Solicitudes de Transacción

Las solicitudes de transacción permiten flujos de pago interactivos al permitir que las billeteras se comuniquen con tu servidor para componer cualquier transacción de Solana. Esto desbloquea casos de uso avanzados como acuñación de NFT, precios dinámicos, transacciones DeFi de múltiples pasos y lógica empresarial personalizada.

Descripción General

Las solicitudes de transacción siguen este formato de URL:

solana:<server-endpoint-url>

La billetera realiza dos solicitudes HTTP a tu endpoint:

Solicitud GET - Recuperar información de pago (etiqueta, icono)
Solicitud POST - Obtener la transacción para firmar

Configuración Básica

1. Instalar Dependencias

pnpm add @solana/pay@beta @solana/kit @solana-program/system \
  @solana/kit-plugin-rpc @solana/kit-plugin-payer @solana/kit-plugin-instruction-plan

2. Crear Endpoint de API

Configura un endpoint de API que maneje tanto solicitudes GET como POST:

// pages/api/pay.ts (Next.js) or similar endpoint
import { address, createNoopSigner, lamports } from "@solana/kit";
import { getTransferSolInstruction } from "@solana-program/system";
import { createMerchantClient } from "@solana/pay";

const MERCHANT_WALLET = address(process.env.MERCHANT_WALLET);

export default async function handler(req, res) {
  if (req.method === "GET") {
    return handleGet(req, res);
  }

  if (req.method === "POST") {
    return handlePost(req, res);
  }

  return res.status(405).json({ error: "Method not allowed" });
}

// GET request handler
async function handleGet(req, res) {
  const label = "My Store";
  const icon = "https://mystore.com/icon.png";

  res.status(200).json({
    label,
    icon
  });
}

// POST request handler
async function handlePost(req, res) {
  try {
    const { account } = req.body;

    if (!account) {
      return res.status(400).json({ error: "Missing account parameter" });
    }

    const buyerAddress = address(account);

    // Create the merchant client for building the transaction
    const merchant = createMerchantClient({
      rpcUrl: process.env.SOLANA_RPC_URL
    });

    // Build transfer instruction (createNoopSigner because the wallet signs later)
    const instruction = getTransferSolInstruction({
      source: createNoopSigner(buyerAddress),
      destination: MERCHANT_WALLET,
      amount: lamports(100_000_000n) // 0.1 SOL
    });

    // Build a base64-encoded transaction
    const transaction = merchant.pay.buildTransaction(buyerAddress, [
      instruction
    ]);

    res.status(200).json({
      transaction,
      message: "Thanks for your purchase!"
    });
  } catch (error) {
    console.error("Transaction creation error:", error);
    res.status(500).json({ error: "Failed to create transaction" });
  }
}

3. Crear URL de Pago

Genera la URL de solicitud de transacción:

import { encodeURL } from "@solana/pay";

// Your API endpoint
const apiUrl = "https://yoursite.com/api/pay";

// Create transaction request URL
const url = encodeURL({
  link: new URL(apiUrl)
});

console.log(url.toString());
// Output: solana:https://yoursite.com/api/pay

Del Lado de la Billetera: Obtener Solicitudes de Transacción

Del lado de la billetera, utiliza fetchTransaction para recuperar y firmar una transacción desde una URL de solicitud de transacción:

import { createWalletClient } from "@solana/pay";

const wallet = createWalletClient({
  rpcUrl: "https://api.mainnet-beta.solana.com",
  payer: myWalletSigner
});

// Parse the Solana Pay URL
const parsed = wallet.pay.parseURL(url);

if ("link" in parsed) {
  // This is a transaction request — fetch the transaction from the server
  const transaction = await wallet.pay.fetchTransaction(
    myWalletSigner.address,
    parsed.link
  );
  // Sign and send the transaction...
}

Ejemplos Avanzados

Pago con Token SPL

Crea una transacción para un pago en USDC:

import { address } from "@solana/kit";
import {
  fetchMint,
  findAssociatedTokenPda,
  getTransferCheckedInstruction,
  TOKEN_PROGRAM_ADDRESS
} from "@solana-program/token";

async function createTokenPaymentInstruction(rpc, buyer, amount) {
  const USDC_MINT = address("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v");

  // Get mint info for decimals
  const mint = await fetchMint(rpc, USDC_MINT);

  // Derive associated token accounts
  const [buyerATA] = await findAssociatedTokenPda({
    owner: buyer,
    tokenProgram: TOKEN_PROGRAM_ADDRESS,
    mint: USDC_MINT
  });
  const [merchantATA] = await findAssociatedTokenPda({
    owner: MERCHANT_WALLET,
    tokenProgram: TOKEN_PROGRAM_ADDRESS,
    mint: USDC_MINT
  });

  // Calculate token amount with decimals
  const tokenAmount = BigInt(Math.round(amount * 10 ** mint.data.decimals));

  return getTransferCheckedInstruction({
    source: buyerATA,
    mint: USDC_MINT,
    destination: merchantATA,
    authority: buyer,
    amount: tokenAmount,
    decimals: mint.data.decimals
  });
}

