Fixed ability to query tasks collection using task ID. Fixes #68.

lib/nbi.coffee

@@ -348,6 +348,7 @@ listener = (request, response) ->
         else
           q = {}
         q = query.expand(q, aliases) if collectionName is 'devices'
+        q = query.substituteObjectId(q) if collectionName is 'tasks'
 
         if urlParts.query.projection?
           projection = {}

lib/query.coffee

@@ -22,6 +22,7 @@
 
 common = require './common'
 normalize = require './normalize'
+mongodb = require 'mongodb'
 
 
 expandValue = (param, value) ->
@@ -103,5 +104,30 @@ expand = (query, aliases) ->
 
   return new_query
 
+# Replace _id string values with ObjectID type
+substituteObjectId = (query) ->
+  for k, v of query
+    if k[0] == '$' # logical operator
+      for i in [0...v.length]
+        substituteObjectId(v[i])
+    else if k == '_id'
+      if common.typeOf(v) is common.STRING_TYPE
+        query[k] = mongodb.ObjectID(v) if v.length == 24
+      else if common.typeOf(v) is common.OBJECT_TYPE
+        for kk, vv of v
+          switch kk # operator
+            when '$in', '$nin'
+              for i in [0...vv.length]
+                vv[i] = mongodb.ObjectID(vv[i]) if vv[i].length == 24
+            when '$eq', '$gt', '$gte', '$lt', '$lte', '$ne'
+              v[kk] = mongodb.ObjectID(vv) if vv.length == 24
+            when '$exists', '$type' then
+              # ignore
+            else
+              throw new Error('Operator not supported')
+
+  return query
+
 
 exports.expand = expand
+exports.substituteObjectId = substituteObjectId