This section provides instructions on how to initialize the WalletKit client, approve sessions with supported namespaces, and respond to session requests, enabling easy integration of Web3 wallets with dapps through a simple and intuitive interface.

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Content

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Initialization: Creating a new WalletKit instance and initializing it with a projectId from Cloud.

Session: Connection between a dapp and a wallet.

  • Namespace Builder: Namespace Builder is a helper utility that greatly reduces the complexity of parsing the required and optional namespaces. It accepts as parameters a session proposal along with your user’s chains/methods/events/accounts and returns a ready-to-use object
  • Session Approval: Approving a session sent from a dapp
  • Session Rejection: Rejecting a session sent from a dapp
  • Responding to Session Requests: Responding to session requests sent from a dapp
  • Updating a Session: Updating a session sent between a dapp and wallet
  • Extending a Session: Extending a session between a dapp and wallet
  • Session Disconnect: Disconnecting a session between a dapp and wallet

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Initialization

First you must setup a Core instance with a specific Name and ProjectId. You may optionally specify other CoreOption values, such as RelayUrl and Storage

var options = new CoreOptions()
{
    ProjectId = "...",
    Name = "my-app",
}

var core = new CoreClient(options);

Next, you must define a Metadata object which describes your Wallet. This includes a Name, Description, Url and Icons url.

var metadata = new Metadata()
{
    Description = "An example wallet to showcase WalletKit",
    Icons = new[] { "https://walletconnect.com/meta/favicon.ico" },
    Name = $"wallet-csharp-test",
    Url = "https://walletconnect.com",
};

Once you have both the Core and Metadata objects, you can initialize the WalletKitClient

var sdk = await WalletKitClient.Init(core, metadata, metadata.Name);

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Session

A session is a connection between a dapp and a wallet. It is established when a user approves a session proposal from a dapp. A session is active until the user disconnects from the dapp or the session expires.

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Namespace Builder

To build a namespace mapping for either proposing a session OR approving a session, you can use .NET dictionary + class constructors directly, or use the built-in builder methods

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C# Constructor Style

var TestNamespaces = new Namespaces()
{
    {
        "eip155", new Namespace()
            {
                Accounts = new [] { "eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb" },
                Chains = new []{ "eip155:1" },
                Methods = new[] { "eth_signTransaction" },
                Events = new[] { "chainChanged" }
            }
    },
};

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Builder Style

var TestNamespaces = new Namespaces()
  .WithNamespace("eip155", new Namespace()
      .WithChain("eip155:1")
      .WithMethod("eth_signTransaction")
      .WithEvent("chainChanged")
      .WithAccount("eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb")
  );

The Namespaces mapping is required when approving a proposed session from a dApp. Because of this, you may also construct a Namespaces from a RequiredNamespaces, which auto-populates all Methods, Events and Chains from the given RequiredNamespaces. This is provided for convenience.

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RequiredNamespaces

sdk.SessionProposed += async (sender, @event) =>
{
    var proposal = @event.Proposal;
    var requiredNamespaces = proposal.RequiredNamespaces;
    var approvedNamespaces = new Namespaces(requiredNamespaces);
    approvedNamespaces["eip155"].WithAccount("eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb");
};

The RequiredNamespaces is required when setting up a session between a dApp and Wallet. The dApp will provide a RequiredNamespaces when proposing the session. The RequiredNamespaces and ProposedNamespace use the same style constructors + builder functions as Namespaces and Namespace.

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EVM methods & events

In @walletconnect/ethereum-provider, (our abstracted EVM SDK for apps) we support by default the following Ethereum methods and events:

{
  //...
  methods: [
    "eth_accounts",
    "eth_requestAccounts",
    "eth_sendRawTransaction",
    "eth_sign",
    "eth_signTransaction",
    "eth_signTypedData",
    "eth_signTypedData_v3",
    "eth_signTypedData_v4",
    "eth_sendTransaction",
    "personal_sign",
    "wallet_switchEthereumChain",
    "wallet_addEthereumChain",
    "wallet_getPermissions",
    "wallet_requestPermissions",
    "wallet_registerOnboarding",
    "wallet_watchAsset",
    "wallet_scanQRCode",
    "wallet_sendCalls",
    "wallet_getCallsStatus",
    "wallet_showCallsStatus",
    "wallet_getCapabilities",
  ],
  events: [
    "chainChanged",
    "accountsChanged",
    "message",
    "disconnect",
    "connect",
  ]
}

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Session Approval

Wallets can pair an incoming session using the session’s Uri. Pairing a session lets the Wallet obtain the connection proposal which can then be approved or denied.

var uri = "...";
await sdk.Pair(uri);

The wallet can then approve the proposal by constructing an approved Namespaces. The approved Namespaces should include the RequiredNamespaces under proposal.RequiredNamespaces, and may optionally include any optional namespaces specified under proposal.OptionalNamespaces

sdk.SessionProposed += async (sender, @event) =>
{
    var proposal = @event.Proposal;
    var requiredNamespaces = proposal.RequiredNamespaces;
    var approvedNamespaces = new Namespaces(requiredNamespaces);
    approvedNamespaces["eip155"].WithAccount("eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb");

    var sessionData = await sdk.ApproveSession(proposal.Id, approvedNamespaces);
    var sessionTopic = sessionData.Topic;
};

