Reads a server's data types and decodes/encodes generic structs from/to extension objects. 更多...
头: | #include <QOpcUaGenericStructHandler> |
CMake: |
find_package(Qt6 REQUIRED COMPONENTS OpcUa)
target_link_libraries(mytarget PRIVATE Qt6::OpcUa) |
qmake: | QT += opcua |
Since: | Qt 6.7 |
继承: | QObject |
enum class | DataTypeKind { Unknown, Struct, Enum, Other } |
QOpcUaGenericStructHandler (QOpcUaClient * client , QObject * parent = nullptr) | |
bool | addCustomEnumDefinition (const QOpcUaEnumDefinition & definition , const QString & typeId , const QString & name , QOpcUa::IsAbstract isAbstract = QOpcUa::IsAbstract::NotAbstract) |
bool | addCustomStructureDefinition (const QOpcUaStructureDefinition & definition , const QString & typeId , const QString & name , QOpcUa::IsAbstract isAbstract = QOpcUa::IsAbstract::NotAbstract) |
QOpcUaGenericStructValue | createGenericStructValueForTypeId (const QString & typeId ) |
QOpcUaGenericStructHandler::DataTypeKind | dataTypeKindForTypeId (const QString & id ) const |
std::optional<QOpcUaGenericStructValue> | decode (const QOpcUaExtensionObject & extensionObject ) const |
std::optional<QOpcUaExtensionObject> | encode (const QOpcUaGenericStructValue & value ) |
QOpcUaEnumDefinition | enumDefinitionForTypeId (const QString & id ) const |
bool | initialize () |
(从 6.7 起)
bool
|
initialized () const |
bool | isAbstractTypeId (const QString & id ) const |
QOpcUaStructureDefinition | structureDefinitionForBinaryEncodingId (const QString & id ) const |
QOpcUaStructureDefinition | structureDefinitionForTypeId (const QString & id ) const |
QString | typeIdForBinaryEncodingId (const QString & id ) const |
QString | typeNameForBinaryEncodingId (const QString & id ) const |
QString | typeNameForTypeId (const QString & id ) const |
void | initializedChanged (bool initialized ) |
The binary data encoding used in OPC UA was designed with a small message size in mind and doesn't contain any information about the structure of the data. This means that a decoder must known the structure of the encoded data in advance to be able to decode a data buffer.
Since OPC UA 1.04, nodes of the DataType node class may have the DataTypeDefinition attribute which contain information about the fields of structured types and the mapping of enum values to names. Together with the knowledge about how to decode built-in types, this allows a client to decode generic custom structured types without relying on outside knowledge.
QOpcUaGenericStructHandler traverses the type hierarchy of a server by following the HasSubtype references starting from BaseDataType and reads the DataTypeDefinition attribute of the nodes.
For structured types where a QOpcUaStructureDefinition value is present in the DataTypeDefinition attribute, automatic decoding of extension objects containing them is available. Fields with a built-in type or a type where a C++ data class exists are deserialized to the corresponding Qt OPC UA type, other generic structs are serialized to a nested QOpcUaGenericStructValue . All nested generic struct values must have a QOpcUaStructureDefinition in the server or decoding fails.
The same conditions apply to encoding a custom struct.
