Bugfix: Create attributes of the features on the Mapnik context

Otherwise Mapnik gets not attributes and any attribute filters return
false.

src/mbtiles_vector_datasource.cpp

@@ -260,14 +260,26 @@ void mbtiles_vector_datasource::parse_json()
     //TODO init bounds
 }
 
+mapnik::context_ptr mbtiles_vector_datasource::get_context_with_attributes() const
+{
+    mapnik::context_ptr context = std::make_shared<mapnik::context_type>();
+    const std::vector<mapnik::attribute_descriptor>& desc_ar = desc_.get_descriptors();
+    for (auto const& attr_info : desc_ar)
+    {
+        context->push(attr_info.get_name()); // TODO only push query attributes
+    }
+    return context;
+}
+
 mapnik::featureset_ptr mbtiles_vector_datasource::features(mapnik::query const& q) const
 {
 #ifdef MAPNIK_STATS
     mapnik::progress_timer __stats__(std::clog, "mbtiles_vector_datasource::features");
 #endif
 
     mapnik::box2d<double> const& box = q.get_bbox();
-    return mapnik::featureset_ptr(new mbtiles_vector_featureset(dataset_, zoom_, box, layer_));
+    mapnik::context_ptr context = get_context_with_attributes();
+    return mapnik::featureset_ptr(new mbtiles_vector_featureset(dataset_, context, zoom_, box, layer_));
 }
 
 mapnik::featureset_ptr mbtiles_vector_datasource::features_at_point(mapnik::coord2d const& pt, double tol) const
@@ -277,6 +289,6 @@ mapnik::featureset_ptr mbtiles_vector_datasource::features_at_point(mapnik::coor
 #endif
 
     mapnik::filter_at_point filter(pt, tol);
-
-    return mapnik::featureset_ptr(new mbtiles_vector_featureset(dataset_, zoom_, filter.box_, layer_));
+    mapnik::context_ptr context = get_context_with_attributes();
+    return mapnik::featureset_ptr(new mbtiles_vector_featureset(dataset_, context, zoom_, filter.box_, layer_));
 }

src/mbtiles_vector_datasource.hpp

@@ -59,6 +59,7 @@ class mbtiles_vector_datasource : public mapnik::datasource
 
 private:
     void init(mapnik::parameters const& params);
+    mapnik::context_ptr get_context_with_attributes() const;
     int zoom_from_string(const char* z);
     int zoom_from_string(const std::string& z);
     void parse_json();

src/mbtiles_vector_featureset.cpp

@@ -11,9 +11,10 @@
 #include <math.h>
 
 mbtiles_vector_featureset::mbtiles_vector_featureset(std::shared_ptr<sqlite_connection> database,
-        const int zoom,
+        mapnik::context_ptr const& ctx, const int zoom,
         mapnik::box2d<double> const& extent, const std::string & layer) :
                database_(database),
+               context_(ctx),
                zoom_(zoom),
                extent_(extent),
                layer_(layer),
@@ -89,15 +90,14 @@ bool mbtiles_vector_featureset::open_tile()
     {
         return false;
     }
-    std::cerr << "Opening vector tile " << zoom_ << '/' << x_ << '/' << y_ << '\n';
     if (mapnik::vector_tile_impl::is_gzip_compressed(blob, size) ||
         mapnik::vector_tile_impl::is_zlib_compressed(blob, size))
     {
         std::string decompressed;
         mapnik::vector_tile_impl::zlib_decompress(blob, size, decompressed);
-        vector_tile_.reset(new mvt_io(std::move(decompressed), x_, y_, zoom_, layer_));
+        vector_tile_.reset(new mvt_io(std::move(decompressed), context_, x_, y_, zoom_, layer_));
     } else {
-        vector_tile_.reset(new mvt_io(std::string(blob, size), x_, y_, zoom_, layer_));
+        vector_tile_.reset(new mvt_io(std::string(blob, size), context_, x_, y_, zoom_, layer_));
     }
     return true;
 }

src/mbtiles_vector_featureset.hpp

@@ -35,6 +35,7 @@ class mbtiles_vector_featureset : public mapnik::Featureset
 {
 public:
     mbtiles_vector_featureset(std::shared_ptr<sqlite_connection> database,
+        mapnik::context_ptr const& ctx,
         const int zoom,
         mapnik::box2d<double> const& extent,
         const std::string & layer);
@@ -44,6 +45,7 @@ class mbtiles_vector_featureset : public mapnik::Featureset
 private:
     bool valid() const;
     std::shared_ptr<sqlite_connection> database_;
+    mapnik::context_ptr context_;
     int zoom_;
     mapnik::box2d<double> const& extent_;
     const std::string& layer_;

