feat: encodeFunctionResult

Author: jxom

.changeset/violet-humans-press.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added `encodeFunctionResult`.

site/.vitepress/sidebar.ts

@@ -474,8 +474,8 @@ export const sidebar: DefaultTheme.Sidebar = {
               link: '/docs/contract/encodeFunctionData',
             },
             {
-              text: 'encodeFunctionResult 🚧',
-              link: '/docs/contract/encodeFunctionData',
+              text: 'encodeFunctionResult',
+              link: '/docs/contract/encodeFunctionResult',
             },
           ],
         },

site/docs/contract/encodeFunctionResult.md

@@ -1,3 +1,191 @@
 # encodeFunctionResult
 
-TODO
+Encodes structured return data into ABI encoded data. It is the opposite of [`decodeFunctionResult`](/docs/contract/decodeFunctionResult).
+
+## Install
+
+```ts
+import { encodeFunctionResult } from 'viem';
+```
+
+## Usage
+
+Given an ABI (`abi`) and a function (`functionName`), pass through the values (`values`) to encode:
+
+::: code-group
+
+```ts [example.ts]
+import { encodeFunctionResult } from 'viem';
+
+const data = encodeFunctionResult({
+  abi: wagmiAbi,
+  functionName: 'ownerOf',
+  value: ['0xa5cc3c03994db5b0d9a5eedd10cabab0813678ac'],
+});
+// '0x000000000000000000000000a5cc3c03994db5b0d9a5eedd10cabab0813678ac'
+```
+
+```ts [abi.ts]
+export const wagmiAbi = [
+  ...
+  {
+    inputs: [{ name: 'tokenId', type: 'uint256' }],
+    name: 'ownerOf',
+    outputs: [{ name: '', type: 'address' }],
+    stateMutability: 'view',
+    type: 'function',
+  },
+  ...
+] as const;
+```
+
+```ts [client.ts]
+import { createPublicClient, http } from 'viem';
+import { mainnet } from 'viem/chains';
+
+export const publicClient = createPublicClient({
+  chain: mainnet,
+  transport: http(),
+});
+```
+
+:::
+
+### A more complex example
+
+::: code-group
+
+```ts [example.ts]
+import { decodeFunctionResult } from 'viem'
+
+const data = decodeFunctionResult({
+  abi: wagmiAbi,
+  functionName: 'getInfo',
+  value: [
+    {
+      foo: {
+        sender: '0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC',
+        x: 69420n,
+        y: true
+      },
+      sender: '0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC',
+      z: 69
+    }
+  ]
+})
+// 0x000000000000000000000000a5cc3c03994db5b0d9a5eedd10cabab0813678ac0000000000000000000000000000000000000000000000000000000000010f2c0000000000000000000000000000000000000000000000000000000000000001000000000000000000000000a5cc3c03994db5b0d9a5eedd10cabab0813678ac0000000000000000000000000000000000000000000000000000000000000045
+```
+
+```ts [abi.ts]
+export const wagmiAbi = [
+  ...
+  {
+    inputs: [],
+    name: 'getInfo',
+    outputs: [
+      {
+        components: [
+          {
+            components: [
+              {
+                internalType: 'address',
+                name: 'sender',
+                type: 'address',
+              },
+              {
+                internalType: 'uint256',
+                name: 'x',
+                type: 'uint256',
+              },
+              {
+                internalType: 'bool',
+                name: 'y',
+                type: 'bool',
+              },
+            ],
+            internalType: 'struct Example.Foo',
+            name: 'foo',
+            type: 'tuple',
+          },
+          {
+            internalType: 'address',
+            name: 'sender',
+            type: 'address',
+          },
+          {
+            internalType: 'uint32',
+            name: 'z',
+            type: 'uint32',
+          },
+        ],
+        internalType: 'struct Example.Bar',
+        name: 'res',
+        type: 'tuple',
+      },
+    ],
+    stateMutability: 'pure',
+    type: 'function',
+  },
+  ...
+] as const;
+```
+
+```ts [client.ts]
+import { createPublicClient, http } from 'viem';
+import { mainnet } from 'viem/chains';
+
+export const publicClient = createPublicClient({
+  chain: mainnet,
+  transport: http(),
+});
+```
+
+:::
+
+## Return Value
+
+The decoded data. Type is inferred from the ABI.
+
+## Parameters
+
+### abi
+
+- **Type:** [`Abi`](/docs/glossary/types#TODO)
+
+The contract's ABI.
+
+```ts
+const data = encodeFunctionResult({
+  abi: wagmiAbi, // [!code focus]
+  functionName: 'ownerOf',
+  value: ['0xa5cc3c03994db5b0d9a5eedd10cabab0813678ac'],
+});
+```
+
+### functionName
+
+- **Type:** `string`
+
+The function to encode from the ABI.
+
+```ts
+const data = encodeFunctionResult({
+  abi: wagmiAbi,
+  functionName: 'ownerOf', // [!code focus]
+  value: ['0xa5cc3c03994db5b0d9a5eedd10cabab0813678ac'],
+});
+```
+
+### values
+
+- **Type**: `Hex`
+
+Return values to encode.
+
+```ts
+const data = encodeFunctionResult({
+  abi: wagmiAbi,
+  functionName: 'ownerOf',
+  value: ['0xa5cc3c03994db5b0d9a5eedd10cabab0813678ac'], // [!code focus]
+});
+```

src/index.test.ts

@@ -74,6 +74,7 @@ test('exports actions', () => {
       "encodeAbi": [Function],
       "encodeBytes": [Function],
       "encodeFunctionData": [Function],
+      "encodeFunctionResult": [Function],
       "encodeHex": [Function],
       "encodeRlp": [Function],
       "estimateGas": [Function],

src/index.ts

@@ -276,6 +276,7 @@ export {
   encodeAbi,
   encodeBytes,
   encodeFunctionData,
+  encodeFunctionResult,
   encodeHex,
   encodeRlp,
   getAddress,

src/types/index.ts

@@ -40,6 +40,7 @@ export type {
   ExtractArgsFromAbi,
   ExtractArgsFromEventDefinition,
   ExtractArgsFromFunctionDefinition,
+  ExtractResultFromAbi,
 } from './solidity'
 
 export type {

src/types/solidity.ts

@@ -37,6 +37,31 @@ export type ExtractArgsFromAbi<
       /** Arguments to pass contract method */ args: TArgs
     }
 
+export type ExtractResultFromAbi<
+  TAbi extends Abi | readonly unknown[],
+  TFunctionName extends string,
+  TAbiFunction extends AbiFunction & { type: 'function' } = TAbi extends Abi
+    ? ExtractAbiFunction<TAbi, TFunctionName>
+    : AbiFunction & { type: 'function' },
+  TArgs = AbiParametersToPrimitiveTypes<TAbiFunction['outputs']>,
+  FailedToParseArgs =
+    | ([TArgs] extends [never] ? true : false)
+    | (readonly unknown[] extends TArgs ? true : false),
+> = true extends FailedToParseArgs
+  ? {
+      /**
+       * Arguments to pass contract method
+       *
+       * Use a [const assertion](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-4.html#const-assertions) on {@link abi} for type inference.
+       */
+      result?: readonly unknown[]
+    }
+  : TArgs extends readonly []
+  ? { result?: never }
+  : {
+      /** Arguments to pass contract method */ result: TArgs
+    }
+
 //////////////////////////////////////////////////////////////////////
 // Event/Function Definitions