feat(graphql): add graphql fetcher for shapes as encoded polylines

re ibi-group/datatools-ui#627

src/main/java/com/conveyal/gtfs/graphql/GraphQLGtfsSchema.java

@@ -5,6 +5,7 @@
 import com.conveyal.gtfs.graphql.fetchers.JDBCFetcher;
 import com.conveyal.gtfs.graphql.fetchers.MapFetcher;
 import com.conveyal.gtfs.graphql.fetchers.NestedJDBCFetcher;
+import com.conveyal.gtfs.graphql.fetchers.PolylineFetcher;
 import com.conveyal.gtfs.graphql.fetchers.RowCountFetcher;
 import com.conveyal.gtfs.graphql.fetchers.SQLColumnFetcher;
 import com.conveyal.gtfs.graphql.fetchers.SourceObjectFetcher;
@@ -164,6 +165,12 @@ public class GraphQLGtfsSchema {
             .field(MapFetcher.field("point_type", GraphQLInt))
             .build();
 
+    // Represents a set of rows from shapes.txt joined by shape_id
+    public static final GraphQLObjectType shapeType = newObject().name("shape")
+        .field(string("shape_id"))
+        .field(string("polyline"))
+        .build();
+
 
     // Represents rows from frequencies.txt
     public static final GraphQLObjectType frequencyType =  newObject().name("frequency")
@@ -644,6 +651,20 @@ public class GraphQLGtfsSchema {
                     // DataFetchers can either be class instances implementing the interface, or a static function reference
                     .dataFetcher(new JDBCFetcher("patterns"))
                     .build())
+            .field(newFieldDefinition()
+                .name("shapes")
+                .type(new GraphQLList(shapeType))
+                .argument(intArg(ID_ARG))
+                .argument(intArg(LIMIT_ARG))
+                .argument(intArg(OFFSET_ARG))
+                .argument(floatArg(MIN_LAT))
+                .argument(floatArg(MIN_LON))
+                .argument(floatArg(MAX_LAT))
+                .argument(floatArg(MAX_LON))
+                .argument(multiStringArg("shape_id"))
+                // DataFetchers can either be class instances implementing the interface, or a static function reference
+                .dataFetcher(new PolylineFetcher())
+                .build())
             // Then the fields for the sub-tables within the feed (loaded directly from GTFS).
             .field(newFieldDefinition()
                     .name("agency")
@@ -798,8 +819,6 @@ public class GraphQLGtfsSchema {
             .newSchema()
             .query(feedQuery)
 //            .query(patternsForStopQuery)
-            // TODO: Add mutations.
-            // .mutation(someMutation)
             .build();
 
 

src/main/java/com/conveyal/gtfs/graphql/fetchers/PolylineFetcher.java

@@ -0,0 +1,87 @@
+package com.conveyal.gtfs.graphql.fetchers;
+
+import com.conveyal.gtfs.graphql.GTFSGraphQL;
+import com.conveyal.gtfs.util.PolylineUtils;
+import graphql.schema.DataFetcher;
+import graphql.schema.DataFetchingEnvironment;
+import org.apache.commons.dbutils.DbUtils;
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.GeometryFactory;
+import org.locationtech.jts.geom.Point;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * GraphQL fetcher to get encoded polylines for all shapes in a GTFS feed.
+ */
+public class PolylineFetcher implements DataFetcher {
+    public static final Logger LOG = LoggerFactory.getLogger(PolylineFetcher.class);
+
+    @Override
+    public Object get(DataFetchingEnvironment environment) {
+        GeometryFactory gf = new GeometryFactory();
+        List<Shape> shapes = new ArrayList<>();
+        Map<String, Object> parentFeedMap = environment.getSource();
+        String namespace = (String) parentFeedMap.get("namespace");
+        Connection connection = null;
+        try {
+            connection = GTFSGraphQL.getConnection();
+            Statement statement = connection.createStatement();
+            String sql = String.format(
+                "select shape_id, shape_pt_lon, shape_pt_lat from %s.shapes order by shape_id",
+                namespace
+            );
+            LOG.info("SQL: {}", sql);
+            if (statement.execute(sql)) {
+                ResultSet result = statement.getResultSet();
+                String currentShapeId = null;
+                String nextShapeId;
+                List<Point> shapePoints = new ArrayList<>();
+                while (result.next()) {
+                    // Get values from SQL row.
+                    nextShapeId = result.getString(1);
+                    double lon = result.getDouble(2);
+                    double lat = result.getDouble(3);
+                    if (currentShapeId != null && !nextShapeId.equals(currentShapeId)) {
+                        // Finish current shape if new shape_id is encountered.
+                        shapes.add(new Shape(currentShapeId, shapePoints));
+                        // Start building new shape.
+                        shapePoints = new ArrayList<>();
+                    }
+                    // Update current shape_id and add shape point to list.
+                    currentShapeId = nextShapeId;
+                    shapePoints.add(gf.createPoint(new Coordinate(lon, lat)));
+                }
+                // Add the final shape when result iteration is finished.
+                shapes.add(new Shape(currentShapeId, shapePoints));
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        } finally {
+            DbUtils.closeQuietly(connection);
+        }
+        return shapes;
+    }
+
+    /**
+     * Simple class to return shapes for GraphQL response format.
+     */
+    public static class Shape {
+        public String shape_id;
+        public String polyline;
+
+        public Shape(String shape_id, List<Point> shapePoints) {
+            this.shape_id = shape_id;
+            // Encode the shapepoints as a polyline
+            this.polyline = PolylineUtils.encode(shapePoints, 6);
+        }
+    }
+}