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statement.cpp
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statement.cpp
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//
// Copyright (C) 2004-2008 Maciej Sobczak, Stephen Hutton
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
#define SOCI_POSTGRESQL_SOURCE
#include "soci-postgresql.h"
#include "error.h"
#include <soci-platform.h>
#include <libpq/libpq-fs.h> // libpq
#include <cctype>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <sstream>
#ifdef SOCI_POSTGRESQL_NOPARAMS
#define SOCI_POSTGRESQL_NOBINDBYNAME
#endif // SOCI_POSTGRESQL_NOPARAMS
#ifdef _MSC_VER
#pragma warning(disable:4355)
#endif
using namespace soci;
using namespace soci::details;
using namespace soci::details::postgresql;
postgresql_statement_backend::postgresql_statement_backend(
postgresql_session_backend &session)
: session_(session), result_(NULL), justDescribed_(false),
hasIntoElements_(false), hasVectorIntoElements_(false),
hasUseElements_(false), hasVectorUseElements_(false)
{
}
postgresql_statement_backend::~postgresql_statement_backend()
{
if (statementName_.empty() == false)
session_.deallocate_prepared_statement(statementName_);
}
void postgresql_statement_backend::alloc()
{
// nothing to do here
}
void postgresql_statement_backend::clean_up()
{
if (result_ != NULL)
{
PQclear(result_);
result_ = NULL;
}
}
void postgresql_statement_backend::prepare(std::string const & query,
statement_type stType)
{
#ifdef SOCI_POSTGRESQL_NOBINDBYNAME
query_ = query;
#else
// rewrite the query by transforming all named parameters into
// the postgresql_ numbers ones (:abc -> $1, etc.)
enum { normal, in_quotes, in_name } state = normal;
std::string name;
int position = 1;
for (std::string::const_iterator it = query.begin(), end = query.end();
it != end; ++it)
{
switch (state)
{
case normal:
if (*it == '\'')
{
query_ += *it;
state = in_quotes;
}
else if (*it == ':')
{
// Check whether this is a cast operator (e.g. 23::float)
// and treat it as a special case, not as a named binding
const std::string::const_iterator next_it = it + 1;
if ((next_it != end) && (*next_it == ':'))
{
query_ += "::";
++it;
}
else
{
state = in_name;
}
}
else // regular character, stay in the same state
{
query_ += *it;
}
break;
case in_quotes:
if (*it == '\'')
{
query_ += *it;
state = normal;
}
else // regular quoted character
{
query_ += *it;
}
break;
case in_name:
if (std::isalnum(*it) || *it == '_')
{
name += *it;
}
else // end of name
{
names_.push_back(name);
name.clear();
std::ostringstream ss;
ss << '$' << position++;
query_ += ss.str();
query_ += *it;
state = normal;
// Check whether the named parameter is immediatelly
// followed by a cast operator (e.g. :name::float)
// and handle the additional colon immediately to avoid
// its misinterpretation later on.
if (*it == ':')
{
const std::string::const_iterator next_it = it + 1;
if ((next_it != end) && (*next_it == ':'))
{
query_ += ':';
++it;
}
}
}
break;
}
}
if (state == in_name)
{
names_.push_back(name);
std::ostringstream ss;
ss << '$' << position++;
query_ += ss.str();
}
#endif // SOCI_POSTGRESQL_NOBINDBYNAME
#ifndef SOCI_POSTGRESQL_NOPREPARE
if (stType == st_repeatable_query)
{
statementName_ = session_.get_next_statement_name();
PGresult * res = PQprepare(session_.conn_, statementName_.c_str(),
query_.c_str(), static_cast<int>(names_.size()), NULL);
if (res == NULL)
{
throw soci_error("Cannot prepare statement.");
}
ExecStatusType status = PQresultStatus(res);
if (status != PGRES_COMMAND_OK)
{
throw_postgresql_soci_error(res);
}
PQclear(res);
}
stType_ = stType;
#endif // SOCI_POSTGRESQL_NOPREPARE
}
statement_backend::exec_fetch_result
postgresql_statement_backend::execute(int number)
{
// If the statement was "just described", then we know that
// it was actually executed with all the use elements
// already bound and pre-used. This means that the result of the
// query is already on the client side, so there is no need
// to re-execute it.
if (justDescribed_ == false)
{
// This object could have been already filled with data before.
clean_up();
if (number > 1 && hasIntoElements_)
{
throw soci_error(
"Bulk use with single into elements is not supported.");
}
// Since the bulk operations are not natively supported by postgresql_,
// we have to explicitly loop to achieve the bulk operations.
