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Filter

klay_getFilterChanges

Polling method for a filter, which returns an array of logs which occurred since last poll.

Parameters

Name
Type
Description

QUANTITY

string

The filter id (e.g., "0x16" // 22).

Return Value

Array - Array of log objects, or an empty array if nothing has changed since last poll.

  • For filters created with klay_newBlockFilter, the return are block hashes (32-byte DATA), e.g., ["0x3454645634534..."].

  • For filters created with klay_newPendingTransactionFilter, the return are transaction hashes (32-byte DATA), e.g., ["0x6345343454645..."].

  • For filters created with klay_newFilter, logs are objects with following parameters:

Name
Type
Description

removed

TAG

true when the log was removed, due to a chain reorganization. false if it is a valid log.

logIndex

QUANTITY

Integer of the log index position in the block. null when it is a pending log.

transactionIndex

QUANTITY

Integer of the transactions index position log was created from. null when pending.

transactionHash

32-byte DATA

Hash of the transactions this log was created from. null when pending.

blockHash

32-byte DATA

Hash of the block where this log was in. null when pending.

blockNumber

QUANTITY

The block number where this log was in. null when pending.

address

20-byte DATA

Address from which this log originated.

data

DATA

Contains the non-indexed arguments of the log.

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.).

Example

// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_getFilterChanges","params":["0x16"],"id":73}' https://public-en-baobab.klaytn.net

// Result
{
    "id":1,
    "jsonrpc":"2.0",
    "result": [{
    "logIndex": "0x1", // 1
    "blockNumber":"0x1b4", // 436
    "blockHash": "0x8216c5785ac562ff41e2dcfdf5785ac562ff41e2dcfdf829c5a142f1fccd7d",
    "transactionHash":  "0xdf829c5a142f1fccd7d8216c5785ac562ff41e2dcfdf5785ac562ff41e2dcf",
    "transactionIndex": "0x0", // 0
    "address": "0x16c5785ac562ff41e2dcfdf829c5a142f1fccd7d",
    "data":"0x0000000000000000000000000000000000000000000000000000000000000000",
    "topics": ["0x59ebeb90bc63057b6515673c3ecf9438e5058bca0f92585014eced636878c9a5"]
    },{
        ...
    }]
}

klay_getFilterLogs

Returns an array of all logs matching filter with given id, which has been obtained using klay_newFilter. Note that filter ids returned by other filter creation functions, such as klay_newBlockFilter or klay_newPendingTransactionFilter, cannot be used with this function.

The execution of this API can be limited by two node configurations to manage resources of Klaytn node safely.

  • The number of maximum returned results in a single query (Default: 10,000).

  • The execution duration limit of a single query (Default: 10 seconds).

Parameters

Name
Type
Description

QUANTITY

string

The filter id

Return Value

See klay_getFilterChanges

Example

// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_getFilterLogs","params":["0xd32fd16b6906e67f6e2b65dcf48fc272"],"id":1}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc":"2.0",
  "id":1,
  "result":[{
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xd596fdad182d29130ce218f4c1590c4b5ede105bee36690727baa6592bd2bfc8"],
      "data":"0x0000000000000000000000000000000000000000000000000000000000000064000000000000000000000000000000000000000000000000000000000000007b",
      "blockNumber":"0x54",
      "transactionHash":"0xcd4703cd62bd930d4652999bce8dcb75b7ade49d922fa42dc11e568c52a5fa6f",
      "transactionIndex":"0x0",
      "blockHash":"0x9a49f30f1d1876ff3913bd0aa58f328822e7a369cb13e0640b82234f26e781bb",
      "logIndex":"0x0",
      "removed":false
  }]
}

klay_getLogs

Returns an array of all logs matching a given filter object.

The execution of this API can be limited by two node configurations to manage resources of Klaytn node safely.

  • The number of maximum returned results in a single query (Default: 10,000).

  • The execution duration limit of a single query (Default: 10 seconds).

