Build a NEAR dApp · 2 min read

Calling Contract Methods

Choose gas and deposit correctly, pass arguments that match the ABI, handle failures, and refresh state with a view call after a change call.

Once you can connect a wallet and make a view call, the remaining job is to call the right method with the right arguments, gas, and deposit.

Views, again, with near-api-js

import { JsonRpcProvider } from "near-api-js";
 
const provider = new JsonRpcProvider({ url: "https://test.rpc.fastnear.com" });
 
const diploma = await provider.callFunction({
  contractId: "diploma.retr0school.testnet",
  method: "verify_diploma",
  args: { account_id: "demo-learner.retr0school.testnet", track: "near" },
});

If you cannot use the library (for example in the Playground), a raw fetch to https://rpc.testnet.fastnear.com with request_type: "call_function" and args_base64 is the same RPC.

Change calls with NEAR Connect

const wallet = await connector.wallet();
 
const result = await wallet.signAndSendTransaction({
  receiverId: "hello.near-examples.testnet",
  actions: [
    {
      type: "FunctionCall",
      params: {
        methodName: "set_greeting",
        args: { greeting: "Hello from Retr0 Academy" },
        gas: "30000000000000", // 30 Tgas
        deposit: "0",
      },
    },
  ],
});

Rules of thumb:

Gas is a string of gas units. 30 Tgas (30 + 12 zeros) is enough for a simple call. Cross-contract work often needs 50–100 Tgas or more, and the contract may attach static gas to promises.
Deposit is a string of yoctoNEAR. "0" for non-payable methods. "10000000000000000000000" is 0.01 NEAR. Payable methods (#[payable] in Rust) will panic if you attach nothing when they require a deposit.
Args must match the ABI. A typo in a field name is a failed transaction, not a compiler error, when you call from JS.
Wait for the transaction, then re-read state with a view call. Do not trust the wallet UI alone.

Errors you will see

Symptom	Likely cause
`MethodNotFound`	Wrong name or you deployed a different Wasm
`Must attach X yoctoNEAR`	Payable method or 1-yocto safety check
`Exceeded the prepaid gas`	Raise gas, or the contract's promises need a bigger budget
Wallet closed / rejected	The user cancelled; offer to try again

The next lesson puts a view call, a result panel, and optional signed calls together as a mini project.

Exercise

Write a signAndSendTransaction call to a payable method that attaches 0.01 NEAR and 30 Tgas. Then write the view call you would run afterwards to confirm the state change.

Open in Playground

Saved in this browser.

Connect a Wallet Mini Project: Diploma Checker