libpqxx
4.0.1
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#include <transaction_base.hxx>
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. | |
std::string | esc (const char str[]) const |
Escape string for use as SQL string literal in this transaction. | |
std::string | esc (const char str[], size_t maxlen) const |
Escape string for use as SQL string literal in this transaction. | |
std::string | esc (const std::string &str) const |
Escape string for use as SQL string literal in this transaction. | |
std::string | esc_raw (const unsigned char str[], size_t len) const |
Escape binary data for use as SQL string literal in this transaction. | |
std::string | esc_raw (const std::string &) const |
Escape binary data for use as SQL string literal in this transaction. | |
template<typename T > | |
std::string | quote (const T &t) const |
Represent object as SQL string, including quoting & escaping. | |
std::string | quote_raw (const unsigned char str[], size_t len) const |
Binary-escape and quote a binarystring for use as an SQL constant. | |
std::string | quote_raw (const std::string &str) const |
std::string | quote_name (const std::string &identifier) const |
Escape an SQL identifier for use in a query. | |
result | exec (const std::string &Query, const std::string &Desc=std::string()) |
Execute query. | |
result | exec (const std::stringstream &Query, const std::string &Desc=std::string()) |
internal::parameterized_invocation | parameterized (const std::string &query) |
Parameterize a statement. | |
connection_base & | conn () const |
Connection this transaction is running in. | |
void | set_variable (const std::string &Var, const std::string &Val) |
Set session variable in this connection. | |
std::string | get_variable (const std::string &) |
Get currently applicable value of variable. | |
Prepared statements | |
prepare::invocation | prepared (const std::string &statement=std::string()) |
Execute prepared statement. | |
Error/warning output | |
void | process_notice (const char Msg[]) const |
Have connection process warning message. | |
void | process_notice (const std::string &Msg) const |
Have connection process warning message. | |
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namedclass (const std::string &Classname, const std::string &Name="") | |
const std::string & | name () const throw () |
const std::string & | classname () const throw () |
std::string | description () const |
Protected Member Functions | |
transaction_base (connection_base &c, bool direct=true) | |
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. | |
void | reactivation_avoidance_clear () throw () |
Forget about any reactivation-blocking resources we tried to allocate. |
Protected Attributes | |
internal::reactivation_avoidance_counter | m_reactivation_avoidance |
Resources allocated in this transaction that make reactivation impossible. |
If nothing else is known, our isolation level is at least read_committed.
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pure virtual |
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explicitprotected |
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.
c | The connection that this transaction is to act on. |
direct | Running directly in connection context (i.e. not nested)? |
References conn(), and transaction_base().
Referenced by transaction_base().
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.
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protected |
Begin transaction (to be called by implementing class)
Will typically be called from implementing class' constructor.
Referenced by pqxx::transaction< ISOLATIONLEVEL, READWRITE >::transaction().
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.
Referenced by pqxx::largeobject::RawConnection(), pqxx::internal::sql_cursor::sql_cursor(), transaction_base(), and pqxx::transaction< ISOLATIONLEVEL, READWRITE >::~transaction().
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protected |
Execute query on connection directly.
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). |
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protectedpure virtual |
To be implemented by derived implementation class: abort transaction.
Implemented in pqxx::dbtransaction.
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protectedpure virtual |
To be implemented by derived implementation class: start transaction.
Implemented in pqxx::dbtransaction.
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protectedpure virtual |
To be implemented by derived implementation class: commit transaction.
Implemented in pqxx::dbtransaction.
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protectedpure virtual |
To be implemented by derived implementation class: perform query.
Implemented in pqxx::dbtransaction.
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protected |
End transaction. To be called by implementing class' destructor.
Referenced by pqxx::transaction< ISOLATIONLEVEL, READWRITE >::~transaction().
pqxx::result pqxx::transaction_base::exec | ( | const std::string & | Query, |
const std::string & | Desc = std::string() |
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Execute query.
Perform a query in this transaction.
This is one of the most important functions in libpqxx.
Most libpqxx exceptions can be thrown from here, including sql_error, broken_connection, and many sql_error subtypes such as feature_not_supported or insufficient_privilege. But any exception thrown by the C++ standard library may also occur here. All exceptions will be derived from std::exception, however, and all libpqxx-specific exception types are derived from pqxx::pqxx_exception.
Query | Query or command to execute |
Desc | Optional identifier for query, to help pinpoint SQL errors |
Referenced by pqxx::internal::sql_cursor::sql_cursor().
result pqxx::transaction_base::exec | ( | const std::stringstream & | Query, |
const std::string & | Desc = std::string() |
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string pqxx::transaction_base::get_variable | ( | const std::string & | Var | ) |
Get currently applicable value of variable.
First consults an internal cache of variables that have been set (whether in the ongoing transaction or in the connection) using the set_variable functions. If it is not found there, the database is queried.
const
but isn't anymore. pqxx::internal::parameterized_invocation pqxx::transaction_base::parameterized | ( | const std::string & | query | ) |
Parameterize a statement.
pqxx::prepare::invocation pqxx::transaction_base::prepared | ( | const std::string & | statement = std::string() | ) |
Execute prepared statement.
Prepared statements are defined using the connection classes' prepare() function, and continue to live on in the ongoing session regardless of the context they were defined in (unless explicitly dropped using the connection's unprepare() function). Their execution however, like other forms of query execution, requires a transaction object.
Just like param_declaration is a helper class that lets you tag parameter declarations onto the statement declaration, the invocation class returned here lets you tag parameter values onto the call:
Here, parameter 1 (written as "<tt>$1</tt>" in the statement's body) is a string that receives the value "param1"; the second parameter is an integer with the value 2; the third receives a null, making its type irrelevant; and number 4 again is an integer. The ultimate invocation of exec() is essential; if you forget this, nothing happens.
To see whether any prepared statement has been defined under a given name, use:
If you leave out the statement name, the call refers to the nameless statement instead.
void pqxx::transaction_base::process_notice | ( | const char | Msg[] | ) | const |
Have connection process warning message.
void pqxx::transaction_base::process_notice | ( | const std::string & | Msg | ) | const |
Have connection process warning message.
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protected |
Forget about any reactivation-blocking resources we tried to allocate.
References pqxx::result::clear().
void pqxx::transaction_base::set_variable | ( | const std::string & | Var, |
const std::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.
Var | The variable to set |
Val | The new value to store in the variable |
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Resources allocated in this transaction that make reactivation impossible.
This number may be negative!