Parameters

Object - The filter options:

Name
Type
Description

fromBlock

QUANTITY | TAG

(optional, default: "latest") Integer or hexadecimal block number, or the string "earliest", "latest" or "pending" as in the default block parameter.

toBlock

QUANTITY | TAG

(optional, default: "latest") Integer or hexadecimal block number, or the string "earliest", "latest" or "pending" as in the default block parameter.

address

20-byte DATA | Array

(optional) Contract address or a list of addresses from which logs should originate.

topics

Array of DATA

(optional) Array of 32-byte DATA topics. Topics are order-dependent. Each topic can also be an array of DATA with “or” options.

blockHash

32-byte DATA

(optional) A filter option that restricts the logs returned to the single block with the 32-byte hash blockHash. Using blockHash is equivalent to fromBlock = toBlock = the block number with hash blockHash. If blockHash is present in in the filter criteria, then neither fromBlock nor toBlock are allowed.

NOTE: In versions earlier than Klaytn v1.7.0, only integer block number, the string "earliest" and "latest" are available.

Return Value

See klay_getFilterChanges

Examples

// Request
$ curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_getLogs","params":[{"fromBlock":"0x1","toBlock":"latest","address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b"}],"id":1}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc":"2.0",
  "id":1,
  "result":[
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xfa9b2165fc71c1d6ffa03291c7f5d223ea363ec063d747eec9ce2d30d24855ef"],
      "data":"0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000060000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b481000000000000000000000000000000000000000000000000000000000000001341646472657373426f6f6b436f6e747261637400000000000000000000000000",
      "blockNumber":"0xd3b5",
      "transactionHash":"0x57ca8ff0a0d454d4c5418694c21bc4ef3de26cf7cd18dd404d6a7189a826bfe0",
      "transactionIndex":"0x0",
      "blockHash":"0x279251a907c6ab1fb723595511ff401432e7c2437d54189298f53a7d33ce3a60",
      "logIndex":"0x0",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xfa3e1e272694072320aad73a3fadd8876c4bf8f40899c6c7ce2fda9f4e652cfa"],
      "data":"0x00000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000003000000000000000000000000000000000000000000000000000000000000000300000000000000000000000041383b6ee0ea5108d6b139165a9c85351aacd39800000000000000000000000057f7439898e652fa9b5654022297588532e5e0370000000000000000000000005b5b7a718a4124eb746ae00b1ce6edcaa5ab55bc",
      "blockNumber":"0xd3b5",
      "transactionHash":"0x57ca8ff0a0d454d4c5418694c21bc4ef3de26cf7cd18dd404d6a7189a826bfe0",
      "transactionIndex":"0x0",
      "blockHash":"0x279251a907c6ab1fb723595511ff401432e7c2437d54189298f53a7d33ce3a60",
      "logIndex":"0x1",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b481000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000003000000000000000000000000286d09b578d6126e09296dfe6c775ea7d0cf06e9000000000000000000000000860350f6d774efd16046335c388b832b910d3f8c00000000000000000000000061a7cbdd597848494fa85cbb76f9c63ad9c06cad",
      "blockNumber":"0x14d96",
      "transactionHash":"0x73282602d2f908180f47e3c8673f41c0899cbbb2d606976c2f77188ffa57d6e7",
      "transactionIndex":"0x0",
      "blockHash":"0xa5268a093cd5df7eccde18217a7019a35ab761088312027af16682aafa704ee3",
      "logIndex":"0x1",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b4810000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000000030000000000000000000000002f91d1b79dd06da1b622122d61e05e64562de61e0000000000000000000000006e76e0ce76dfba55060400144318d4821a58510600000000000000000000000031b93ca83b5ad17582e886c400667c6f698b8ccd",
      "blockNumber":"0x14e4e",
      "transactionHash":"0xf9d86ed451d67abc68c517f7fa0e0a7a8e3dedec23f56febda2b7f52d35185b6",
      "transactionIndex":"0x0",
      "blockHash":"0x7ddf4a0a203d40afc1706aa24b787da601e1bce326319349d0eeef6c41656fa5",
