From 85e4955f9a1a050bd76306688ae2b2702ea9b311 Mon Sep 17 00:00:00 2001
From: Florian Mounier <florian.mounier@kozea.fr>
Date: Tue, 19 Jun 2018 16:23:46 +0200
Subject: [PATCH] Allow number knob to be empty (returns null instead of 0).
 Prevent uncontrolled to controlled warning when defaulting to null (or
 undefined).

---
 addons/knobs/src/components/types/Number.js | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/addons/knobs/src/components/types/Number.js b/addons/knobs/src/components/types/Number.js
index 829d327810e3..1c2fe118a3d1 100644
--- a/addons/knobs/src/components/types/Number.js
+++ b/addons/knobs/src/components/types/Number.js
@@ -39,10 +39,11 @@ const RangeWrapper = styled('div')({
 class NumberType extends React.Component {
   constructor(props) {
     super(props);
-
-    this.state = {
-      value: props.knob.value,
-    };
+    let { value } = props.knob;
+    if (value === null || value === undefined) {
+      value = '';
+    }
+    this.state = { value };
 
     this.onChange = debounce(props.onChange, 400);
   }
@@ -58,7 +59,7 @@ class NumberType extends React.Component {
 
     let parsedValue = Number(value);
 
-    if (Number.isNaN(parsedValue)) {
+    if (Number.isNaN(parsedValue) || value === '') {
       parsedValue = null;
     }
 
@@ -110,7 +111,7 @@ NumberType.propTypes = {
   onChange: PropTypes.func,
 };
 
-NumberType.serialize = value => String(value);
-NumberType.deserialize = value => parseFloat(value);
+NumberType.serialize = value => (value === null || value === undefined ? '' : String(value));
+NumberType.deserialize = value => (value === '' ? null : parseFloat(value));
 
 export default NumberType;