The GetSingleValue class is intended for get a single value from database. The value is selected by primaryKey. By Default the primary key is 'id'. More...

#include <getsinglevalue.h>

Inheritance diagram for QH::PKG::GetSingleValue:

Collaboration diagram for QH::PKG::GetSingleValue:

Public Member Functions
	GetSingleValue (const DbAddress &address, const QString &field, const QString &primaryKey="id")
	GetSingleValue This is default constructor of the GetMaxIntegerId class.

QVariant	value () const
	value This method return Maximum value of a sql tables field.

DBObject *	createDBObject () const override
	createDBObject This method should be create a object with the some type as the object called this method. Example of override:

PrepareResult	prepareSelectQuery (QSqlQuery &q) const override
	prepareSelectQuery This method should be prepare a query for selected data. Override this method for get item from database. The default implementation generate default select:

bool	fromSqlRecord (const QSqlRecord &q) override
	fromSqlRecord This method should be initialize this object from the executed sqlRecord. The Default implementation get general dbObject information ( id and table name ). Override This method for initialize this object from sql query.

bool	isCached () const override
	isCached This method sholud be return status of object. If this method return true then this object can be saved into cache of database. Override this method and set this value to false for composite objects (objects for which a select query can return several objects or an object that does not have a direct representation in the database but contains common characteristics of several objects).

QString	table () const override
	table This method should be return name of the database table that should be contains objects with this type.

Public Member Functions inherited from QH::PKG::DBObject
	DBObject ()

	~DBObject () override

bool	isValid () const override
	isValid This method check current object to valid.

bool	isHaveAPrimaryKey () const
	isHaveAPrimaryKey This method return true if this object has a primary key. If you want to cache this database object then primary key must be not null.

virtual void	clear ()
	clear This method clear all data of database object. Override This method for remove or reset your own members of class.

virtual PrepareResult	prepareInsertQuery (QSqlQuery &q, bool replace) const
	prepareInsertQuery This method should be prepare a query for insert object into database. You need to create a own insert sql query for this object into database. Override this method for insert item into database. By Default This method prepare a insert query using the data that returned from the variantMap method.

virtual PrepareResult	prepareUpdateQuery (QSqlQuery &q) const
	prepareUpdateQuery this method should be prepare a insert data query.

virtual PrepareResult	prepareRemoveQuery (QSqlQuery &q) const
	prepareRemoveQuery This method should be prepare a query for remove this object from a database. Override this method for remove this item from database. The default implementation remove item from id or primaryKey for more information see DBObject::condition method.

virtual bool	isBundle () const
	isBundle This method definef determines whether the object will be abstract (composite objects) or single object If this function return true then SqlDBWriter create only one object after invoked selectquery. And if the selectquery function return a list of more 1 elements then a method fromSqlRecord must be invoked for each all elements of list.

DbAddress	dbAddress () const
	dbAddress This method return address of the database object. IF the object is not valid then this method return an invalid database address.

QString	toString () const override

virtual DBVariantMap	variantMap () const
	variantMap This method should be create a DBVariantMap implementation of this database object.

Public Member Functions inherited from QH::PKG::AbstractData
	~AbstractData () override

virtual unsigned short	cmd () const =0
	cmd - This is command of this object, (for generate cmd use macross QH_PACKAGE)

virtual QString	cmdString () const =0
	cmdString - This is command string of this object, (for generate cmd use macross QH_PACKAGE)

virtual bool	toPackage (Package &package, const DistVersion &reqVersion, unsigned int triggerHash=0) const
	toPackage This method convert this class object to the package. For more info see Package class.

QString	toString () const override
	toString - Return a string implementation for this object.

template<class C , class... Args>
C *	create (Args &&... args) const
	create - This is factory method for create a new object.

void	fromPakcage (const Package &pkg)
	fromPakcage - This method initialize the current object from a package class object.

