Introduction

Interacting with blockcahin is all about transactions. Web3 module has many useful transaction functions which we can use to get all the information about any trnasaction happened on the network. This smartbook will discuss about only get/retrieve/call methods. 

You can read this smartbook for all gas operations with web3.

Transaction Methods

Lets initialise web3 first 

const web3 = require('web3');

1. getTransaction

This method returns a transaction details about any provided transaction hash.

Syntax  :  web3.eth.getTransaction(transactionHash [, callback])

Parameters  :

• String  -  The transaction hash.
• Function  -  (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns  :

A transaction object is returned which contains following properties  :

• hash  -  [ 32 Bytes String ]  Hash of the transaction.
• nonce  -  [ Number ]  The number of transactions made by the sender prior to this one.
• blockHash 32 Bytes  -  [ String ]  Hash of the block where this transaction was in. null if pending.
• blockNumber  -  [ Number ]  Block number where this transaction was in. null if pending.
• transactionIndex  -  [ Number ]  Integer of the transactions index position in the block. null if pending.
• from  -  [ String ]  Address of the sender.
• to  -  [ String ]  Address of the receiver. null if it’s a contract creation transaction.
• value  -  [ String  ]  Value transferred in wei.
• gasPrice  -  [ String ]  Gas price provided by the sender in wei.
• gas  -  [ Number ]  Gas provided by the sender.
• input  -  [ String ]  The data sent along with the transaction.

Example  :

web3.eth.getTransaction(
'0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b§234'
).then(console.log);

Output  :

> {
    "hash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
    "nonce": 2,
    "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
    "blockNumber": 3,
    "transactionIndex": 0,
    "from": "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b",
    "to": "0x6295ee1b4f6dd65047762f924ecd367c17eabf8f",
    "value": '123450000000000000',
    "gas": 314159,
    "gasPrice": '2000000000000',
    "input": "0x57cb2fc4"
}

2. getTransactionReceipt

The receipt is available only for mined transactions i.e. confirmed transctions. Note that the receipt is not available for pending transactions and returns null.

Syntax  :  web3.eth.getTransactionReceipt(hash [, callback])

Parameters  :

• String  -  The transaction hash.
• Function  -  (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns  :

A transaction receipt object is returned with following properties :

• status  -  [ Boolean ]  TRUE if the transaction was successful, FALSE if the EVM reverted the transaction.
• blockHash  -  [ 32 Bytes  String ]  Hash of the block where this transaction was in.
• blockNumber  -  [ Number ]  Block number where this transaction was in.
• transactionHash -  [ 32 Bytes  String ]  Hash of the transaction.
• transactionIndex  -  [ Number ]  Integer of the transactions index position in the block.
• from  -  [ String ]  Address of the sender.
• to  -  [ String ]  Address of the receiver. null when it’s a contract creation transaction.
• contractAddress  -  [ String ]  The contract address created, if the transaction was a contract creation, otherwise null.
• cumulativeGasUsed  -  [ Number ]  The total amount of gas used when this transaction was executed in the block.
• gasUsed  -  [ Number ]  The amount of gas used by this specific transaction alone.
• logs  -  [ Array ]  Array of log objects, which this transaction generated.

Example  :

var receipt = web3.eth.getTransactionReceipt(
'0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b
').then(console.log);

Output  :

> {
  "status": true,
  "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
  "transactionIndex": 0,
  "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
  "blockNumber": 3,
  "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
  "cumulativeGasUsed": 314159,
  "gasUsed": 30234,
  "logs": [{
         // logs as returned by getPastLogs, etc.
     }, ...]

3. getTransactionFromBlock

It returns a transaction based on a block hash or number and the transaction’s index position.

Syntax  :  getTransactionFromBlock(hashStringOrNumber, indexNumber [, callback])

Parameters  :

• String, Number, BN, BigNumber  -  A block number or hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
• Number  -  The transaction’s index position.
• Function (optional)  -  Optional callback, returns an error object as first parameter and the result as second.

