From 1a1a23ab3c87335d974cd5eeafff82eaade86a42 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rge=20N=C3=A6ss?= <bjoerge@gmail.com>
Date: Fri, 25 Jan 2019 14:05:45 +0100
Subject: [PATCH] [form-builder] Include note about the format of _key in the
 missing keys warning

---
 .../@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js  | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js b/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
index 18073795c04..da4e1d304be 100644
--- a/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
+++ b/packages/@sanity/form-builder/src/inputs/ArrayInput/ArrayInput.js
@@ -340,6 +340,10 @@ export default class ArrayInput extends React.Component<Props, State> {
               This usually happens when items are created through the API client from outside the
               Content Studio and someone forgets to set the <code>_key</code>-property of list
               items.
+              <p>
+                The value of the <code>_key</code> can be any <b>string</b> as long as it is{' '}
+                <b>unique</b> for each element within the array.
+              </p>
             </Details>
           </div>
           {this.renderList()}