Example for decoding a custom struct:
QOpcUaGenericStructHandler handler(opcuaClient); handler.initialize(); QObject::connect(&handler, &QOpcUaGenericStructHandler::initializedChanged, [opcuaClient, &handler](bool initialized) { if (!initialized) return; auto node = opcuaClient->node("ns=4;i=3003"); // A custom struct test node in the open62541-testserver node->readValueAttribute(); QObject::connect(node, &QOpcUaNode::attributeRead, [node, &handler](QOpcUa::NodeAttributes attr) { if (!attr.testFlag(QOpcUa::NodeAttribute::Value) || node->valueAttributeError() != QOpcUa::UaStatusCode::Good) return; auto extObj = node->valueAttribute().value<QOpcUaExtensionObject>(); qDebug() << "Got object of type" << handler.typeNameForBinaryEncodingId(extObj.encodingTypeId()); const auto result = handler.decode(extObj); if (!result) return; qDebug() << *result; }); });
Example for encoding a custom struct:
QOpcUaGenericStructHandler handler(opcuaClient); handler.initialize(); QObject::connect(&handler, &QOpcUaGenericStructHandler::initializedChanged, [opcuaClient, &handler](bool initialized) { if (!initialized) return; QOpcUaGenericStructValue value = handler.createGenericStructValueForTypeId("ns=4;i=3006"); value.fieldsRef()["MandatoryMember"] = 23.0; value.fieldsRef()["OptionalMember"] = 42.0; const auto ext = handler.encode(value); if (!ext) return; // Use the extension object to write a node's value attribute, in a method parameter, etc... });
This enum type specifies data type kind of a data type node.
常量 | 值 | 描述 |
---|---|---|
QOpcUaGenericStructHandler::DataTypeKind::Unknown
|
0
|
The type node id is unknown. |
QOpcUaGenericStructHandler::DataTypeKind::Struct
|
1
|
The type node id belongs to a structured type. |
QOpcUaGenericStructHandler::DataTypeKind::Enum
|
2
|
The type node id belongs to an enum type. |
QOpcUaGenericStructHandler::DataTypeKind::Other
|
3
|
The type node id belongs to a type which is not a struct or enum (other built-in types or their subtypes) |
[explicit]
QOpcUaGenericStructHandler::
QOpcUaGenericStructHandler
(
QOpcUaClient
*
client
,
QObject
*
parent
= nullptr)
Constructs a generic struct handler for client .
Adds the custom enum definition definition to the known types. This can be used to support custom structures the server doesn't expose a StructureDefinition for. The parameters definition , typeId and name are required for proper decoding and encoding. If isAbstract is set, the type can't be encoded and decoded.
返回
true
if the enum definition was successfully added.
Adds the custom structure definition definition to the known types. This can be used to support custom structures the server doesn't expose a StructureDefinition for. The parameters definition , typeId and name are required for proper decoding and encoding. If isAbstract is set, the type can't be encoded and decoded.
返回
true
if the structure definition was successfully added.
Returns a generic struct value pre-filled with the struct definition, type id and type name corresponding to typeId . For all mandatory fields, an invalid placeholder QVariant will be inserted.
Returns the data type kind for the type node id id .
Decodes
extensionObject
到
QOpcUaGenericStructValue
. If the decoder fails,
std::nullopt
被返回。
返回
value
encoded as a
QOpcUaExtensionObject
,或
std::nullopt
if the value could not be encoded.
返回 QOpcUaEnumDefinition for the type node id id . If the node id is unknown or does not belong to an enum type, a default constructed value is returned.
Starts the data type hierarchy traversal. Success or failure is reported in the initializedChanged 信号。
返回
false
if the operation can't be started.
[since 6.7]
bool
QOpcUaGenericStructHandler::
initialized
() const
返回
true
if the generic struct handler is initialized.
该函数在 Qt 6.7 引入。
[signal]
void
QOpcUaGenericStructHandler::
initializedChanged
(
bool
initialized
)
This signal is emitted when the initialization process has finished. initialized indicates if the initialization was successful.
Returns true if the data type described by id is abstract.
返回 QOpcUaStructureDefinition for the binary encoding node id id . If the node id is unknown or does not belong to a struct type, a default constructed value is returned.
返回 QOpcUaStructureDefinition for the type node id id . If the node id is unknown or does not belong to a struct type, a default constructed value is returned.
Returns the type node id associated with the binary encoding id id .
Returns the type name belonging to the binary encoding node id id . If the node id is unknown or does not belong to a struct type, an empty string is returned.
Returns the type name belonging to a data type node identified by type node id id . If the node id is unknown, an empty string is returned.