Implementing (approximately) fulltext search

routes/foods.js

@@ -9,36 +9,81 @@ router.get('/', function(req, res) {
   if ( ! query) {
     res.json([]);
   }
-  // Save a lowercase version of the query.
-  var lcQuery = query.toLowerCase();
   // Read load foods JSON from file.
   fs.readFile('sample_data/foods.json', null, function (err, data) {
     if (err) {
       res.status(500).send("Error loading locations.");
     } else {
       var foods = JSON.parse(data);
       // Filter by search term.
-      var filteredFoods = foods.filter(filterSearchResult);
+      var filteredFoods = filterSearchResult(query, foods);
       res.json(filteredFoods);
     }
   });
 
   /**
-   * Super simple search: "Does food object contain query string in any of its attributes?"
-   * TODO: Break query up by word.
-   * @param food
-   * @returns {boolean}
+   * Two-pass, multi-field search. Combines all fields
+   *   into one searchable string, then checks to see if:
+   *   (1) The query appears in order within a single field
+   *   (2) The fields (combined) contain all words of the query.
+   *   Results satisfying (1) are given first, then (2).
+   *
+   * @param {string} query
+   * @param {array} foods
+   * @returns {array} filteredFoods
    */
-  function filterSearchResult(food)
+  function filterSearchResult(query, foods)
   {
-    for(value in food) {
-      if (food[value].toLowerCase().match(lcQuery)) {
-        return true;
+    query = query.trim();
+
+    // Prefer matches in order
+    var bestRegex = new RegExp(RegExp.quote(query), 'i');
+
+    // Also accept arbitrarily ordered keywords
+    var words = query.split(/\W/);
+    var regex = '';
+    for (var i = 0; i < words.length; i++) {
+      if (words[i]) {
+        regex += '(?=.*' + RegExp.quote(words[i]) + ')';
       }
     }
-    return false;
+    regex = new RegExp(regex, 'i');
+
+    var results = [];
+    var bestResults = [];
+
+    // Iterate over each food, concatenate the fields,
+    //  and search against the result.
+    for (var i = 0; i < foods.length; i++) {
+      var text = [];
+      for (var value in foods[i]) {
+        text.push(foods[i][value]);
+      }
+      text = text.join(' | ');
+
+      // Results where the query matches a single field,
+      //  in order, are shown first.
+      if (text.match(bestRegex)) {
+        bestResults.push(foods[i]);
+      } else if (text.match(regex)) {
+        results.push(foods[i]);
+      }
+    }
+
+    // Return best results first, then the rest.
+    return bestResults.concat(results);
   }
 
+  /**
+   * Escape characters for inclusion in a regular expression.
+   * @param  {string} unescaped
+   * @return {string} escaped
+   */
+  RegExp.quote = function (string)
+  {
+    return string.replace(/[-\\^$*+?.()|[\]{}]/g, "\\$&");
+  };
+
 });
 
 module.exports = router;