Filter
getFilterChanges
Polling method for a filter, which returns an array of logs since the last poll.
Parameters
filterId
String
The filter id.
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
Promise returns Array - Array of log objects, or an empty array if nothing has changed since last poll.
The structure of the returned log Object in the Array looks as follows:
address
20-byte DATA
Address from which this log originated.
topics
Array of DATA
Array of 0 to 4 32-byte DATA of indexed log arguments. (In Solidity: The first topic is the hash of the signature of the event (e.g., Deposit(address,bytes32,uint256)), except you declared the event with the anonymous specifier.).
data
DATA
Contains the non-indexed arguments of the log.
blockNumber
QUANTITY
The block number where this log was in. null when pending.
transactionHash
32-byte DATA
Hash of the transaction that this log was created from. null when pending, an edge case when the transaction has been executed, but the block has not been confirmed.
transactionIndex
QUANTITY
Integer. The index of the transaction that this log was created from. null when pending.
blockHash
32-byte DATA
Hash of the block where this log was in. null when pending.
logIndex
QUANTITY
Integer of the log index position in the block. null when it is a pending log.
id
String
A log identifier. It is made by concatenating "log_" string with keccak256(blockHash + transactionHash + logIndex).substr(0, 8)
Example
getFilterLogs
Returns an array of all logs matching the filter with the given id. The filter object should be obtained using newFilter. Note that filter ids returned by other filter creation functions, such as newBlockFilter or newPendingTransactionFilter, cannot be used with this function.
Parameters
filterId
String
The filter id.
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
See getFilterChanges
Example
getPastLogs
Gets past logs, matching the given options.
Parameters
options
Object
The filter options.
options.fromBlock
Number | String
(optional) The number of the earliest block to get the logs. ("latest" means the most recent block.) The default value is "latest".
options.toBlock
Number | String
(optional) The number of the last block to get the logs. ("latest" means the most recent block.). The default value is "latest".
options.address
String | Array
(optional) An address or a list of addresses. Only the logs related to the particular account(s) will be returned.
options.topics
Array
(optional) An array of values that must appear in the log entries. The order is important. If you want to leave topics out, use null, e.g., [null, '0x12...']. You can also pass an array for each topic with options for that topic, e.g., [null, ['option1', 'option2']].
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
Promise returns Array - Array of log objects.
The structure of the returned event Object in the Array looks as follows:
address
String
From which this event originated from.
data
String
The data containing non-indexed log parameter.
topics
Array
An array with max 4 32-byte topics, topic 1-3 contains indexed parameters of the log.
logIndex
Number
Integer of the event index position in the block.
transactionIndex
Number
Integer of the transaction's index position, the event was created in.
transactionHash
32-byte String
Hash of the transaction this event was created in.
blockHash
32-byte String
Hash of the block where this event was created in. null when its still pending.
blockNumber
Number
The block number where this log was created in. null when still pending.
id
String
A log identifier. It is made through concatenating "log_" string with keccak256(blockHash + transactionHash + logIndex).substr(0, 8)
Example
newBlockFilter
Creates a filter in the node to receive the information about new block arrival. To check if the state has changed, call getFilterChanges.
Parameters
callback
Function
(optional) Optional callback. The callback is fired with an error object as its first parameter and the result as the second.
Return Value
Promise returns String - A filter id.
Example
newFilter
Creates a filter object using the given filter options, to receive the specific state changes (logs).
To check if the state has changed, call getFilterChanges.
To obtain all logs matching the filter created by
newFilter, call getFilterLogs.
For detailed information about topic filters, please see Klaytn Platform API - klay_newFilter.
Parameters
options
Object
The filter options.
options.fromBlock
Number | String
(optional) The number of the earliest block height to query the events. (There are special tags, "latest" means the most recent block). The default value is "latest".
options.toBlock
Number | String
(optional) The number of the last block height to query the events (There are special tags,"latest" means the most recent confirmed block). The default value is "latest".
options.address
String | Array
(optional) An address or a list of addresses to get logs generated inside the given contract(s).
options.topics
Array
(optional) An array of values to search for in the log entries. The order is important. If you want to match everything in the given position, use null, e.g., [null, '0x12...']. You can also pass an array to match one of them. e.g., [null, ['option1', 'option2']].
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
Promise returns String - A filter id.
Example
newPendingTransactionFilter
Creates a filter in the node, to receive the information about new pending transactions arrival. To check if the state has changed, call getFilterChanges.
Parameters
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
Promise returns String - A filter id.
Example
uninstallFilter
Removes the filter with the given id. It is strongly recommended to immediately remove the filter if monitoring is no longer needed. A filter will be removed if the filter has not been invoked through getFilterChanges for more than the timeout value set in the node. The default configuration is 5 minutes.
Parameters
filterId
String
The filter id.
callback
Function
(optional) Optional callback, returns an error object as the first parameter and the result as the second.
Return Value
Promise returns Boolean - true if the filter was successfully uninstalled, otherwise false.
Example
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