From 70697be8c01ef7cbc361951fad730f8181826718 Mon Sep 17 00:00:00 2001
From: Alexander Skvortsov <sasha.skvortsov109@gmail.com>
Date: Sun, 9 Aug 2020 19:03:10 -0400
Subject: [PATCH] infrastructure: (mostly) force re-calling oninit when a route
 change is handled by the same component

- Due to mithril 2.0, setting a route will not re-call oninit if the component handling the route has not changed.
- Mithril allows us to provide an options parameter to m.route.set, which, if has the state.key parameter changed, will force a re-oninit. However, manually implementing this on every button and component is both tedious, and will make further changes in functionality difficult
- To that end, we can add in this patch here, which will take care of most cases. Code that explicitly calls m.route.set will still need to include this options parameter.
---
 js/src/common/utils/patchMithril.js | 33 ++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/js/src/common/utils/patchMithril.js b/js/src/common/utils/patchMithril.js
index 8cdc852ac..bed246240 100644
--- a/js/src/common/utils/patchMithril.js
+++ b/js/src/common/utils/patchMithril.js
@@ -3,18 +3,47 @@ import Stream from 'mithril/stream';
 export default function patchMithril(global) {
   const defaultMithril = global.m;
 
+  /**
+   * Due to mithril 2.0, setting a route will not re-call oninit if the component handling the route has not changed.
+   * We, however, want to keep this behavior since it's more intuitive to users (clicking home should refresh home).
+   * Mithril allows us to provide an options parameter to m.route.set, which, if has the state.key parameter changed,
+   * will force a re-oninit. See:
+   *
+   * - https://github.com/MithrilJS/mithril.js/blob/ff3e12e5d398f653b2d0ea182a1fc963473d47f6/api/router.js#L217
+   * - https://mithril.js.org/route.html#mrouteset
+   * - https://mithril.js.org/keys.html
+   *
+   * However, manually implementing this on every button and component is both tedious, and will make further changes in
+   * functionality difficult to implement at scale, so we patch it here. The original behavior can be replicated by passing
+   * an empty object as the "options" attr to a link component.
+   *
+   * Please note that any code that manually calls m.route.set will need to provide something like this to the
+   * options parameter itself. Patching m.route.set would be more convenient, but would too severely restrict flexibility
+   */
+  const defaultLinkView = defaultMithril.route.Link.view;
+  const modifiedLink = {
+    view: function (vnode) {
+      if (!vnode.attrs.options) vnode.attrs.options = { state: { key: Date.now() } };
+
+      return defaultLinkView(vnode);
+    }
+  };
+
   const modifiedMithril = function (comp, ...args) {
     const node = defaultMithril.apply(this, arguments);
 
     if (!node.attrs) node.attrs = {};
 
+    // Allows the use of the bidi attr.
     if (node.attrs.bidi) {
       modifiedMithril.bidi(node, node.attrs.bidi);
     }
 
+    // Allows us to use a "route" attr on links, which will automatically convert the link to one which
+    // supports linking to other pages in the SPA without refreshing the document.
     if (node.attrs.route) {
       node.attrs.href = node.attrs.route;
-      node.tag = defaultMithril.route.Link;
+      node.tag = modifiedLink;
 
       delete node.attrs.route;
     }
@@ -24,6 +53,8 @@ export default function patchMithril(global) {
 
   Object.keys(defaultMithril).forEach((key) => (modifiedMithril[key] = defaultMithril[key]));
 
+  modifiedMithril.route.Link = modifiedLink;
+
   modifiedMithril.stream = Stream;
 
   global.m = modifiedMithril;