Query a Contract Method

Use this guide to perform a read-only query against a deployed contract. Unlike a call, this does not produce a blockchain transaction and is free of gas fees.

Prerequisites

Before you begin, ensure:

• The contract ABI is uploaded
• The contract deployment is registered
• You have the deploymentId and method name

Endpoint

POST /v2/contract/deployment/{id}/query

Request Parameters

{
  "method": "balanceOf",
  "params": ["0xabc123..."]
}

• method: The name of the method to query
• params: An array of arguments in the same order as the method signature

Example Request

cURL

query-method.sh

curl -X POST https://api.fsco.io/v2/contract/deployment/dep_abc123/query \
  -H "Authorization: Bearer $FSCO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "methodName": "balanceOf",
    "paramCollection": ["0xabc"],
    "isShared": false
  }'

TypeScript

query-method.ts

import axios from 'axios';

const FSCO_API_KEY = process.env.FSCO_API_KEY;

const queryMethod = async () => {
  const response = await axios.post(
    'https://api.fsco.io/v2/contract/deployment/dep_abc123/query',
    {
      methodName: 'balanceOf',
      paramCollection: ['0xabc'],
      isShared: false
    },
    {
      headers: {
        Authorization: `Bearer ${FSCO_API_KEY}`,
        'Content-Type': 'application/json'
      }
    }
  );

  console.log('Contract query result:', response.data);
};

queryMethod();

Python

query-method.py

import requests
import os

FSCO_API_KEY = os.getenv("FSCO_API_KEY")

headers = {
    "Authorization": f"Bearer {FSCO_API_KEY}",
    "Content-Type": "application/json",
}

payload = {"methodName": "balanceOf", "paramCollection": ["0xabc"], "isShared": False}

response = requests.post(
    "https://api.fsco.io/v2/contract/deployment/dep_abc123/query",
    json=payload,
    headers=headers,
)

print("Contract query result:", response.json())

.NET

query-method.cs

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var apiKey = Environment.GetEnvironmentVariable("FSCO_API_KEY");

        var client = new HttpClient();
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);

        var json = @"{
            ""methodName"": ""balanceOf"",
            ""paramCollection"": [""0xabc""],
            ""isShared"": false
        }";
        var content = new StringContent(json, Encoding.UTF8, "application/json");

        var response = await client.PostAsync("https://api.fsco.io/v2/contract/deployment/dep_abc123/query", content);
        var responseString = await response.Content.ReadAsStringAsync();

        Console.WriteLine("Contract query result: " + responseString);
    }
}

Response

JSON

response.json

{
  "query": {
    "deploymentId": "uuid",
    "methodName": "balanceOf",
    "paramCollection": ["0xabc"],
    "isShared": false
  },
  "response": {
    "balance": "1000000000000000000"
  }
}

Important Notes

• This request does not modify blockchain state
• This request does not require a wallet
• The query is executed on the latest block
• The response is returned immediately
• Make sure the method you’re calling is marked view or pure in the ABI
• This is ideal for checking balances, ownerOf, or any informational method

Next Steps

• Call a Contract Method
• Contract Module Overview
• Contract API Reference