Public Member Functions inherited from QH::StreamBase
	StreamBase ()

virtual	~StreamBase ()

bool	fromBytes (const QByteArray &data)
	fromBytes This method provide initialization of object from byte array.

QByteArray	toBytes () const
	toBytes This method convert a current object to bytes array.

bool	fromBase64 (const QString &data)
	fromBase64 This method provide initialization of object from the base64 string.

bool	fromBase64 (const QByteArray &data)
	fromBase64 This method provide initialization of object from the base64 string.

QByteArray	toBase64 () const
	toBase64 This method convert a current object to the base64 string.

template<class T >
T &	copy (const StreamBase &right)
	copy This is base copy method for all StreamBase structures. Default implementation it is copy from byteArray.

template<class T >
bool	compare (const T &right)
	compare This method compare array signatures of this and right objects.

Protected Member Functions
QString	primaryKey () const override
	primaryKey This method must be return the name of primary key of this object table. If you want to create data object without primary key just return empty string.

QVariant	primaryValue () const override
	primaryValue This method is wraper of DBAddress::id. If This object do not contains a id value then return invalid value.

Protected Member Functions inherited from QH::PKG::DBObject
QDataStream &	fromStream (QDataStream &stream) override
	fromStream This method should be read all bytes from the stream object and full the current object.

QDataStream &	toStream (QDataStream &stream) const override
	fromStream This method should be write all members of the current object to the stream object.

virtual std::pair< QString, QMap< QString, QVariant > >	condition () const
	condition This method must to return a condition of the WHERE block of the sql query. This method using on default implementation of DBObject::prepareSelectQuery and DBObject::prepareRemoveQuery methods. The default implementation generate when block by map for more information see the variantMap nethod. Override this method for customize your select or delete query.

bool	isInsertPrimaryKey () const
	isInsertPrimaryKey This method check primaryKeys type. If the primary key have a type MemberType::Insert then return true.

Protected Member Functions inherited from QH::PKG::AbstractData
	AbstractData ()
	AbstractData - Base constructor of this object.

Protected Member Functions inherited from QH::StreamBase
virtual int	parsingVersion () const
	parsingVersion this method return parsing version of Qt. By Default is 0 (last available parsing). see https://doc.qt.io/qt-6/qdatastream.html#Version-enum

virtual unsigned int	typeId () const
	typeId This method return id of type.

Additional Inherited Members
Static Public Member Functions inherited from QH::PKG::AbstractData
static unsigned int	command ()
	command This static method that return glaball code of this object.

static QString	commandText ()
	commandText This method return text of package command

Detailed Description

The GetSingleValue class is intended for get a single value from database. The value is selected by primaryKey. By Default the primary key is 'id'.

Example of use

QH::PKG::GetSingleValue request({"TableName", "PrimarykeyValue"}, "requestFieldColumName", "PrimaryKey");
auto result = _db->getObject(request);
 
if (!result) {
    return 0;
}
 
auto resultValue = result->value();

See also: SetSingleValue

Definition at line 39 of file getsinglevalue.h.

Constructor & Destructor Documentation

◆ GetSingleValue()

QH::PKG::GetSingleValue::GetSingleValue	(	const DbAddress &	address,
		const QString &	field,
		const QString &	primaryKey = `"id"`
	)

GetSingleValue This is default constructor of the GetMaxIntegerId class.

Parameters

address	This is address of getting object.
field	This is name of field.
primaryKey	This is primary key that will be using in selected query.

Definition at line 17 of file getsinglevalue.cpp.

Here is the call graph for this function:

Member Function Documentation

◆ createDBObject()

DBObject * QH::PKG::GetSingleValue::createDBObject ( ) const

overridevirtual

createDBObject This method should be create a object with the some type as the object called this method. Example of override:

return create<MyClassName>();

Note: The object created on this method not destroyed automatically.

Returns: pointer of new object with the same type.

Implements QH::PKG::DBObject.

Definition at line 31 of file getsinglevalue.cpp.

