pqxx::transaction_base Class Reference

Interface definition (and common code) for "transaction" classes. More...

#include <transaction_base.hxx>

Inheritance diagram for pqxx::transaction_base:

List of all members.

Public Types
typedef isolation_traits< read_committed >	isolation_tag
	If nothing else is known, our isolation level is at least read_committed.
Public Member Functions
virtual	~transaction_base ()=0
void	commit ()
	Commit the transaction.
void	abort ()
	Abort the transaction.
result	exec (const char Query[], const PGSTD::string &Desc=PGSTD::string())
	Execute query.
result	exec (const PGSTD::string &Query, const PGSTD::string &Desc=PGSTD::string())
	Execute query.
result	exec (const PGSTD::stringstream &Query, const PGSTD::string &Desc=PGSTD::string())
void	process_notice (const char Msg[]) const
	Have connection process warning message.
void	process_notice (const PGSTD::string &Msg) const
	Have connection process warning message.
connection_base &	conn () const
	Connection this transaction is running in.
void	set_variable (const PGSTD::string &Var, const PGSTD::string &Val)
	Set session variable in this connection.
PGSTD::string	get_variable (const PGSTD::string &) const
	Get currently applicable value of variable.
Protected Member Functions
	transaction_base (connection_base &, const PGSTD::string &TName, const PGSTD::string &CName)
	Create a transaction (to be called by implementation classes only).
void	Begin ()
	Begin transaction (to be called by implementing class).
void	End () throw ()
	End transaction. To be called by implementing class' destructor.
virtual void	do_begin ()=0
	To be implemented by derived implementation class: start transaction.
virtual result	do_exec (const char Query[])=0
	To be implemented by derived implementation class: perform query.
virtual void	do_commit ()=0
	To be implemented by derived implementation class: commit transaction.
virtual void	do_abort ()=0
	To be implemented by derived implementation class: abort transaction.
result	DirectExec (const char C[], int Retries=0)
	Execute query on connection directly.
Friends
class	Cursor
class	cursor_base
class	internal::transactionfocus
class	tablereader
class	tablewriter
class	pipeline

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Detailed Description

Interface definition (and common code) for "transaction" classes.

All database access must be channeled through one of these classes for safety, although not all implementations of this interface need to provide full transactional integrity.

Several implementations of this interface are shipped with libpqxx, including the plain transaction class, the entirely unprotected nontransaction, and the more cautions robusttransaction.

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Member Typedef Documentation

typedef isolation_traits<read_committed> pqxx::transaction_base::isolation_tag

If nothing else is known, our isolation level is at least read_committed. Reimplemented in pqxx::basic_robusttransaction, pqxx::robusttransaction< ISOLATIONLEVEL >, and pqxx::transaction< ISOLATIONLEVEL >.

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Constructor & Destructor Documentation

pqxx::transaction_base::~transaction_base (   )  [pure virtual]

pqxx::transaction_base::transaction_base (  connection_base &  , const PGSTD::string &  TName, const PGSTD::string &  CName )  [explicit, protected]

Create a transaction (to be called by implementation classes only). The optional name, if nonempty, must begin with a letter and may contain letters and digits only.

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Member Function Documentation

void pqxx::transaction_base::abort (   )

Abort the transaction. No special effort is required to call this function; it will be called implicitly when the transaction is destructed.

void pqxx::transaction_base::Begin (   )  [protected]

Begin transaction (to be called by implementing class). Will typically be called from implementing class' constructor.

void pqxx::transaction_base::commit (   )

Commit the transaction. Unless this function is called explicitly, the transaction will not be committed (actually the nontransaction implementation breaks this rule, hence the name). Once this function returns, the whole transaction will typically be irrevocably completed in the database. There is also, however, a minute risk that the connection to the database may be lost at just the wrong moment. In that case, libpqxx may be unable to determine whether the transaction was completed or aborted and an in_doubt_error will be thrown to make this fact known to the caller. The robusttransaction implementation takes some special precautions to reduce this risk.

connection_base& pqxx::transaction_base::conn (   )  const

Connection this transaction is running in.

pqxx::result pqxx::transaction_base::DirectExec (  const char  C[], int  Retries = 0 )  [protected]

Execute query on connection directly. Parameters: C  Query or command to execute Retries  Number of times to retry the query if it fails. Be extremely careful with this option; if you retry in the middle of a transaction, you may be setting up a new connection transparently and executing the latter part of the transaction without a backend transaction being active (and with the former part aborted).

virtual void pqxx::transaction_base::do_abort (   )  [protected, pure virtual]

To be implemented by derived implementation class: abort transaction.

virtual void pqxx::transaction_base::do_begin (   )  [protected, pure virtual]

To be implemented by derived implementation class: start transaction.

virtual void pqxx::transaction_base::do_commit (   )  [protected, pure virtual]

To be implemented by derived implementation class: commit transaction.

virtual result pqxx::transaction_base::do_exec (  const char  Query[]  )  [protected, pure virtual]

To be implemented by derived implementation class: perform query.

void pqxx::transaction_base::End (   )  throw () [protected]

End transaction. To be called by implementing class' destructor.

result pqxx::transaction_base::exec (  const PGSTD::stringstream &  Query, const PGSTD::string &  Desc = PGSTD::string() )

result pqxx::transaction_base::exec (  const PGSTD::string &  Query, const PGSTD::string &  Desc = PGSTD::string() )

Execute query. Perform a query in this transaction. This version may be slightly slower than the version taking a const char[], although the difference is not likely to be very noticeable compared to the time required to execute even a simple query. Parameters: Query  Query or command to execute Desc  Optional identifier for query, to help pinpoint SQL errors Returns: A result set describing the query's or command's result

pqxx::result pqxx::transaction_base::exec (  const char  Query[], const PGSTD::string &  Desc = PGSTD::string() )

Execute query. Perform a query in this transaction. Parameters: Query  Query or command to execute Desc  Optional identifier for query, to help pinpoint SQL errors Returns: A result set describing the query's or command's result

string pqxx::transaction_base::get_variable (  const PGSTD::string &   )  const

Get currently applicable value of variable. This function will try to consult the cache of variables set (both in the transaction and in the connection) using the set_variable functions. If it is not found there, the database is queried. Warning: Do not mix the set_variable with raw "SET" queries, and do not try to set or get variables while a pipeline or table stream is active.

void pqxx::transaction_base::process_notice (  const PGSTD::string &  Msg  )  const

Have connection process warning message.

void pqxx::transaction_base::process_notice (  const char  Msg[]  )  const

Have connection process warning message.

void pqxx::transaction_base::set_variable (  const PGSTD::string &  Var, const PGSTD::string &  Val )

Set session variable in this connection. The new value is typically forgotten if the transaction aborts. Known exceptions to this rule are nontransaction, and PostgreSQL versions prior to 7.3. In the case of nontransaction, the set value will be kept regardless; but in that case, if the connection ever needs to be recovered, the set value will not be restored. Parameters: Var  The variable to set Val  The new value to store in the variable

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Friends And Related Function Documentation

friend class Cursor [friend]

friend class cursor_base [friend]

friend class internal::transactionfocus [friend]

friend class pipeline [friend]

friend class tablereader [friend]

friend class tablewriter [friend]

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

• transaction_base.hxx
• transaction_base.cxx

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