// On the other hand, looping is not needed if there are single
// use elements, even if there is a bulk fetch.
// We know that single use and bulk use elements in the same query are
// not supported anyway, so in the effect the 'number' parameter here
// specifies the size of vectors (into/use), but 'numberOfExecutions'
// specifies the number of loops that need to be performed.
int numberOfExecutions = 1;
if (number > 0)
{
numberOfExecutions = hasUseElements_ ? 1 : number;
}
if ((useByPosBuffers_.empty() == false) ||
(useByNameBuffers_.empty() == false))
{
if ((useByPosBuffers_.empty() == false) &&
(useByNameBuffers_.empty() == false))
{
throw soci_error(
"Binding for use elements must be either by position "
"or by name.");
}
for (int i = 0; i != numberOfExecutions; ++i)
{
std::vector<char *> paramValues;
if (useByPosBuffers_.empty() == false)
{
// use elements bind by position
// the map of use buffers can be traversed
// in its natural order
for (UseByPosBuffersMap::iterator
it = useByPosBuffers_.begin(),
end = useByPosBuffers_.end();
it != end; ++it)
{
char ** buffers = it->second;
paramValues.push_back(buffers[i]);
}
}
else
{
// use elements bind by name
for (std::vector<std::string>::iterator
it = names_.begin(), end = names_.end();
it != end; ++it)
{
UseByNameBuffersMap::iterator b
= useByNameBuffers_.find(*it);
if (b == useByNameBuffers_.end())
{
std::string msg(
"Missing use element for bind by name (");
msg += *it;
msg += ").";
throw soci_error(msg);
}
char ** buffers = b->second;
paramValues.push_back(buffers[i]);
}
}
#ifdef SOCI_POSTGRESQL_NOPARAMS
throw soci_error("Queries with parameters are not supported.");
#else
#ifdef SOCI_POSTGRESQL_NOPREPARE
result_ = PQexecParams(session_.conn_, query_.c_str(),
static_cast<int>(paramValues.size()),
NULL, ¶mValues[0], NULL, NULL, 0);
#else
if (stType_ == st_repeatable_query)
{
// this query was separately prepared
result_ = PQexecPrepared(session_.conn_,
statementName_.c_str(),
static_cast<int>(paramValues.size()),
¶mValues[0], NULL, NULL, 0);
}
else // stType_ == st_one_time_query
{
// this query was not separately prepared and should
// be executed as a one-time query
result_ = PQexecParams(session_.conn_, query_.c_str(),
static_cast<int>(paramValues.size()),
NULL, ¶mValues[0], NULL, NULL, 0);
}
#endif // SOCI_POSTGRESQL_NOPREPARE
#endif // SOCI_POSTGRESQL_NOPARAMS
if (result_ == NULL)
{
throw soci_error("Cannot execute query.");
}
if (numberOfExecutions > 1)
{
// there are only bulk use elements (no intos)
ExecStatusType status = PQresultStatus(result_);
if (status != PGRES_COMMAND_OK)
{
throw_postgresql_soci_error(result_);
}
PQclear(result_);
}
}
if (numberOfExecutions > 1)
{
// it was a bulk operation
result_ = NULL;
return ef_no_data;
}
// otherwise (no bulk), follow the code below
}
else
{
// there are no use elements
// - execute the query without parameter information
#ifdef SOCI_POSTGRESQL_NOPREPARE
result_ = PQexec(session_.conn_, query_.c_str());
#else
if (stType_ == st_repeatable_query)
{
// this query was separately prepared
result_ = PQexecPrepared(session_.conn_,
statementName_.c_str(), 0, NULL, NULL, NULL, 0);
}
else // stType_ == st_one_time_query
{
result_ = PQexec(session_.conn_, query_.c_str());
}
#endif // SOCI_POSTGRESQL_NOPREPARE
if (result_ == NULL)
{
throw soci_error("Cannot execute query.");
}
}
}
else
{
// The optimization based on the existing results
// from the row description can be performed only once.
