Remove duplicate query-based predicates code

Author: c-w

services/features.js

@@ -122,15 +122,21 @@ function buildQueryColumns(query) {
     return queryColumns;
 }
 
+function addQueryPredicates(sql, query) {
+    if (query.layer) {
+        sql += ` AND layer = ${escapeSql(query.layer)}`;
+    }
+
+    return sql;
+}
+
 function getByBoundingBox(query, callback) {
     let boundingBoxQuery = `SELECT ${buildQueryColumns(query)} FROM features WHERE ST_Intersects(hull, ST_MakeEnvelope(
         ${query.west}, ${query.south},
         ${query.east}, ${query.north}, 4326
     ))`;
 
-    if (query.layer) {
-        boundingBoxQuery += ` AND layer=${escapeSql(query.layer)}`;
-    }
+    boundingBoxQuery = addQueryPredicates(boundingBoxQuery, query);
 
     return executeQuery(boundingBoxQuery, callback);
 }
@@ -140,9 +146,7 @@ function getByPoint(query, callback) {
         'POINT(${query.longitude} ${query.latitude})', 4326)
     )`;
 
-    if (query.layer) {
-        pointQuery += ` AND layer=${escapeSql(query.layer)}`;
-    }
+    pointQuery = addQueryPredicates(pointQuery, query);
 
     return executeQuery(pointQuery, callback);
 }
@@ -155,9 +159,7 @@ function getByName(query, callback) {
     }).join(" OR ")})`;
     let nameQuery = `SELECT ${buildQueryColumns(query)} FROM features WHERE ${namesDisjunction}`;
 
-    if (query.layer) {
-        nameQuery += ` AND layer=${escapeSql(query.layer)}`;
-    }
+    nameQuery = addQueryPredicates(nameQuery, query);
 
     executeQuery(nameQuery, callback);
 }