SQLQuery query)

Description copied from interface: Selectable

Returns the string used by a SQL query to select this object.

Specified by:

getSelectString in interface Selectable

getSortString

public java.lang.String getSortString(SQLQuery query)

Description copied from interface: Selectable

Returns the string used as the name/value of this selectable in a SQL ORDER BY clause. This may be the same as the select string returned by getSelectString.

Specified by:

getSortString in interface Selectable

Returns:

a string used when creating the ORDER BY clause

See Also:

Selectable.getSelectString(jimm.datavision.source.sql.SQLQuery)

getTable

public Table getTable()

Description copied from interface: Selectable

Returns the table to which this selectable belongs; may be null.

Specified by:

getTable in interface Selectable

Returns:

the table to which this selectable belongs; may be null

getDisplayName

public java.lang.String getDisplayName()

Specified by:

getDisplayName in interface Selectable

dragString

public java.lang.String dragString()

Description copied from interface: Draggable

Returns the string used to identify the object when dragging it.

Specified by:

dragString in interface Draggable

Specified by:

dragString in class Expression

Returns:

a string used to identify the object when dragging it

designLabel

public java.lang.String designLabel()

Specified by:

designLabel in class Expression

formulaString

public java.lang.String formulaString()

Specified by:

formulaString in class Expression

reloadInstance

public Selectable reloadInstance(DataSource dataSource)

Description copied from interface: Selectable

Returns a (possibly new) instance of this selectable object. Used when we are reestablishing or resetting a connection to a database. The instance returned may or may not be the same object as this one.

Specified by:

reloadInstance in interface Selectable

toString

public java.lang.String toString()

Returns this user column's SQL text as entered by the user.

Overrides:

toString in class java.lang.Object

writeXML

public void writeXML(XMLWriter out)

Description copied from class: Expression

Writes this expression as an XML tag.

Specified by:

writeXML in interface Writeable

Specified by:

writeXML in class Expression

Parameters:

out - a writer that knows how to write XML