// If the same statement is re-executed,
// it will be *really* re-executed, without reusing existing data.
justDescribed_ = false;
}
ExecStatusType status = PQresultStatus(result_);
if (status == PGRES_TUPLES_OK)
{
currentRow_ = 0;
rowsToConsume_ = 0;
numberOfRows_ = PQntuples(result_);
if (numberOfRows_ == 0)
{
return ef_no_data;
}
else
{
if (number > 0)
{
// prepare for the subsequent data consumption
return fetch(number);
}
else
{
// execute(0) was meant to only perform the query
return ef_success;
}
}
}
else if (status == PGRES_COMMAND_OK)
{
return ef_no_data;
}
else
{
throw_postgresql_soci_error(result_);
// dummy, never reach
return ef_no_data;
}
}
statement_backend::exec_fetch_result
postgresql_statement_backend::fetch(int number)
{
// Note: This function does not actually fetch anything from anywhere
// - the data was already retrieved from the server in the execute()
// function, and the actual consumption of this data will take place
// in the postFetch functions, called for each into element.
// Here, we only prepare for this to happen (to emulate "the Oracle way").
// forward the "cursor" from the last fetch
currentRow_ += rowsToConsume_;
if (currentRow_ >= numberOfRows_)
{
// all rows were already consumed
return ef_no_data;
}
else
{
if (currentRow_ + number > numberOfRows_)
{
rowsToConsume_ = numberOfRows_ - currentRow_;
// this simulates the behaviour of Oracle
// - when EOF is hit, we return ef_no_data even when there are
// actually some rows fetched
return ef_no_data;
}
else
{
rowsToConsume_ = number;
return ef_success;
}
}
}
long long postgresql_statement_backend::get_affected_rows()
{
const char * resultStr = PQcmdTuples(result_);
char * end;
long long result = strtoll(resultStr, &end, 0);
if (end != resultStr)
{
return result;
}
else
{
return -1;
}
}
int postgresql_statement_backend::get_number_of_rows()
{
return numberOfRows_ - currentRow_;
}
std::string postgresql_statement_backend::rewrite_for_procedure_call(
std::string const & query)
{
std::string newQuery("select ");
newQuery += query;
return newQuery;
}
int postgresql_statement_backend::prepare_for_describe()
{
execute(1);
justDescribed_ = true;
int columns = PQnfields(result_);
return columns;
}
void postgresql_statement_backend::describe_column(int colNum, data_type & type,
std::string & columnName)
{
// In postgresql_ column numbers start from 0
int const pos = colNum - 1;
unsigned long const typeOid = PQftype(result_, pos);
switch (typeOid)
{
// Note: the following list of OIDs was taken from the pg_type table
// we do not claim that this list is exchaustive or even correct.
// from pg_type:
case 25: // text
case 1043: // varchar
case 2275: // cstring
case 18: // char
case 1042: // bpchar
case 142: // xml
type = dt_string;
break;
case 702: // abstime
case 703: // reltime
case 1082: // date
case 1083: // time
case 1114: // timestamp
case 1184: // timestamptz
case 1266: // timetz
type = dt_date;
break;
case 700: // float4
case 701: // float8
case 1700: // numeric
type = dt_double;
break;
case 16: // bool
case 21: // int2
case 23: // int4
case 26: // oid
type = dt_integer;
break;
case 20: // int8
type = dt_long_long;
break;
default:
{
std::stringstream message;
message << "unknown data type with typelem: " << typeOid << " for colNum: " << colNum << " with name: " << PQfname(result_, pos);
throw soci_error(message.str());
}
}
columnName = PQfname(result_, pos);
}
postgresql_standard_into_type_backend *
postgresql_statement_backend::make_into_type_backend()
{
hasIntoElements_ = true;
return new postgresql_standard_into_type_backend(*this);
}
postgresql_standard_use_type_backend *
postgresql_statement_backend::make_use_type_backend()
{
hasUseElements_ = true;
return new postgresql_standard_use_type_backend(*this);
}
postgresql_vector_into_type_backend *
postgresql_statement_backend::make_vector_into_type_backend()
{
hasVectorIntoElements_ = true;
return new postgresql_vector_into_type_backend(*this);
}
postgresql_vector_use_type_backend *
postgresql_statement_backend::make_vector_use_type_backend()
{
hasVectorUseElements_ = true;
return new postgresql_vector_use_type_backend(*this);
}