DX-997: Make cursor field in scan commands string (#1115)

* fix: make return type of cursor commands string

scan commands can return a '0' or a long number as a string. If we deserialize, we get 0 from '0' and a truncated number from the long number string. Second one is non-ideal.

In this case, we want to return the cursor as a string. This means excluding the cursor from the deserialization, hence the new deserializeScanResponse method.

* fix: reorder deserialize and commandOptions

this way, overwriting deserialize will be possible.

pkg/commands/geo_search.ts

@@ -130,8 +130,8 @@ export class GeoSearchCommand<
         ...(opts?.withHash ? ["WITHHASH"] : []),
       ],
       {
-        ...commandOptions,
         deserialize: transform,
+        ...commandOptions,
       },
     );
   }

pkg/commands/hscan.test.ts

@@ -14,7 +14,7 @@ describe("without options", () => {
     const res = await new HScanCommand([key, 0]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
@@ -23,10 +23,10 @@ describe("with match", () => {
   test("returns cursor and members", async () => {
     const key = newKey();
     await new HSetCommand([key, { field: "value" }]).exec(client);
-    const res = await new HScanCommand([key, 0, { match: "field" }]).exec(client);
+    const res = await new HScanCommand([key, "0", { match: "field" }]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
@@ -35,10 +35,10 @@ describe("with count", () => {
   test("returns cursor and members", async () => {
     const key = newKey();
     await new HSetCommand([key, { field: "value" }]).exec(client);
-    const res = await new HScanCommand([key, 0, { count: 1 }]).exec(client);
+    const res = await new HScanCommand([key, "0", { count: 1 }]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });

pkg/commands/hscan.ts

@@ -1,25 +1,29 @@
+import { deserializeScanResponse } from "../util";
 import { Command, CommandOptions } from "./command";
 import { ScanCommandOptions } from "./scan";
 
 /**
  * @see https://redis.io/commands/hscan
  */
 export class HScanCommand extends Command<
-  [number, (string | number)[]],
-  [number, (string | number)[]]
+  [string, (string | number)[]],
+  [string, (string | number)[]]
 > {
   constructor(
-    [key, cursor, cmdOpts]: [key: string, cursor: number, cmdOpts?: ScanCommandOptions],
-    opts?: CommandOptions<[number, (string | number)[]], [number, (string | number)[]]>,
+    [key, cursor, cmdOpts]: [key: string, cursor: string | number, cmdOpts?: ScanCommandOptions],
+    opts?: CommandOptions<[string, (string | number)[]], [string, (string | number)[]]>,
   ) {
-    const command = ["hscan", key, cursor];
+    const command: (number | string)[] = ["hscan", key, cursor];
     if (cmdOpts?.match) {
       command.push("match", cmdOpts.match);
     }
     if (typeof cmdOpts?.count === "number") {
       command.push("count", cmdOpts.count);
     }
 
-    super(command, opts);
+    super(command, {
+      deserialize: deserializeScanResponse,
+      ...opts,
+    });
   }
 }

pkg/commands/scan.test.ts

@@ -15,13 +15,13 @@ test("without options", () => {
     const key = newKey();
     const value = randomID();
     await new SetCommand([key, value]).exec(client);
-    let cursor = 0;
+    let cursor = "0";
     const found: string[] = [];
     do {
       const res = await new ScanCommand([cursor]).exec(client);
       cursor = res[0];
       found.push(...res[1]);
-    } while (cursor !== 0);
+    } while (cursor !== "0");
     expect(found.includes(key)).toBeTrue();
   });
 });
@@ -32,14 +32,14 @@ test("with match", () => {
     const value = randomID();
     await new SetCommand([key, value]).exec(client);
 
-    let cursor = 0;
+    let cursor = "0";
     const found: string[] = [];
     do {
       const res = await new ScanCommand([cursor, { match: key }]).exec(client);
       expect(typeof res[0]).toEqual("number");
       cursor = res[0];
       found.push(...res[1]);
-    } while (cursor !== 0);
+    } while (cursor !== "0");
 
     expect(found).toEqual([key]);
   });
@@ -51,13 +51,13 @@ test("with count", () => {
     const value = randomID();
     await new SetCommand([key, value]).exec(client);
 
