Export omitDefault to help build Amino JSON converters

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to
   `sign`/`signAndBroadcast`/`signAndBroadcastSync` and related functions now
   have an additional parameter to specify the timeout height. After this height,
   a signed transaction will be considered invalid by the chain. ([#1489])
+- @cosmjs/amino: Export `omitDefault` to help build Amino JSON converters.
 
 [#1489]: https://github.com/cosmos/cosmjs/pull/1489
 

packages/amino/src/index.ts

@@ -14,6 +14,7 @@ export {
   encodeSecp256k1Pubkey,
 } from "./encoding";
 export { createMultisigThresholdPubkey } from "./multisig";
+export { omitDefault } from "./omitdefault";
 export { makeCosmoshubPath } from "./paths";
 export {
   Ed25519Pubkey,

packages/amino/src/omitdefault.spec.ts

@@ -0,0 +1,23 @@
+import { omitDefault } from "./omitdefault";
+
+describe("omitDefault", () => {
+  it("works for numbers", () => {
+    expect(omitDefault(17)).toEqual(17);
+    expect(omitDefault(0)).toEqual(undefined);
+  });
+
+  it("works for bigint", () => {
+    expect(omitDefault(17n)).toEqual(17n);
+    expect(omitDefault(0n)).toEqual(undefined);
+  });
+
+  it("works for boolean", () => {
+    expect(omitDefault(true)).toEqual(true);
+    expect(omitDefault(false)).toEqual(undefined);
+  });
+
+  it("works for strings", () => {
+    expect(omitDefault("hi")).toEqual("hi");
+    expect(omitDefault("")).toEqual(undefined);
+  });
+});

packages/amino/src/omitdefault.ts

@@ -0,0 +1,18 @@
+/**
+ * Returns the given input. If the input is the default value
+ * of protobuf, undefined is retunred. Use this when creating Amino JSON converters.
+ */
+export function omitDefault<T extends string | number | bigint | boolean>(input: T): T | undefined {
+  switch (typeof input) {
+    case "string":
+      return input === "" ? undefined : input;
+    case "number":
+      return input === 0 ? undefined : input;
+    case "bigint":
+      return input === BigInt(0) ? undefined : input;
+    case "boolean":
+      return !input ? undefined : input;
+    default:
+      throw new Error(`Got unsupported type '${typeof input}'`);
+  }
+}

packages/stargate/src/modules/ibc/aminomessages.ts

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-import { AminoMsg, Coin } from "@cosmjs/amino";
+import { AminoMsg, Coin, omitDefault } from "@cosmjs/amino";
 import { MsgTransfer } from "cosmjs-types/ibc/applications/transfer/v1/tx";
 
 import { AminoConverters } from "../../aminotypes";
@@ -45,22 +45,6 @@ export function isAminoMsgTransfer(msg: AminoMsg): msg is AminoMsgTransfer {
   return msg.type === "cosmos-sdk/MsgTransfer";
 }
 
-function omitDefault<T extends string | number | bigint>(input: T): T | undefined {
-  if (typeof input === "string") {
-    return input === "" ? undefined : input;
-  }
-
-  if (typeof input === "number") {
-    return input === 0 ? undefined : input;
-  }
-
-  if (typeof input === "bigint") {
-    return input === BigInt(0) ? undefined : input;
-  }
-
-  throw new Error(`Got unsupported type '${typeof input}'`);
-}
-
 export function createIbcAminoConverters(): AminoConverters {
   return {
     "/ibc.applications.transfer.v1.MsgTransfer": {