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:

./src/mutation/schema.graphql

type Mutation {
  ...

  setIpfsData(
    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:

./src/mutation/schema.graphql

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

type Mutation {
  ...

tip

Implement the `setIpfsData` mutation#

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

./src/mutation/index.ts

import {
  Ethereum_Mutation,
  Ipfs_Mutation,
  Input_setData,
  Input_setIpfsData,
  SetIpfsDataResult,
} 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:

./src/mutation/index.ts

...

export function setIpfsData(input: Input_setIpfsData): SetIpfsDataResult {
  // 1. Upload the data to IPFS
  const ipfsHash = Ipfs_Mutation.addFile({
    data: String.UTF8.encode(input.options.data),
  });

  // 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 {
    ipfsHash,
    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.

Custom functionality: IPFS SimpleStorage#

Update the mutation schema#

Import IPFS' Polywrap mutations#

tip

Implement the setIpfsData mutation#

Implement the `setIpfsData` mutation#