-    let cursor = 0;
+    let cursor = "0";
     const found: string[] = [];
     do {
       const res = await new ScanCommand([cursor, { count: 1 }]).exec(client);
       cursor = res[0];
       found.push(...res[1]);
-    } while (cursor !== 0);
+    } while (cursor !== "0");
 
     expect(found.includes(key)).toEqual(true);
   });
@@ -74,13 +74,13 @@ test("with type", () => {
     // Add a non-string type
     await new ZAddCommand([key2, { score: 1, member: "abc" }]).exec(client);
 
-    let cursor = 0;
+    let cursor = "0";
     const found: string[] = [];
     do {
       const res = await new ScanCommand([cursor, { type: "string" }]).exec(client);
       cursor = res[0];
       found.push(...res[1]);
-    } while (cursor !== 0);
+    } while (cursor !== "0");
 
     expect(found.length).toEqual(1);
     for (const key of found) {

pkg/commands/scan.ts

@@ -1,3 +1,4 @@
+import { deserializeScanResponse } from "../util";
 import { Command, CommandOptions } from "./command";
 
 export type ScanCommandOptions = {
@@ -8,12 +9,12 @@ export type ScanCommandOptions = {
 /**
  * @see https://redis.io/commands/scan
  */
-export class ScanCommand extends Command<[number, string[]], [number, string[]]> {
+export class ScanCommand extends Command<[string, string[]], [string, string[]]> {
   constructor(
-    [cursor, opts]: [cursor: number, opts?: ScanCommandOptions],
-    cmdOpts?: CommandOptions<[number, string[]], [number, string[]]>,
+    [cursor, opts]: [cursor: string | number, opts?: ScanCommandOptions],
+    cmdOpts?: CommandOptions<[string, string[]], [string, string[]]>,
   ) {
-    const command = ["scan", cursor];
+    const command: (number | string)[] = ["scan", cursor];
     if (opts?.match) {
       command.push("match", opts.match);
     }
@@ -23,6 +24,12 @@ export class ScanCommand extends Command<[number, string[]], [number, string[]]>
     if (opts?.type && opts.type.length > 0) {
       command.push("type", opts.type);
     }
-    super(command, cmdOpts);
+    super(
+      command,
+      {
+        deserialize: deserializeScanResponse,
+        ...cmdOpts,
+      }
+    );
   }
 }

pkg/commands/sscan.test.ts

@@ -1,48 +1,48 @@
 import { keygen, newHttpClient, randomID } from "../test-utils";
 
-import { afterAll, expect, test } from "bun:test";
+import { afterAll, describe, expect, test } from "bun:test";
 import { SAddCommand } from "./sadd";
 import { SScanCommand } from "./sscan";
 const client = newHttpClient();
 
 const { newKey, cleanup } = keygen();
 
 afterAll(cleanup);
-test("without options", () => {
+describe("without options", () => {
   test("returns cursor and members", async () => {
     const key = newKey();
     const member = randomID();
     await new SAddCommand([key, member]).exec(client);
     const res = await new SScanCommand([key, 0]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
 
-test("with match", () => {
+describe("with match", () => {
   test("returns cursor and members", async () => {
     const key = newKey();
     const member = randomID();
     await new SAddCommand([key, member]).exec(client);
-    const res = await new SScanCommand([key, 0, { match: member }]).exec(client);
+    const res = await new SScanCommand([key, "0", { match: member }]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
 
-test("with count", () => {
+describe("with count", () => {
   test("returns cursor and members", async () => {
     const key = newKey();
     const member = randomID();
     await new SAddCommand([key, member]).exec(client);
-    const res = await new SScanCommand([key, 0, { count: 1 }]).exec(client);
+    const res = await new SScanCommand([key, "0", { count: 1 }]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });

pkg/commands/sscan.ts

@@ -1,25 +1,32 @@
+import { deserializeScanResponse } from "../util";
 import { Command, CommandOptions } from "./command";
 import { ScanCommandOptions } from "./scan";
 
