public class RowMatch extends ExprEval implements java.io.Serializable
RowMatch is used to apply in-memory a qualifying
expression to rows in memory. The user specifies a SQL
expression.
A RowMatch may be used stand-alone or used a qualifying RowMatch for
a ViewObject. To use it stand-alone, one would create a RowMatch.
Then, to see if a Row qualifies, one would invoke
rowQualifies(Row). Here is an example:
RowMatch rowMatch = new RowMatch("Deptno = 30");
if (rowMatch.rowQualifies(row))
{
System.out.println("We have a row whose Deptno is 30");
}
To use a RowMatch for a ViewObject, invoke
ViewObject.setRowMatch(RowMatch). Rows will be
qualified in-memory.
RowMatch differs from the where-clause of a database
query statement mainly in that one should use row's attribute names
as opposed to the database column names. Note that database column
names are by default case-insensitive, while attribute names are
case-sensitive.
Hence, to qualify for EmpView rows whose Deptno attribute value is 30, one can use the following where-clause in his query statement:
DEPTNO = 30
To use the same qualification in-memory, one would create a
RowMatch with
Deptno = 30
Where-clause qualfication only applies to rows already exsiting
in the database table. RowMatch will apply to
rows as they are read from database query as well. Additionally,
RowMatch is applied to rows that are created because
of view link consistency.
View link consistency allows a RowSet to see
new rows (unposted) created by another RowSet. Internally,
when a new row is created by the other RowSet and the row's primary key
is set, the original RowSet (if view link cosnsistency is on)
receives an event indicating a new row has been created. This RowSet
creates a row and inserts it in its collection. Before this copy
row is inserted, it is tested against the view object's RowMatch.
Only if the row qualifies will it be inserted.
If a qualification can be expressed in a query's where-clause, one should use the where-clause, because database will skip unqualifying rows. If one relies solely on the RowMatch for in-memory qualification, he may incur unnecessary performance overhead, because rows will be read from database query and formed in memory.
Unlike a where-clause, a RowMatch can evaluate expression involving transient attributes and not-yet-posted attribute values.
RowMatch is able to handle where-clause parameters in its expression. Assuming oracle number binding style for example, one can specify the following RowMatch:
RowMatch rowMatch = new RowMatch("Deptno = :1");
ViewObject vo;
Row row;
...
vo.setRowMatch(rowMatch);
vo.executeQuery();
// When evaluating each row for qualification, the where-clause
// parameter of index 0 (where-clause param indices are 0 based)
// will be used to see if it equals the Deptno attr value.
while ((row = vo.next()) != null)
{
System.out.println("This row's Deptno is " + vo.getWhereClauseParam(0));
}
RowMatch is also able to access variable values. To do so, one would
use ":
RowMatch rowMatch = new RowMatch("Deptno = :myVariable");
When the RowMatch is used for a ViewObject, the ViewObject's
variable manager will be asked to return the value of the variable.
If the RowMatch is being used stand-alone, the row's owner
(through the getStructureDef() call on the
Row interface) is asked for the variable value.
In this case, the owner object must implement the
oracle.jbo.RowMatchBindValueSupplier interface.Row,
RowMatchBindValueSupplier,
Serialized FormExprEval.Privilege, ExprEval.TrustMode, ExprEval.TypeCheckedModeEXPR_KEY_ADF, EXPR_KEY_ADFBCSESSION, EXPR_KEY_ADFCONTEXT, EXPR_KEY_ADFCRITERIAROW, EXPR_KEY_ADFCURRENT_DATE, EXPR_KEY_ADFCURRENT_DATETIME, EXPR_KEY_ADFCURRENT_DBDATE, EXPR_KEY_ADFCURRENT_DBDATETIME, EXPR_KEY_ADFDBTRANSACTION, EXPR_KEY_ADFERROR, EXPR_KEY_ADFSELF, EXPR_KEY_ADFSOURCE, EXPR_KEY_ADFUTIL, EXPR_KEY_ADFVIEWOBJECT, EXPR_KEY_GROOVY_OUT, EXPR_KEY_WEBSERVICES, EXPR_STYLE_GROOVY, EXPR_STYLE_JAVA, EXPR_STYLE_SQL, INTERNAL_MARKER_METHOD, INTERNAL_MARKER_METHOD_NAME, INTERNAL_UNTRUSTED_SCRIPT_PREAMBLE, INTERNAL_UNTRUSTED_SCRIPT_PREAMBLE_LINES, mTypeCheckedLogger, NULL_VALUE, RESERVED_EXPR_KEY_ADFBCSESSION, RESERVED_EXPR_KEY_ADFCUSTOMGROOVY, RESERVED_EXPR_KEY_ADFGLOBALUTILITY, RESERVED_EXPR_KEY_SERVICERESOURCECONTAINERPATH, TRUSTEDSCRIPTLOG, UNTRUSTEDSCRIPTLOGRESERVED_VAR_AGG_AVG, RESERVED_VAR_AGG_COUNT, RESERVED_VAR_AGG_MAX, RESERVED_VAR_AGG_MIN, RESERVED_VAR_AGG_SUM, RESERVED_VAR_AGGVAL_PREFIX, RESERVED_VAR_STRUCTURE_DEFRESERVED_VAR_VALUE| Constructor and Description |
|---|
RowMatch() |
RowMatch(java.lang.String whereClause) |
RowMatch(java.lang.String whereClause,
JIParserHelper ph) |
| Modifier and Type | Method and Description |
|---|---|
java.lang.String |
getWhereClause() |
boolean |
objQualifies(ExprValueSupplier valSupplier) |
boolean |
rowQualifies(Row row) |
void |
setWhereClause(java.lang.String text)
Deprecated.
since 12.2.1.1.0
Clients should create a new RowMatch instead.
|
compileOperations, equals, evaluate, evaluate, evaluate, evaluate, evaluateForRow, evaluateForRow, getCacheHitCount, getCacheMissCount, getExecuteCount, getExprDef, getExprIdentifier, getExprMethodVal, getExprStr, getMethodKind, getOptimizedExecuteCount, getParseCount, getParsedExpr, getRowVal, getTrustedExprPropertyNames, invokeFunction, invokeFunction, setRowVal, validatepublic RowMatch()
public RowMatch(java.lang.String whereClause)
public RowMatch(java.lang.String whereClause,
JIParserHelper ph)
public java.lang.String getWhereClause()
public void setWhereClause(java.lang.String text)
public boolean rowQualifies(Row row)
public boolean objQualifies(ExprValueSupplier valSupplier)