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sqlite plugin: unless <table> param is a subquery use PRAGMA table_info to query column names and types, and if SQLITE_NULL is encountered when inspecting actual query values fallback to empty strings since mapnik does not have a NULL type

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This commit is contained in:
Dane Springmeyer 2011-04-01 01:22:19 +00:00
parent 73e8dd06a0
commit 690ee25c36
2 changed files with 86 additions and 39 deletions
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117
plugins/input/sqlite/sqlite_datasource.cpp
View file

@ -2,7 +2,7 @@
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2007 Artem Pavlenko
* Copyright (C) 2010 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -166,47 +166,88 @@ void sqlite_datasource::bind() const
}
{
/*
XXX - This is problematic, if we do not have at least a row,
we cannot determine the right columns types and names
as all column_type are SQLITE_NULL
*/
std::ostringstream s;
s << "SELECT " << fields_ << " FROM (" << table_ << ") LIMIT 1";
boost::scoped_ptr<sqlite_resultset> rs (dataset_->execute_query (s.str()));
if (rs->is_valid () && rs->step_next())
// should we deduce column names and types using PRAGMA?
bool use_pragma_table_info = true;
if (table_ != geometry_table_)
{
for (int i = 0; i < rs->column_count (); ++i)
// if 'table_' is a subquery then we try to deduce names
// and types from the first row returned from that query
use_pragma_table_info = false;
}
if (!use_pragma_table_info)
{
std::ostringstream s;
s << "SELECT " << fields_ << " FROM (" << table_ << ") LIMIT 1";
boost::scoped_ptr<sqlite_resultset> rs (dataset_->execute_query (s.str()));
if (!rs->is_valid () && !rs->step_next())
{
const int type_oid = rs->column_type (i);
const char* fld_name = rs->column_name (i);
switch (type_oid)
{
case SQLITE_INTEGER:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Integer));
break;
case SQLITE_FLOAT:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Double));
break;
case SQLITE_TEXT:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::String));
break;
case SQLITE_NULL:
case SQLITE_BLOB:
break;
default:
#ifdef MAPNIK_DEBUG
std::clog << "Sqlite Plugin: unknown type_oid=" << type_oid << std::endl;
#endif
break;
// if we do not have at least a row,
// we cannot determine the right columns types and names
// as all column_type are SQLITE_NULL
// so we fallback to using PRAGMA table_info
use_pragma_table_info = true;
}
else
{
for (int i = 0; i < rs->column_count (); ++i)
{
const int type_oid = rs->column_type (i);
const char* fld_name = rs->column_name (i);
switch (type_oid)
{
case SQLITE_INTEGER:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Integer));
break;
case SQLITE_FLOAT:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Double));
break;
case SQLITE_TEXT:
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::String));
break;
case SQLITE_NULL:
// sqlite reports based on value, not actual column type unless
// PRAGMA table_info is used so here we assume the column is a string
// which is a lesser evil than altogether dropping the column
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::String));
case SQLITE_BLOB:
break;
default:
#ifdef MAPNIK_DEBUG
std::clog << "Sqlite Plugin: unknown type_oid=" << type_oid << std::endl;
#endif
break;
}
}
}
}
}
if (use_pragma_table_info)
{
std::ostringstream s;
s << "PRAGMA table_info(" << geometry_table_ << ")";
boost::scoped_ptr<sqlite_resultset> rs (dataset_->execute_query (s.str()));
while (rs->is_valid () && rs->step_next())
{
const char* fld_name = rs->column_text(1);
std::string fld_type(rs->column_text(2));
if (fld_type == "integer")
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Integer));
else if (fld_type == "real")
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::Double));
else if (fld_type == "text")
desc_.add_descriptor(attribute_descriptor(fld_name,mapnik::String));
//else if (fld_name == "blob")
//else if (fld_name == "null")
}
}
}

8
plugins/input/sqlite/sqlite_featureset.cpp
View file

@ -96,9 +96,15 @@ feature_ptr sqlite_featureset::next()
boost::put(*feature,fld_name,ustr);
break;
}
case SQLITE_NULL:
{
UnicodeString ustr = tr_->transcode ("");
boost::put(*feature,fld_name,ustr);
break;
}
case SQLITE_BLOB:
case SQLITE_NULL:
break;
default: