add _.omitted to omit properties (#78)

README.md

@@ -394,6 +394,18 @@ var user = {
 var result = u({ user: u.omit(['authToken', 'SSN']) }, user);
 
 expect(result).to.eql({ user: { email: 'john@aol.com', username: 'john123' } });
+
+### `u.omitted`
+
+A property updated to this constant will be removed from the final object.
+Useful when one wishes to remove and update properties in a single operation.
+
+```js
+var user = { email: 'john@aol.com', username: 'john123', authToken: '1211..' };
+
+var result = u({ authToken: u.omitted, active: true }, user);
+
+expect(result).to.eql({ user: { email: 'john@aol.com', username: 'john123', active: true } });
 ```
 
 ### `u.omitBy(predicate(, object))`
@@ -414,6 +426,7 @@ function isSensitive(value, key) { return key == 'SSN' }
 var result = u({ user: u.omitBy(isSensitive) }, user);
 
 expect(result).to.eql({ user: { email: 'john@aol.com', username: 'john123', authToken: '1211..' } });
+
 ```
 
 ### `u.reject(predicate(, object))`

lib/index.js

@@ -7,7 +7,7 @@ import map from './map'
 import omit from './omit'
 import omitBy from './omitBy'
 import reject from './reject'
-import update from './update'
+import update, { omitted } from './update'
 import updateIn from './updateIn'
 import withDefault from './withDefault'
 import { _ } from './util/curry'
@@ -26,6 +26,7 @@ u.omitBy = omitBy
 u.reject = reject
 u.update = update
 u.updateIn = updateIn
+u.omitted = omitted
 u.withDefault = withDefault
 
 module.exports = u

lib/update.js

@@ -1,5 +1,11 @@
 import isPlainObject from 'lodash/isPlainObject'
+import _omitBy from 'lodash/omitBy'
+
 import wrap from './wrap'
+import constant from './constant'
+
+const innerOmitted = { __omitted: true }
+export const omitted = constant(innerOmitted)
 
 function isEmpty(object) {
   return !Object.keys(object).length
@@ -84,10 +90,15 @@ function update(updates, object, ...args) {
   }
 
   if (Array.isArray(defaultedObject)) {
-    return updateArray(resolvedUpdates, defaultedObject)
+    return updateArray(resolvedUpdates, defaultedObject).filter(
+      value => value !== innerOmitted
+    )
   }
 
-  return { ...defaultedObject, ...resolvedUpdates }
+  return _omitBy(
+    { ...defaultedObject, ...resolvedUpdates },
+    value => value === innerOmitted
+  )
 }
 
 export default wrap(update, 2)

test/updeep-spec.js

@@ -142,4 +142,33 @@ describe('updeep', () => {
     const result = u({ created: date }, {})
     expect(result).to.eql({ created: date })
   })
+
+  const expectU = (update, orig, expected) =>
+    expect(update(orig)).to.eql(expected)
+
+  describe('u.omitted', () => {
+    it('omit properties via u.omitted', () => {
+      expectU(u({ a: u.omitted, b: i => i + 1 }), { a: 1, b: 2 }, { b: 3 })
+    })
+
+    it('omit array and object properties', () => {
+      expectU(
+        u({ a: u.omitted, b: 'stuff', c: u.omitted }),
+        { a: [1, 2, 3], b: 'orig', c: { z: 'bar' } },
+        { b: 'stuff' }
+      )
+    })
+
+    it('deep omit', () => {
+      expectU(
+        u({ a: { b: u.omitted, c: 'stuff' } }),
+        { a: { b: 'foo', z: 'bar' } },
+        { a: { z: 'bar', c: 'stuff' } }
+      )
+    })
+
+    it('omitting an array item filters it out', () => {
+      expectU(u({ 1: u.omitted }), ['a', 'b', 'c'], ['a', 'c'])
+    })
+  })
 })