Here is the call graph for this function:

◆ fromSqlRecord()

bool QH::PKG::GetSingleValue::fromSqlRecord ( const QSqlRecord & q )

overridevirtual

fromSqlRecord This method should be initialize this object from the executed sqlRecord. The Default implementation get general dbObject information ( id and table name ). Override This method for initialize this object from sql query.

Note: This method will be invoke for one object. But if isBundle return 'true' then a function fromSqlRecord moust be invoked for each all elements of list.

Parameters

q	This is query object.

Returns: true if method finished successful.

Exampel of override fromSqlRecord method:

bool ExampleObject::fromSqlRecord(const QSqlRecord &q) {
 
    id = q.value("id").toInt();
    exampleMember = q.value("exampleMember").toInt();
    return isValid();
}

Implements QH::PKG::DBObject.

Definition at line 48 of file getsinglevalue.cpp.

◆ isCached()

bool QH::PKG::GetSingleValue::isCached ( ) const

overridevirtual

isCached This method sholud be return status of object. If this method return true then this object can be saved into cache of database. Override this method and set this value to false for composite objects (objects for which a select query can return several objects or an object that does not have a direct representation in the database but contains common characteristics of several objects).

Returns: True if item in cache. The Default implementation check the primary key if this object and if primary key is valid then return true else return false.

Reimplemented from QH::PKG::DBObject.

Definition at line 54 of file getsinglevalue.cpp.

◆ prepareSelectQuery()

PrepareResult QH::PKG::GetSingleValue::prepareSelectQuery ( QSqlQuery & q ) const

overridevirtual

prepareSelectQuery This method should be prepare a query for selected data. Override this method for get item from database. The default implementation generate default select:

"select * from [table] where id=[id]".

This method create where block using the condition method. See DBObject::condition fr more information.

Parameters

q	This is query object.

Returns: PrepareResult object with information about prepare results.

Note: If you want disable this mehod just override it and return the PrepareResult::Disabled value.

Reimplemented from QH::PKG::DBObject.

Definition at line 35 of file getsinglevalue.cpp.

Here is the call graph for this function:

◆ primaryKey()

QString QH::PKG::GetSingleValue::primaryKey ( ) const

overrideprotectedvirtual

primaryKey This method must be return the name of primary key of this object table. If you want to create data object without primary key just return empty string.

Note: If you returned empty value then this method can not be prepare insert update and delete querys.

Returns: The primary key name.

Reimplemented from QH::PKG::DBObject.

Definition at line 62 of file getsinglevalue.cpp.

Here is the caller graph for this function:

◆ primaryValue()

QVariant QH::PKG::GetSingleValue::primaryValue ( ) const

overrideprotectedvirtual

primaryValue This method is wraper of DBAddress::id. If This object do not contains a id value then return invalid value.

Returns: Value of primaryKey ( database id ).

Note: If you alredy override the condition method then You can return empty string because this method using in generate default condition only.

See also: DBObject::condition.

Reimplemented from QH::PKG::DBObject.

Definition at line 66 of file getsinglevalue.cpp.

◆ table()

QString QH::PKG::GetSingleValue::table ( ) const

overridevirtual

table This method should be return name of the database table that should be contains objects with this type.

Returns: table name that contains object with this type.

Implements QH::PKG::DBObject.

Definition at line 58 of file getsinglevalue.cpp.

Here is the caller graph for this function:

◆ value()

QVariant QH::PKG::GetSingleValue::value ( ) const

value This method return Maximum value of a sql tables field.

Returns: Maximum value of a sql tables field.

Definition at line 27 of file getsinglevalue.cpp.

Here is the caller graph for this function:

The documentation for this class was generated from the following files:

src/public/packages/getsinglevalue.h
src/public/packages/getsinglevalue.cpp

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ GetSingleValue()

Member Function Documentation

◆ createDBObject()

◆ fromSqlRecord()

◆ isCached()

◆ prepareSelectQuery()

◆ primaryKey()

◆ primaryValue()

◆ table()

◆ value()