Don't flatten filtered objects

src/app/hooks/canFlatten.ts

@@ -0,0 +1,23 @@
+import { Hook } from '@mcschema/core'
+import { getFilterKey } from './getFilterKey'
+
+export const canFlatten: Hook<[], boolean> = {
+  base: () => false,
+  boolean: () => false,
+  choice: () => false,
+  list: () => false,
+  map: () => false,
+  number: () => false,
+  string: () => false,
+  object({ node, getActiveFields }, path) {
+    const filterKey = path.modelArr.length === 0 ? null : node.hook(getFilterKey, path, path)
+    const visibleEntries = Object.entries(getActiveFields(path))
+      .filter(([k, v]) => filterKey !== k && v.enabled(path))
+    if (visibleEntries.length !== 1) return false
+
+    const nestedPath = path.push(visibleEntries[0][0])
+    if (visibleEntries[0][1].type(nestedPath) !== 'object') return false
+
+    return visibleEntries[0][1].hook(getFilterKey, nestedPath, nestedPath) === null
+  }
+}

src/app/hooks/customValidation.ts

@@ -1,5 +1,5 @@
 import { Errors, Hook, relativePath } from '@mcschema/core'
-import { App, BlockStateRegistry } from '../App'
+import { App } from '../App'
 import { getFilterKey } from './getFilterKey'
 import { walk } from './walk'
 

src/app/hooks/renderHtml.ts

@@ -4,8 +4,9 @@ import { Mounter } from '../views/View'
 import { hexId, htmlEncode } from '../Utils'
 import { suffixInjector } from './suffixInjector'
 import { Octicon } from '../components/Octicon'
-import { App, BlockStateRegistry } from '../App'
+import { App } from '../App'
 import { getFilterKey } from './getFilterKey'
+import { canFlatten } from './canFlatten'
 
 /**
  * Secondary model used to remember the keys of a map
@@ -189,7 +190,7 @@ export const renderHtml: Hook<[any, Mounter], [string, string, string]> = {
           : activeKeys)
         .filter(k => filterKey !== k)
         .filter(k => activeFields[k].enabled(path))
-      if (visibleKeys.length === 1 && activeFields[visibleKeys[0]].type(path.push(visibleKeys[0])) === 'object') {
+      if (node.hook(canFlatten, path)) {
         const newValue = value[visibleKeys[0]] ?? {}
         body = activeFields[visibleKeys[0]].hook(this, path.push(visibleKeys[0]), newValue, mounter)[2]
       } else {

tsconfig.json

@@ -3,6 +3,7 @@
     "target": "es6",
     "lib": [
       "dom",
+      "es2017.object",
       "es2019"
     ],
     "module": "esnext",