Precios Dinámicos con Descuentos

Implementa precios dinámicos basados en datos del cliente:

async function handlePost(req, res) {
  const { account } = req.body;
  const buyer = address(account);

  // Check if customer holds discount NFT
  const hasDiscountNFT = await checkForDiscountNFT(buyer);

  // Calculate dynamic price
  let price = 10; // $10 base price
  if (hasDiscountNFT) {
    price = price * 0.8; // 20% discount
  }

  const merchant = createMerchantClient({
    rpcUrl: process.env.SOLANA_RPC_URL
  });
  const instruction = await createTokenPaymentInstruction(
    merchant.rpc,
    buyer,
    price
  );
  const transaction = merchant.pay.buildTransaction(buyer, [instruction]);

  const message = hasDiscountNFT
    ? `20% discount applied! Total: $${price.toFixed(2)}`
    : `Total: $${price.toFixed(2)}`;

  res.status(200).json({ transaction, message });
}

Integración de Gestión de Pedidos

Integra con tu sistema de pedidos existente:

import { address, AccountRole, createNoopSigner, lamports } from "@solana/kit";

// Enhanced POST handler with order management
async function handlePost(req, res) {
  const { account } = req.body;
  const { orderId } = req.query;

  if (!orderId) {
    return res.status(400).json({ error: "Missing order ID" });
  }

  // Get order details
  const order = await db.orders.findById(orderId);
  if (!order || order.status !== "pending") {
    return res.status(400).json({ error: "Invalid order" });
  }

  const buyer = address(account);

  // Create payment instruction (createNoopSigner because the wallet signs later)
  const instruction = getTransferSolInstruction({
    source: createNoopSigner(buyer),
    destination: MERCHANT_WALLET,
    amount: lamports(BigInt(Math.round(order.total * 1e9)))
  });

  // Add reference for tracking (accounts is readonly, so spread into a new instruction)
  const withRef = {
    ...instruction,
    accounts: [
      ...(instruction.accounts ?? []),
      {
        address: address(order.referenceKey),
        role: AccountRole.READONLY
      }
    ]
  };

  const merchant = createMerchantClient({ rpcUrl: process.env.SOLANA_RPC_URL });
  const transaction = merchant.pay.buildTransaction(buyer, [withRef]);

  // Update order status
  await db.orders.update(orderId, {
    status: "processing",
    walletAddress: account
  });

  res.status(200).json({
    transaction,
    message: `Order ${order.id} - ${order.items.length} items`
  });
}

Validación de Pagos

Valida las transacciones completadas:

import { address } from "@solana/kit";
import { createMerchantClient } from "@solana/pay";

const merchant = createMerchantClient({
  rpcUrl: "https://api.mainnet-beta.solana.com"
});

async function validatePayment(reference, recipient, amount) {
  try {
    const found = await merchant.pay.findReference(reference);

    // findReference only locates a signature mentioning the reference address.
    // validateTransfer checks recipient, amount, and token match.
    await merchant.pay.validateTransfer(found.signature, {
      recipient,
      amount,
      reference
    });

    return {
      success: true,
      signature: found.signature
    };
  } catch (error) {
    console.error("Payment validation error:", error);
  }

  return { success: false };
}

Manejo de Errores

Implementa un manejo robusto de errores:

async function handlePost(req, res) {
  try {
    const { account } = req.body;

    if (!account) {
      return res.status(400).json({
        error: "Missing account parameter",
        code: "MISSING_ACCOUNT"
      });
    }

    let buyer;
    try {
      buyer = address(account);
    } catch {
      return res.status(400).json({
        error: "Invalid account address",
        code: "INVALID_ACCOUNT"
      });
    }

    const instruction = getTransferSolInstruction({
      source: createNoopSigner(buyer),
      destination: MERCHANT_WALLET,
      amount: lamports(100_000_000n)
    });

    const merchant = createMerchantClient({
      rpcUrl: process.env.SOLANA_RPC_URL
    });
    const transaction = merchant.pay.buildTransaction(buyer, [instruction]);

    res.status(200).json({
      transaction,
      message: "Payment ready"
    });
  } catch (error) {
    console.error("Transaction request error:", error);

    res.status(500).json({
      error: "Internal server error",
      code: "INTERNAL_ERROR"
    });
  }
}

Mejores Prácticas

Seguridad

Valida todos los parámetros de entrada
Calcula los montos únicamente del lado del servidor
Usa HTTPS para todos los endpoints
Implementa limitación de tasa
Almacena los datos sensibles de forma segura

Rendimiento

Almacena en caché los datos de acceso frecuente
Usa agrupación de conexiones
Implementa tiempos de espera para las solicitudes
Considera usar webhooks para la confirmación de pagos

Experiencia de Usuario

Proporciona mensajes de error claros
Muestra el progreso de la transacción
Maneja los problemas de red de manera elegante
Soporta reintentos de transacción

Tabla de Contenidos