Defines an EventFilter for a monitored item. 更多...
| EventFilter (const QOpcUaMonitoringParameters::EventFilter & rhs ) | |
| QList<QOpcUaSimpleAttributeOperand> | selectClauses () const |
| QList<QOpcUaSimpleAttributeOperand> & | selectClausesRef () |
| void | setSelectClauses (const QList<QOpcUaSimpleAttributeOperand> & selectClauses ) |
| void | setWhereClause (const QList<QOpcUaContentFilterElement> & whereClause ) |
| QList<QOpcUaContentFilterElement> | whereClause () const |
| QList<QOpcUaContentFilterElement> & | whereClauseRef () |
| const QVariant | operator const QVariant () |
| QOpcUaMonitoringParameters::EventFilter & | operator<< (const QOpcUaContentFilterElement & whereClauseElement ) |
| QOpcUaMonitoringParameters::EventFilter & | operator<< (const QOpcUaSimpleAttributeOperand & selectClauseElement ) |
| QOpcUaMonitoringParameters::EventFilter & | operator= (const QOpcUaMonitoringParameters::EventFilter & rhs ) |
| bool | operator== (const QOpcUaMonitoringParameters::EventFilter & rhs ) const |
An event filter is required for monitoring events on the server. It consists of
select
clauses and a
where
子句。
The
select
clauses are used to specify the data the user wants to receive when an event occurs. It consists of
QOpcUaSimpleAttributeOperand
simple attribute operands which select attributes of child nodes of an event type, for example the value attribute of the "Message" property of BaseEventType.
The
where
clause is used to restrict the reported events by matching against certain criteria. Several operators and four different operand types allow filtering based on the values of the attributes of the child nodes of an event type.
Filters can be constructed using the setter or the streaming operator. Streaming a
QOpcUaSimpleAttributeOperand
into an event filter adds a new
select
clause to the filter, a
QOpcUaContentFilterElement
is appended to the
where
clause. A content filter element can be constructed by streaming operands of the types
QOpcUaLiteralOperand
,
QOpcUaElementOperand
,
QOpcUaAttributeOperand
and
QOpcUaSimpleAttributeOperand
and an operator into a content filter element. Only the last operator is used, previous operators will be discarded.
The following EventFilter tells the server to report the value of the "Message" field for events that have a "Severity" field with value >= 500:
QOpcUaMonitoringParameters::EventFilter filter; filter << QOpcUaSimpleAttributeOperand("Message"); // Select clause of the filter QOpcUaContentFilterElement condition; condition << QOpcUaContentFilterElement::FilterOperator::GreaterThanOrEqual; condition << QOpcUaSimpleAttributeOperand("Severity"); condition << QOpcUaLiteralOperand(500, QOpcUa::Types::UInt16); filter << condition; // Where clause of the filter
For a more complex example with two conditions, see QOpcUaElementOperand .
Constructs an event filter from rhs .
Returns the selected event fields that shall be included when a new event is reported.
另请参阅 setSelectClauses ().
Returns a reference to the select clauses.
Sets the select clauses to selectClauses .
另请参阅 selectClauses ().
Sets the where clause to whereClause .
另请参阅 whereClause ().
Returns the content filter used to restrict the reported events to events matching certain criteria.
另请参阅 setWhereClause ().
Returns a reference to the where clause.
另请参阅 whereClause ().
Converts this event filter to QVariant .
Adds the content filter element whereClauseElement to the where clause of this event filter.
Adds the simple attribute operand selectClauseElement to the select clause of this content filter element.
设置值从 rhs in this event filter.
返回
true
if this event filter has the same value as
rhs
.
