Here is the sample code:

 function myFunc(string name) public returns(bool,bytes32)
    bytes32 hash= sha256(name);
    names[hash] = true; 
    return (true,hash);

Here names is mapping, I am trying to store names in blockchain. I have returned (true,hash), but when I call the function from frontend i receive the transaction hash. How can I get what i want to return?

2 Answers 2


This is a "facts of life" thing.

You can return(bool success) and this will be visible to other contracts that call the function, e.g. in a chain of functions calling functions in other contracts.

Transactions always start with an externally owned account signing a transaction and submitting it to the network. The returned value is a transaction receipt. The outcome of the transaction is unknown because nothing has happened yet except that a request has been submitted to the network for verification in the future.

A typical approach to coping with this fact of life is to wait for the transaction to be mined, then inspect the transaction log for useful output, inspect the success/fail status and draw your own conclusions, or inspect a read-only function to discover the new state after the transaction was mined. The returned values are forever out of reach for a Web3 client.

Hope it helps.

  • So there is no way to implement what I want my contract to do, is that what you're saying? And it will always return transaction hash when i use web3? Dec 24, 2017 at 15:54
  • if the function changes state of the contract then you will get transaction hash. if it is not changing the state then you can return any parameter. Dec 25, 2018 at 7:58

Rob Hitches has explained it really well. But if you want return values, then you can use events. you can emit an event and add a listener in your app.

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