select attributes recursively

src/__snapshots__/tsynamo.integration.test.ts.snap

@@ -12,6 +12,19 @@ exports[`tsynamo > query > handles a FilterExpression that uses attribute_exists
     "somethingElse": -5,
     "userId": "123",
   },
+  {
+    "dataTimestamp": 996,
+    "nested": {
+      "nestedBoolean": true,
+      "nestedNested": {
+        "nestedNestedBoolean": true,
+      },
+      "nestedString": "llol",
+    },
+    "someBoolean": false,
+    "somethingElse": -9,
+    "userId": "123",
+  },
   {
     "dataTimestamp": 999,
     "nested": {
@@ -187,6 +200,19 @@ exports[`tsynamo > query > handles a query with a NOT FilterExpression 1`] = `
     "somethingElse": 10,
     "userId": "123",
   },
+  {
+    "dataTimestamp": 996,
+    "nested": {
+      "nestedBoolean": true,
+      "nestedNested": {
+        "nestedNestedBoolean": true,
+      },
+      "nestedString": "llol",
+    },
+    "someBoolean": false,
+    "somethingElse": -9,
+    "userId": "123",
+  },
   {
     "dataTimestamp": 999,
     "nested": {
@@ -224,6 +250,19 @@ exports[`tsynamo > query > handles a query with a NOT FilterExpression 2`] = `
     "somethingElse": 10,
     "userId": "123",
   },
+  {
+    "dataTimestamp": 996,
+    "nested": {
+      "nestedBoolean": true,
+      "nestedNested": {
+        "nestedNestedBoolean": true,
+      },
+      "nestedString": "llol",
+    },
+    "someBoolean": false,
+    "somethingElse": -9,
+    "userId": "123",
+  },
 ]
 `;
 
@@ -272,6 +311,19 @@ exports[`tsynamo > query > handles a query with a simple KeyCondition 1`] = `
     "somethingElse": 10,
     "userId": "123",
   },
+  {
+    "dataTimestamp": 996,
+    "nested": {
+      "nestedBoolean": true,
+      "nestedNested": {
+        "nestedNestedBoolean": true,
+      },
+      "nestedString": "llol",
+    },
+    "someBoolean": false,
+    "somethingElse": -9,
+    "userId": "123",
+  },
   {
     "dataTimestamp": 999,
     "nested": {
@@ -302,6 +354,19 @@ exports[`tsynamo > query > handles a query with multiple expressions 1`] = `
 
 exports[`tsynamo > query > handles conditions on nested keys 1`] = `
 [
+  {
+    "dataTimestamp": 996,
+    "nested": {
+      "nestedBoolean": true,
+      "nestedNested": {
+        "nestedNestedBoolean": true,
+      },
+      "nestedString": "llol",
+    },
+    "someBoolean": false,
+    "somethingElse": -9,
+    "userId": "123",
+  },
   {
     "dataTimestamp": 999,
     "nested": {

src/tsynamo.integration.test.ts

@@ -19,6 +19,9 @@ interface DDB {
     nested: {
       nestedString: number;
       nestedBoolean: boolean;
+      nestedNested: {
+        nestedNestedBoolean: boolean;
+      };
     };
   };
   myOtherTable: {
@@ -112,7 +115,23 @@ describe("tsynamo", () => {
       );
       expect(Object.keys(data!).length).toBe(2);
     });
-    it.todo("handles selecting nested attributes excessively deep");
+    it("handles selecting nested attributes excessively deep", async () => {
+      const data = await tsynamoClient
+        .getItemFrom("myTable")
+        .keys({
+          userId: TEST_ITEM_9.userId,
+          dataTimestamp: TEST_ITEM_9.dataTimestamp,
+        })
+        .consistentRead(true)
+        .attributes(["someBoolean", "nested.nestedNested.nestedNestedBoolean"])
+        .execute();
+
+      expect(data?.someBoolean).toBe(TEST_ITEM_9.someBoolean);
+      expect(data?.nested?.nestedNested?.nestedNestedBoolean).toBe(
+        TEST_ITEM_9.nested.nestedNested.nestedNestedBoolean
+      );
+      expect(Object.keys(data!).length).toBe(2);
+    });
     it.todo("handles selecting attributes from arrays");
 
     it("can't await instance directly", async () => {
@@ -139,7 +158,7 @@ describe("tsynamo", () => {
         .keyCondition("userId", "=", TEST_ITEM_1.userId)
         .execute();
 
-      expect(data?.length).toBe(4);
+      expect(data?.length).toBe(5);
       expect(data).toMatchSnapshot();
     });
 
@@ -356,6 +375,19 @@ const TEST_ITEM_8 = {
     nestedBoolean: true,
   },
 };
+const TEST_ITEM_9 = {
+  userId: "123",
+  dataTimestamp: 996,
+  somethingElse: -9,
+  someBoolean: false,
+  nested: {
+    nestedString: "llol",
+    nestedBoolean: true,
+    nestedNested: {
+      nestedNestedBoolean: true,
+    },
+  },
+};
 
 /**
  * Re-create a DynamoDB table called "myTable" with some test data.
@@ -482,4 +514,10 @@ const setupTestDatabase = async (client: DynamoDBDocumentClient) => {
       Item: TEST_ITEM_8,
     })
   );
+  await client.send(
+    new PutCommand({
+      TableName: "myTable",
+      Item: TEST_ITEM_9,
+    })
+  );
 };

src/typeHelpers.ts

@@ -65,24 +65,31 @@ export type SelectAttributesRaw<
 > = {
   [A in Attributes[number]]: Table[A];
 };
+export type UnionToIntersection<U> = (
+  U extends any ? (k: U) => void : never
+) extends (k: infer I) => void
+  ? I
+  : never;
 
-type NestedValue<T, K extends string> = K extends `${infer First}.${infer Rest}`
-  ? First extends keyof T
-    ? { [k in Rest]: NestedValue<T[First], Rest> }
+type RecursiveSelectAttributes<Table, Properties> = Properties extends [
+  infer First,
+  ...infer Rest
+]
+  ? First extends keyof Table
+    ? { [key in First]: RecursiveSelectAttributes<Table[First], Rest> }
     : never
-  : K extends keyof T
-  ? T[K]
-  : never;
+  : Table;
 
-// TODO make this Recursive
 export type SelectAttributes<
   Table,
   Attributes extends ReadonlyArray<string>
-> = {
-  [A in Attributes[number] as A extends `${infer First}.${infer _}`
-    ? First
-    : A]: NestedValue<Table, A>;
-};
+> = IntersectionToSingleObject<
+  UnionToIntersection<
+    RecursiveSelectAttributes<Table, ParsePath<Attributes[number]>>
+  >
+>;
+
+type a = ParsePath<"a.b[1].c" | "a.a.b">;
 
 export type DeepPartial<T> = {
   [P in keyof T]?: T[P] extends Array<infer U>
@@ -91,6 +98,9 @@ export type DeepPartial<T> = {
     ? DeepPartial<T[P]>
     : T[P];
 };
+type IntersectionToSingleObject<T> = T extends infer U
+  ? { [K in keyof U]: U[K] }
+  : never;
 
 // We first need to parse the path string into a list of Properties,
 // Then, we recursively access Properties on the input object.