Added omit as an eligible query parameter. omit builds a fields objec…

…t that omits specified fields and includes all others.

README.md

@@ -16,6 +16,22 @@ For example, a query such as: `name=john&age>21&fields=name,age&sort=name,-age&o
   }
 }
 ```
+The omit query parameter is used to create options: fields to exclude fields.
+For example, a query such as: `name=john&age>21&omit=name&sort=name,-age&offset=10&limit=10` becomes the following hash:
+ ```javascript
+ {
+   criteria: {
+     name: 'john',
+         age: { $gt: 21 }
+   },
+   options: {
+     fields: { age: false },
+     sort: { name: 1, age: -1 },
+     offset: 10,
+     limit: 10
+   }
+ }
+```
 The resulting query object can be used as parameters for a mongo collection query:
 ```javascript
 var q2m = require('query-to-mongo')
@@ -86,7 +102,8 @@ The format for arguments was inspired by item #7 in [this article](http://blog.m
 
 ### Field selection
 The _fields_ argument is a comma separated list of field names to include in the results. For example `fields=name,age` results in a _option.fields_ value of `{'name':true,'age':true}`. If no fields are specified then _option.fields_ is null, returning full documents as results.
-
+The _omit_ argument is a comma separated list of field names to exclude in the results. For example `omit=name,age` results in a _option.fields_ value of `{'name':false,'age':false}`. If no fields are specified then _option.fields_ is null, returning full documents as results.
+Note that either _fields_ or _omit can be used.  If both are specified then _omit_ takes precedence and the _fields_ entry is ignored.
 ### Sorting
 The _sort_ argument is a comma separated list of fields to sort the results by. For example `sort=name,-age` results in a _option.sort_ value of `{'name':1,'age':-1}`. If no sort is specified then _option.sort_ is null and the results are not sorted.
 

index.js

@@ -1,7 +1,7 @@
 var querystring = require('querystring')
 var iso8601 = require('./lib/iso8601-regex')
 
-// Convert comma separate list to a mongo projection.
+// Convert comma separated list to a mongo projection.
 // for example f('field1,field2,field3') -> {field1:true,field2:true,field3:true}
 function fieldsToMongo(fields) {
     if (!fields) return null
@@ -12,7 +12,18 @@ function fieldsToMongo(fields) {
     return hash
 }
 
-// Convert comma separate list to mongo sort options.
+// Convert comma separated list to a mongo projection which specifies fields to omit.
+// for example f('field2') -> {field2:false}
+function omitFieldsToMongo(omitFields) {
+    if (!omitFields) return null
+    var hash = {}
+    omitFields.split(',').forEach(function(omitField) {
+        hash[omitField.trim()] = false
+    })
+    return hash
+}
+
+// Convert comma separated list to mongo sort options.
 // for example f('field1,+field2,-field3') -> {field1:1,field2:1,field3:-1}
 function sortToMongo(sort) {
     if (!sort) return null
@@ -110,11 +121,13 @@ function queryCriteriaToMongo(query, options) {
 function queryOptionsToMongo(query, options) {
     var hash = {},
         fields = fieldsToMongo(query.fields),
+        omitFields = omitFieldsToMongo(query.omit),
         sort = sortToMongo(query.sort),
         maxLimit = options.maxLimit || 9007199254740992,
         limit = options.maxLimit || 0
 
     if (fields) hash.fields = fields
+    if (omitFields) hash.fields = omitFields
     if (sort) hash.sort = sort
 
     if (query.offset) hash.skip = Number(query.offset)
@@ -136,7 +149,7 @@ module.exports = function(query, options) {
     } else {
         options.ignore = (typeof options.ignore === 'string') ? [options.ignore] : options.ignore
     }
-    options.ignore = options.ignore.concat(['fields', 'sort', 'skip', 'limit'])
+    options.ignore = options.ignore.concat(['fields', 'omit', 'sort', 'skip', 'limit'])
     if (!options.parser) options.parser = querystring
 
     if (typeof query === 'string') query = options.parser.parse(query)