Returns  :  A transaction object same as getTransaction method containing following properties  

• hash  -  [ 32 Bytes String ]  Hash of the transaction.
• nonce  -  [ Number ]  The number of transactions made by the sender prior to this one.
• blockHash 32 Bytes  -  [ String ]  Hash of the block where this transaction was in. null if pending.
• blockNumber  -  [ Number ]  Block number where this transaction was in. null if pending.
• transactionIndex  -  [ Number ]  Integer of the transactions index position in the block. null if pending.
• from  -  [ String ]  Address of the sender.
• to  -  [ String ]  Address of the receiver. null if it’s a contract creation transaction.
• value  -  [ String  ]  Value transferred in wei.
• gasPrice  -  [ String ]  Gas price provided by the sender in wei.
• gas  -  [ Number ]  Gas provided by the sender.
• input  -  [ String ]  The data sent along with the transaction.

Example  :

var transaction = web3.eth.getTransactionFromBlock('0x4534534534', 2).then(console.log);

Output  :

> {
    "hash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
    "nonce": 2,
    "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
    "blockNumber": 3,
    "transactionIndex": 0,
    "from": "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b",
    "to": "0x6295ee1b4f6dd65047762f924ecd367c17eabf8f",
    "value": '123450000000000000',
    "gas": 314159,
    "gasPrice": '2000000000000',
    "input": "0x57cb2fc4"
}

4. getPendingTransactions

Returns a list of pending transactions of provided account.

Syntax  :  web3.eth.getPendingTransactions([, callback])

Parameters  :

• Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns  :  It returns Array of pending transactions with following properties  :

• hash  -  [ 32 Bytes String ]  Hash of the transaction.
• nonce  -  [ Number ]  The number of transactions made by the sender prior to this one.
• blockHash 32 Bytes  -  [ String ]  Hash of the block where this transaction was in. null if pending.
• blockNumber  -  [ Number ]  Block number where this transaction was in. null if pending.
• transactionIndex  -  [ Number ]  Integer of the transactions index position in the block. null if pending.
• from  -  [ String ]  Address of the sender.
• to  -  [ String ]  Address of the receiver. null if it’s a contract creation transaction.
• value  -  [ String  ]  Value transferred in wei.
• gasPrice  -  [ String ]  Gas price provided by the sender in wei.
• gas  -  [ Number ]  Gas provided by the sender.
• input  -  [ String ]  The data sent along with the transaction.

Example  :

web3.eth.getPendingTransactions().then(console.log);

Output  :

 >  [
     {
         hash: '0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b',
         nonce: 2,
         blockHash: '0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46',
         blockNumber: 3,
         transactionIndex: 0,
         from: '0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b',
         to: '0x6295ee1b4f6dd65047762f924ecd367c17eabf8f',
         value: '123450000000000000',
         gas: 314159,
         gasPrice: '2000000000000',
         input: '0x57cb2fc4'
         v: '0x3d',
         r: '0xaabc9ddafffb2ae0bac4107697547d22d9383667d9e97f5409dd6881ce08f13f',
         s: '0x69e43116be8f842dcd4a0b2f760043737a59534430b762317db21d9ac8c5034'
     },....,{
         hash: '0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b',
         nonce: 3,
         blockHash: '0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46',
         blockNumber: 4,
         transactionIndex: 0,
         from: '0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b',
         to: '0x6295ee1b4f6dd65047762f924ecd367c17eabf8f',
         value: '123450000000000000',
         gas: 314159,
         gasPrice: '2000000000000',
         input: '0x57cb2fc4'
         v: '0x3d',
         r: '0xaabc9ddafffb2ae0bac4107697547d22d9383667d9e97f5409dd6881ce08f13f',
         s: '0x69e43116be8f842dcd4a0b2f760043737a59534430b762317db21d9ac8c5034'
     }
]

5. getTransactionCount

Get the number of transactions sent from this address. This function can also help us get nonce as well.

Syntax  :  web3.eth.getTransactionCount(address [, defaultBlock] [, callback])

Parameters  :

• String - The address to get the numbers of transactions from.
• Number, String, BN, BigNumber - (optional) If you pass this parameter it will not use the default block set with web3.eth.defaultBlock. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
• Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns  :  It returns the number of transactions sent from the given address.

Example  :

web3.eth.getTransactionCount(
"0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe"
).then(console.log);

Output  :

> 1

So these are transaction retrieval methods which web3 provides. We can also extend our web3 module as well, you can check how to extend it in this smartbook.