You may also just provide the addresses that will connect, and the SDK will create this approved Namespaces for you. This function will not approve optional namespaces

sdk.SessionProposed += async (sender, @event) =>
{
    var proposal = @event.Proposal;

    var sessionData = await sdk.ApproveSession(proposal, new[] { "eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb" });
    var sessionTopic = sessionData.Topic;
};

or

sdk.SessionProposed += async (sender, @event) =>
{
    var proposal = @event.Proposal;

    var sessionData = await sdk.ApproveSession(proposal, "eip155:1:0xab16a96d359ec26a11e2c2b3d8f8b8942d5bfcdb");
    var sessionTopic = sessionData.Topic;
};

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Session Rejection

The wallet can reject the proposal using the following:

sdk.SessionProposed += async (sender, @event) =>
{
    var proposal = @event.Proposal;
    await sdk.RejectSession(proposal, "User rejected");
};

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Responding to Session requests

Responding to session requests is very similar to sending session requests. See dApp usage on how sending session requests works. All custom session requests requires a request class and response class to be created that matches the params field type in the custom session request. C# is a static typed language, so these types must be given whenever you do a session request (or do any querying for session requests).

Currently, WalletKit does not automatically assume the object type for params is an array. This is very important, since most EVM RPC requests have params as an array type. Use List<T> to workaround this. For example, for eth_sendTransaction, use List<Transaction> instead of Transaction.

Newtonsoft.Json is used for JSON serialization/deserialization, therefore you can use Newtonsoft.Json attributes when defining fields in your request/response classes.

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Building a Response type

Create a class for the response and populate it with the JSON properties the response object has. For this example, we will use eth_getTransactionReceipt

The params field for eth_getTransactionReceipt has the object type

using Newtonsoft.Json;
using System.Numerics;

[RpcMethod("eth_getTransactionReceipt"), RpcRequestOptions(Clock.ONE_MINUTE, 99995)]
public class TransactionReceipt
{
    [JsonProperty("transactionHash")]
    public string TransactionHash;

    [JsonProperty("transactionIndex")]
    public BigInteger TransactionIndex;

    [JsonProperty("blockHash")]
    public string BlockHash;

    [JsonProperty("blockNumber")]
    public BigInteger BlockNumber;

    [JsonProperty("from")]
    public string From;

    [JsonProperty("to")]
    public string To;

    [JsonProperty("cumulativeGasUsed")]
    public BigInteger CumulativeGasUsed;

    [JsonProperty("effectiveGasPrice ")]
    public BigInteger EffectiveGasPrice ;

    [JsonProperty("gasUsed")]
    public BigInteger GasUsed;

    [JsonProperty("contractAddress")]
    public string ContractAddress;

    [JsonProperty("logs")]
    public object[] Logs;

    [JsonProperty("logsBloom")]
    public string LogBloom;

    [JsonProperty("type")]
    public BigInteger Type;

    [JsonProperty("status")]
    public BigInteger Status;
}

The RpcMethod class attributes defines the rpc method this response uses, this is optional. The RpcResponseOptions class attributes define the expiry time and tag attached to the response, this is required.

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Sending a response

To respond to requests from a dApp, you must define the class representing the request object type. The request type for eth_getTransactionReceipt is the following:

[RpcMethod("eth_getTransactionReceipt"), RpcRequestOptions(Clock.ONE_MINUTE, 99994)]
public class EthGetTransactionReceipt : List<string>
{
    public EthGetTransactionReceipt(params string[] hashes) : base(hashes)
    {
    }

    // needed for proper json deserialization
    public EthGetTransactionReceipt()
    {
    }
}

We can handle the eth_getTransactionReceipt session request by doing the following:

walletClient.Engine.SessionRequestEvents<EthGetTransactionReceipt, TransactionReceipt>().OnRequest += OnEthTransactionReceiptRequest;

private Task OnEthTransactionReceiptRequest(RequestEventArgs<EthGetTransactionReceipt, TransactionReceipt> e)
{
    // logic for request goes here
    // set e.Response to return a response
}

The callback function gets invoked whenever the wallet receives the eth_getTransactionReceipt request from a connected dApp. You may optionally filter further which requests are handled using the FilterRequests function

walletClient.Engine.SessionRequestEvents<EthGetTransactionReceipt, TransactionReceipt>()
    .FilterRequests(r => r.Topic == sessionTopic)
    .OnRequest += OnEthTransactionReceiptRequest;

The callback returns a Task, so the callback can be made async. To return a response, you must set the Response field in RequestEventArgs<T, TR> with the desired response.

private async Task OnEthTransactionReceiptRequest(RequestEventArgs<EthGetTransactionReceipt, TransactionReceipt> e)
{
    var txHash = e.Request.Params[0];
    var receipt = await EthGetTransactionReceipt(txHash);
    e.Response = receipt;
}

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Updating a Session

Update a session, adding/removing additional namespaces in the given topic.

var newNamespaces = new Namespaces(...);
var request = await walletClient.UpdateSession(sessionTopic, newNamespaces);
await request.Acknowledged();

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Extending a Session

Extend a session’s expiry time so the session remains open

var request = await walletClient.Extend(sessionTopic);
await request.Acknowledged();

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Session Disconnect

To disconnect a session, use the Disconnect function. You may optional provide a reason for the disconnect.

Disconnecting requires the topic of the session to be given. This can be found in the SessionStruct object given when a session has been given approval by the Wallet.

var sessionTopic = sessionData.Topic;
await walletClient.Disconnect(sessionTopic);

// or

await walletClient.Disconnect(sessionTopic, Error.FromErrorType(ErrorType.USER_DISCONNECTED));