Switching DynamoDB scan to FilterExpression (#55)

* Switching DynamoDB scan to FilterExpression * Fixing node 0.12 compatibility
thenativeweb · Sep 27, 2017 · 38bd1f2 · 38bd1f2
1 parent 24bea37
commit 38bd1f2
Showing 1 changed file with 47 additions and 12 deletions.
diff --git a/lib/databases/dynamodb.js b/lib/databases/dynamodb.js
@@ -295,22 +295,57 @@ _.extend(DynamoDB.prototype, {
   }
 });
 
+function createDynamoParams(obj, objPrefix) {
+  objPrefix = objPrefix ? objPrefix + '.#' : '#';
+
+  return _.reduce(obj, function (result, value, key) {
+      var valueSearchedFor = obj[key];
+      var dotNotatedTargetAttribute = objPrefix + key;
+
+      if(_.isPlainObject(valueSearchedFor)) {
+          result = _.merge(result, createDynamoParams(valueSearchedFor, dotNotatedTargetAttribute));
+          result.expressionAttributeNames['#' + key] = key;
+      } else {
+          var attributeVariable = ':' + dotNotatedTargetAttribute.replace(/(\.|#)/g, '');
+          var attributeValueKey = '#' + key;
+
+          if (result.filterExpression !== '') {
+            result.filterExpression = result.filterExpression + ' AND ';
+          }
+
+          result.filterExpression = result.filterExpression + dotNotatedTargetAttribute + ' = ' + attributeVariable;
+          result.expressionAttributeValues[attributeVariable] = valueSearchedFor;
+          result.expressionAttributeNames['#' + key] = key;
+      }
+
+      return result;
+  },
+  {
+    expressionAttributeNames: {},
+    filterExpression: '',
+    expressionAttributeValues: {}
+  })
+};
+
 function queryToScanParams(tableName, query, queryOptions){
   var limit = queryOptions.skip + queryOptions.limit;
-  var scanFilter = _.reduce(query, function(result, value, key) {
-    result[key] = {
-      ComparisonOperator: 'EQ',
-      AttributeValueList: [ value]
-    };
-    return result;
-  }, {});
   var params = {
-      TableName: tableName,
-      ScanFilter: scanFilter
-  };
-  if(limit > 0){
-    return _.set(params, 'Limit', limit);
+    TableName: tableName,
+  }
+
+  if (limit > 0) {
+    params.Limit = limit;
   }
+
+  if (_.isEmpty(query)) {
+    return params;
+  }
+
+  var dynamoParams = createDynamoParams(query);
+  params.FilterExpression = dynamoParams.filterExpression;
+  params.ExpressionAttributeNames = dynamoParams.expressionAttributeNames;
+  params.ExpressionAttributeValues = dynamoParams.expressionAttributeValues;
+
   return params;
 }