Add support for reading enum variants in ABI

Author: banool

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to the Aptos TypeScript SDK will be captured in this file. T
 
 # Unreleased
 
+- Add `variants` field to `MoveStruct` now that the ABI fully describes enums.
+
 ## Added
 
 - Add JWK caching for keyless authentication with 5-minute TTL to improve performance

src/transactions/transactionBuilder/remoteAbi.ts

@@ -637,10 +637,10 @@ function parseArg(
       );
     }
 
-    // We are assuming that fieldless structs are enums, and therefore we cannot typecheck any further due
-    // to limited information from the ABI. This does not work for structs on other modules.
+    // Enums cannot be further type-checked from the ABI alone, so we pass through the raw bytes.
+    // TODO: The enum information is now present in the ABI, we could use that.
     const structDefinition = moduleAbi?.structs.find((s) => s.name === param.value.name.identifier);
-    if (structDefinition?.fields.length === 0 && arg instanceof Uint8Array) {
+    if (structDefinition?.is_enum && arg instanceof Uint8Array) {
       return new FixedBytes(arg);
     }
 

src/types/types.ts

@@ -1564,6 +1564,18 @@ export type MoveStructField = {
   type: string;
 };
 
+/**
+ * A variant of a Move enum, containing a name and its associated fields.
+ */
+export type MoveStructVariant = {
+  name: string;
+  /**
+   * Fields belonging to this variant. This will be empty if the enum variant has no
+   * fields. e.g. if enum MyEnum { A { field: u64 }, B }, then B will have no fields.
+   */
+  fields: Array<MoveStructField>;
+};
+
 /**
  * A Move module
  */
@@ -1613,9 +1625,14 @@ export type MoveStruct = {
    */
   generic_type_params: Array<MoveFunctionGenericTypeParam>;
   /**
-   * Fields associated with the struct
+   * Fields associated with the struct. Populated for regular structs, empty for enums.
    */
   fields: Array<MoveStructField>;
+  /**
+   * Variants of the enum. Populated when `is_enum` is true, empty for regular structs.
+   * Each variant has a name and can have its own set of fields.
+   */
+  variants: Array<MoveStructVariant>;
 };
 
 /**