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Adding new mutation functions

Custom functionality: IPFS SimpleStorage#

It's time to build and customizing your own Polywrapper! We'll be adding IPFS support to the SimpleStorage Polywrap.

A complete project with the modifications described below can be found here.

Update the mutation schema#

The first step to adding new Polywrapper functionality is defining the method we want our users to query in GraphQL. Add the following method & custom data types to your ./src/mutation/schema.graphql schema file:

type Mutation {
options: SetIpfsDataOptions!
connection: Ethereum_Connection
): SetIpfsDataResult!
type SetIpfsDataOptions {
address: String!
data: String!
type SetIpfsDataResult {
ipfsHash: String!
txReceipt: String!

Import IPFS' Polywrap mutations#

Since we'll be making use of IPFS in our Polywrapper, let's import its Mutation type so we can call it from our code, allowing us to upload content:

#import { Mutation } into Ipfs from "w3://ens/ipfs.web3api.eth"
type Mutation {

Implement the setIpfsData mutation#

In the ./src/mutation/index.ts file, import the new types we've defined:

import {
} from './w3';

These new types will not exist yet, but don't worry, they'll be generated in the ./src/mutation/w3/* folder once the yarn build command is run.

Next, we'll implement the setIpfsData mutation method. Add this function to the bottom of your ./src/mutation/index.ts file:

export function setIpfsData(input: Input_setIpfsData): SetIpfsDataResult {
// 1. Upload the data to IPFS
const ipfsHash = Ipfs_Mutation.addFile({
data: String.UTF8.encode(,
// 2. Add the data's IPFS hash to SimpleStorage using `setHash(...)`
const txReceipt = Ethereum_Mutation.callContractMethodAndWait({
address: input.options.address,
method: 'function setHash(string value)',
args: [ipfsHash],
connection: input.connection,
// 3. Return the result
return {
txReceipt: txReceipt.transactionHash,

As you can see, the SimpleStorage.sol smart contract already exposes a setHash() method.

In steps 1 and 2, our SimpleStorage Polywrapper is sending a "sub-query" to the IPFS and Ethereum Polywrappers we imported within our schema. These Polywrappers can be implements as a WebAssembly-based Polywrapper, or a plugin in the client's language (ex: JavaScript). For more information on plugins, see the "Plugin an Existing JS SDK" documentation.

The Ethereum_Mutation.callContractMethodAndWait function also accepts an optional argument, connection. This option allows you to select the network in which you're transacting with, by specifying a node's endpoint, or a network (name or chain ID) (e.g. "rinkeby").

To verify everything is implemented correctly, try running yarn build and see if the Polywrap build succeeds.