src/mvt_io.cpp

@@ -12,11 +12,12 @@
 #include <stdexcept>
 
 
-mvt_layer::mvt_layer(const uint32_t x, const uint32_t y, const uint32_t zoom)
+mvt_layer::mvt_layer(const uint32_t x, const uint32_t y, const uint32_t zoom,
+        mapnik::context_ptr const& ctx)
     : keys_(),
     values_(),
-    tr_("utf-8"),
-    ctx_(std::make_shared<mapnik::context_type>())
+    context_(ctx),
+    tr_("utf-8")
 {
     resolution_ = mapnik::EARTH_CIRCUMFERENCE / (1 << zoom);
     tile_x_ = -0.5 * mapnik::EARTH_CIRCUMFERENCE + x * resolution_;
@@ -71,7 +72,7 @@ mapnik::feature_ptr mvt_layer::next_feature()
     {
         const protozero::data_view d (features_.at(feature_index_));
         protozero::pbf_reader f (d);
-        mapnik::feature_ptr feature = mapnik::feature_factory::create(ctx_, feature_index_);
+        mapnik::feature_ptr feature = mapnik::feature_factory::create(context_, feature_index_);
         ++feature_index_;
         mvt_message::geom_type geometry_type = mvt_message::geom_type::unknown;
         bool has_geometry = false;
@@ -166,7 +167,7 @@ mapnik::feature_ptr mvt_layer::next_feature()
 
 bool mvt_io::read_layer(protozero::pbf_message<mvt_message::layer>& pbf_layer)
 {
-    layer_.reset(new mvt_layer(x_, y_, zoom_));
+    layer_.reset(new mvt_layer(x_, y_, zoom_, context_));
     bool ignore_layer = false;
     while (pbf_layer.next())
     {
@@ -264,8 +265,9 @@ mapnik::feature_ptr mvt_io::next()
     return layer_->next_feature();
 }
 
-mvt_io::mvt_io(std::string&& data, const uint32_t x, const uint32_t y, const uint32_t zoom, std::string layer_name)
+mvt_io::mvt_io(std::string&& data, mapnik::context_ptr const& ctx, const uint32_t x, const uint32_t y, const uint32_t zoom, std::string layer_name)
         : reader_(data),
+        context_(ctx),
         x_(x),
         y_(y),
         zoom_(zoom),

src/mvt_io.hpp

@@ -68,18 +68,18 @@ class mvt_layer
     size_t feature_index_ = 0;
     std::vector<std::string> keys_;
     std::vector<pbf_attr_value_type> values_;
+    mapnik::context_ptr const& context_;
     std::size_t num_keys_ = 0;
     std::size_t num_values_ = 0;
     mapnik::transcoder tr_;
-    mapnik::context_ptr ctx_;
     double tile_x_;
     double tile_y_;
     double resolution_;
     double scale_ = 0;
     std::string name_;
     uint32_t extent_ = 4096;
 public:
-    explicit mvt_layer(const uint32_t x, const uint32_t y, const uint32_t zoom);
+    explicit mvt_layer(const uint32_t x, const uint32_t y, const uint32_t zoom, mapnik::context_ptr const& ctx);
     void add_feature(const protozero::data_view& feature);
     bool has_features() const;
     void add_key(std::string&& key);
@@ -95,6 +95,7 @@ class mvt_layer
 class mvt_io
 {
     protozero::pbf_reader reader_;
+    mapnik::context_ptr context_;
     const uint32_t x_;
     const uint32_t y_;
     const uint32_t zoom_;
@@ -108,7 +109,7 @@ class mvt_io
     bool read_layer(protozero::pbf_message<mvt_message::layer>& l);
 
 public:
-    explicit mvt_io(std::string&& data, const uint32_t x, const uint32_t y, const uint32_t zoom, std::string layer_name);
+    explicit mvt_io(std::string&& data, mapnik::context_ptr const& ctx, const uint32_t x, const uint32_t y, const uint32_t zoom, std::string layer_name);
     mapnik::feature_ptr next();
 };