fix: preserve undefined in deep accessor types

.changeset/quiet-bears-protect.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/table-core': patch
+---
+
+Preserve `undefined` in deep accessor value types when an optional parent key is used.

packages/table-core/package.json

@@ -47,7 +47,7 @@
     "clean": "rimraf ./build",
     "test:lib": "vitest",
     "test:lib:dev": "pnpm test:lib --watch",
-    "test:types": "tsc --noEmit",
+    "test:types": "tsc --noEmit && tsc --noEmit -p tsconfig.test-d.json",
     "build": "pnpm build:rollup && pnpm build:types",
     "build:rollup": "rollup --config rollup.config.mjs",
     "build:types": "tsc --emitDeclarationOnly"

packages/table-core/src/utils.ts

@@ -65,8 +65,9 @@ type DeepKeysPrefix<
   ? `${TPrefix}.${DeepKeys<T[TPrefix], [...TDepth, any]> & string}`
   : never
 
-export type DeepValue<T, TProp> =
-  T extends Record<string | number, any>
+export type DeepValue<T, TProp> = T extends null | undefined
+  ? undefined
+  : T extends Record<string | number, any>
     ? TProp extends `${infer TBranch}.${infer TDeepProp}`
       ? DeepValue<T[TBranch], TDeepProp>
       : T[TProp & string]

packages/table-core/tests/columnHelper.test-d.ts

@@ -0,0 +1,27 @@
+import { createColumnHelper } from '../src'
+
+type Expect<T extends true> = T
+type Equal<T, U> =
+  (<G>() => G extends T ? 1 : 2) extends <G>() => G extends U ? 1 : 2
+    ? true
+    : false
+
+type Row = {
+  user: {
+    salary?: {
+      amount: number
+    }
+  }
+}
+
+const columnHelper = createColumnHelper<Row>()
+
+columnHelper.accessor('user.salary.amount', {
+  cell: (info) => {
+    const amount = info.getValue()
+
+    type _ = Expect<Equal<typeof amount, number | undefined>>
+
+    return amount
+  },
+})

packages/table-core/tsconfig.test-d.json

@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true,
+    "rootDir": "."
+  },
+  "include": ["src/**/*", "tests/**/*.test-d.ts"]
+}