 /**
  * @see https://redis.io/commands/sscan
  */
 export class SScanCommand extends Command<
-  [number, (string | number)[]],
-  [number, (string | number)[]]
+  [string, (string | number)[]],
+  [string, (string | number)[]]
 > {
   constructor(
-    [key, cursor, opts]: [key: string, cursor: number, opts?: ScanCommandOptions],
-    cmdOpts?: CommandOptions<[number, (string | number)[]], [number, (string | number)[]]>,
+    [key, cursor, opts]: [key: string, cursor: string | number, opts?: ScanCommandOptions],
+    cmdOpts?: CommandOptions<[string, (string | number)[]], [string, (string | number)[]]>,
   ) {
-    const command = ["sscan", key, cursor];
+    const command: (number | string)[] = ["sscan", key, cursor];
     if (opts?.match) {
       command.push("match", opts.match);
     }
     if (typeof opts?.count === "number") {
       command.push("count", opts.count);
     }
 
-    super(command, cmdOpts);
+    super(
+      command,
+      {
+        deserialize: deserializeScanResponse,
+        ...cmdOpts,
+      }
+    );
   }
 }

pkg/commands/zscan.test.ts

@@ -16,7 +16,7 @@ describe("without options", () => {
     const res = await new ZScanCommand([key, 0]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
@@ -26,10 +26,10 @@ describe("with match", () => {
     const key = newKey();
     const value = randomID();
     await new ZAddCommand([key, { score: 0, member: value }]).exec(client);
-    const res = await new ZScanCommand([key, 0, { match: value }]).exec(client);
+    const res = await new ZScanCommand([key, "0", { match: value }]).exec(client);
 
     expect(res.length).toBe(2);
-    expect(typeof res[0]).toBe("number");
+    expect(typeof res[0]).toBe("string");
     expect(res![1].length > 0).toBe(true);
   });
 });
@@ -39,7 +39,7 @@ test("with count", () => {
     const key = newKey();
     const value = randomID();
     await new ZAddCommand([key, { score: 0, member: value }]).exec(client);
-    const res = await new ZScanCommand([key, 0, { count: 1 }]).exec(client);
+    const res = await new ZScanCommand([key, "0", { count: 1 }]).exec(client);
 
     expect(res.length).toBe(2);
     expect(typeof res[0]).toBe("number");

pkg/commands/zscan.ts

@@ -1,25 +1,32 @@
+import { deserializeScanResponse } from "../util";
 import { Command, CommandOptions } from "./command";
 import { ScanCommandOptions } from "./scan";
 
 /**
  * @see https://redis.io/commands/zscan
  */
 export class ZScanCommand extends Command<
-  [number, (string | number)[]],
-  [number, (string | number)[]]
+  [string, (string | number)[]],
+  [string, (string | number)[]]
 > {
   constructor(
-    [key, cursor, opts]: [key: string, cursor: number, opts?: ScanCommandOptions],
-    cmdOpts?: CommandOptions<[number, (string | number)[]], [number, (string | number)[]]>,
+    [key, cursor, opts]: [key: string, cursor: string | number, opts?: ScanCommandOptions],
+    cmdOpts?: CommandOptions<[string, (string | number)[]], [string, (string | number)[]]>,
   ) {
-    const command = ["zscan", key, cursor];
+    const command: (number | string)[] = ["zscan", key, cursor];
     if (opts?.match) {
       command.push("match", opts.match);
     }
     if (typeof opts?.count === "number") {
       command.push("count", opts.count);
     }
 
-    super(command, cmdOpts);
+    super(
+      command,
+      {
+        deserialize: deserializeScanResponse,
+        ...cmdOpts,
+      }
+    );
   }
 }

pkg/util.ts

@@ -29,3 +29,14 @@ export function parseResponse<TResult>(result: unknown): TResult {
     return result as TResult;
   }
 }
+
+/**
+ * Deserializes a scan result, excluding the cursor
+ * which can be string "0" or a big number string.
+ * Either way, we want it to stay as a string.
+ * 
+ * @param result 
+ */
+export function deserializeScanResponse<TResult>(result: [string, ...any]): TResult {
+  return [result[0], ...parseResponse<any[]>(result.slice(1))] as TResult;
+}