mapnik/plugins/input/postgis/postgis_featureset.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2024 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#include "postgis_featureset.hpp"
#include "resultset.hpp"
#include "cursorresultset.hpp"
#include "numeric2string.hpp"

// mapnik
#include <mapnik/global.hpp>
#include <mapnik/debug.hpp>
#include <mapnik/wkb.hpp>
#include <mapnik/unicode.hpp>
#include <mapnik/value/types.hpp>
#include <mapnik/feature_factory.hpp>
#include <mapnik/util/conversions.hpp>
#include <mapnik/util/trim.hpp>
#include <mapnik/global.hpp> // for int2net

// stl
#include <sstream>
#include <string>
#include <memory>

using mapnik::context_ptr;
using mapnik::feature_factory;
using mapnik::geometry_utils;

postgis_featureset::postgis_featureset(std::shared_ptr<IResultSet> const& rs,
                                       context_ptr const& ctx,
                                       std::string const& encoding,
                                       bool key_field,
                                       bool key_field_as_attribute,
                                       bool twkb_encoding)
    : rs_(rs)
    , ctx_(ctx)
    , tr_(new transcoder(encoding))
    , totalGeomSize_(0)
    , feature_id_(1)
    , key_field_(key_field)
    , key_field_as_attribute_(key_field_as_attribute)
    , twkb_encoding_(twkb_encoding)
{}

feature_ptr postgis_featureset::next()
{
    while (rs_->next())
    {
        // new feature
        unsigned pos = 1;
        feature_ptr feature;

        if (key_field_)
        {
            std::string name = rs_->getFieldName(pos);

            // null feature id is not acceptable
            if (rs_->isNull(pos))
            {
                MAPNIK_LOG_WARN(postgis) << "postgis_featureset: null value encountered for key_field: " << name;
                continue;
            }
            // create feature with user driven id from attribute
            int oid = rs_->getTypeOID(pos);
            const char* buf = rs_->getValue(pos);

            // validation happens of this type at initialization
            mapnik::value_integer val;

            if (oid == 20)
            {
                val = int8net(buf);
            }
            else if (oid == 21)
            {
                val = int2net(buf);
            }
            else
            {
                val = int4net(buf);
            }

            feature = feature_factory::create(ctx_, val);
            if (key_field_as_attribute_)
            {
                feature->put<mapnik::value_integer>(name, val);
            }
            ++pos;
        }
        else
        {
            // fallback to auto-incrementing id
            feature = feature_factory::create(ctx_, feature_id_);
            ++feature_id_;
        }

        // null geometry is not acceptable
        if (rs_->isNull(0))
        {
            MAPNIK_LOG_WARN(postgis) << "postgis_featureset: null value encountered for geometry";
            continue;
        }

        // parse geometry
        int size = rs_->getFieldLength(0);
        const char* data = rs_->getValue(0);

        if (twkb_encoding_)
        {
            feature->set_geometry(geometry_utils::from_twkb(data, size));
        }
        else
        {
            feature->set_geometry(geometry_utils::from_wkb(data, size));
        }

        totalGeomSize_ += size;
        unsigned num_attrs = ctx_->size() + 1;
        if (!key_field_as_attribute_)
        {
            num_attrs++;
        }
        for (; pos < num_attrs; ++pos)
        {
            std::string name = rs_->getFieldName(pos);

            // NOTE: we intentionally do not store null here
            // since it is equivalent to the attribute not existing
            if (!rs_->isNull(pos))
            {
                const char* buf = rs_->getValue(pos);
                const int oid = rs_->getTypeOID(pos);
                switch (oid)
                {
                    case 16: // bool
                    {
                        feature->put(name, (buf[0] != 0));
                        break;
                    }

                    case 23: // int4
                    {
                        feature->put<mapnik::value_integer>(name, int4net(buf));
                        break;
                    }

                    case 21: // int2
                    {
                        feature->put<mapnik::value_integer>(name, int2net(buf));
                        break;
                    }

                    case 20: // int8/BigInt
                    {
                        feature->put<mapnik::value_integer>(name, int8net(buf));
                        break;
                    }

                    case 700: // float4
                    {
                        float val;
                        float4net(val, buf);
                        feature->put(name, static_cast<double>(val));
                        break;
                    }

                    case 701: // float8
                    {
                        double val;
                        float8net(val, buf);
                        feature->put(name, val);
                        break;
                    }

                    case 25:   // text
                    case 1043: // varchar
                    case 705:  // literal
                    {
                        feature->put(name, tr_->transcode(buf));
                        break;
                    }

                    case 1042: // bpchar
                    {
                        std::string str = mapnik::util::trim_copy(buf);
                        feature->put(name, tr_->transcode(str.c_str()));
                        break;
                    }

                    case 1700: // numeric
                    {
                        double val;
                        std::string str = numeric2string(buf);
                        if (mapnik::util::string2double(str, val))
                        {
                            feature->put(name, val);
                        }
                        break;
                    }

                    default: {
                        MAPNIK_LOG_WARN(postgis) << "postgis_featureset: Unknown type_oid=" << oid;

                        break;
                    }
                }
            }
        }
        return feature;
    }
    return feature_ptr();
}

postgis_featureset::~postgis_featureset()
{
    rs_->close();
}