      "logIndex":"0x1",
      "removed":false
    }
  ]
}
// Request
$ curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_getLogs","params":[{"fromBlock":"earliest","toBlock":"latest","topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"]}],"id":2}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc":"2.0",
  "id":2,
  "result":[
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b481000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000003000000000000000000000000286d09b578d6126e09296dfe6c775ea7d0cf06e9000000000000000000000000860350f6d774efd16046335c388b832b910d3f8c00000000000000000000000061a7cbdd597848494fa85cbb76f9c63ad9c06cad",
      "blockNumber":"0x14d96",
      "transactionHash":"0x73282602d2f908180f47e3c8673f41c0899cbbb2d606976c2f77188ffa57d6e7",
      "transactionIndex":"0x0",
      "blockHash":"0xa5268a093cd5df7eccde18217a7019a35ab761088312027af16682aafa704ee3",
      "logIndex":"0x1",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b4810000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000000030000000000000000000000002f91d1b79dd06da1b622122d61e05e64562de61e0000000000000000000000006e76e0ce76dfba55060400144318d4821a58510600000000000000000000000031b93ca83b5ad17582e886c400667c6f698b8ccd",
      "blockNumber":"0x14e4e",
      "transactionHash":"0xf9d86ed451d67abc68c517f7fa0e0a7a8e3dedec23f56febda2b7f52d35185b6",
      "transactionIndex":"0x0",
      "blockHash":"0x7ddf4a0a203d40afc1706aa24b787da601e1bce326319349d0eeef6c41656fa5",
      "logIndex":"0x1",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b481000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000003000000000000000000000000a2b1264624c92257dd8e7f0cac42d451061d1510000000000000000000000000b381ee81e319e5ec48f42d0b47b5e4361c9a6f740000000000000000000000003855407fa65c4c5104648b3a9e495072df62b585",
      "blockNumber":"0x14f38",
      "transactionHash":"0xc8f8c637ea9fcbe71e23fe0779b59fb10173e8c4fd7e49bce3cce76ff67d353d",
      "transactionIndex":"0x0",
      "blockHash":"0xb1717038e443f517bd7a8c37b66fb731fed573f5fa5486ebbbb5e4c9060be50b",
      "logIndex":"0x1",
      "removed":false
    },
    {
      "address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b",
      "topics":["0xc7b359b1e189b7d721be7f0765a8d745be718566b8e67cbd2728dae5d6fd64b6"],
      "data":"0x000000000000000000000000d3564e57bb5c6f4d983a493a946534f8e1e8b4810000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000000030000000000000000000000009dd579f23912665b956b0cd50387b29a62052732000000000000000000000000c98a86af2eca2989c0cb2a2b8d4bb841f11e94ab000000000000000000000000f65e07b6626ab43ecea744803fa46bd4a89bfdb6",
      "blockNumber":"0x14fe7",
      "transactionHash":"0x14da1883bb2aae487ce1cb93cd39bc9bb802adbba083f337051877358150ab3f",
      "transactionIndex":"0x0",
      "blockHash":"0xcd820189f00e9a6faaea7313437b92114e69bd32e18b4a28e7763117716c6fa9",
      "logIndex":"0x1",
      "removed":false
    }
  ]
}

klay_newBlockFilter

Creates a filter in the node, to notify when a new block arrives. To check if the state has changed, call klay_getFilterChanges.

Parameters

None

Return Value

Type
Description

QUANTITY

A filter id.

Example

// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_newBlockFilter","params":[],"id":73}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc":"2.0",
  "id":73,
  "result":"0xc2f2e8168a7e38b5d979d0f7084130ee"
}

klay_newFilter

Creates a filter object, based on filter options, to notify when the state changes (logs).

A note on specifying topic filters: Topics are order-dependent. A transaction with a log with topics [A, B] will be matched by the following topic filters:

  • [] "anything"

  • [A] "A in first position (and anything after)"

  • [null, B] "anything in first position AND B in second position (and anything after)"

  • [A, B] "A in first position AND B in second position (and anything after)"

  • [[A, B], [A, B]] "(A OR B) in first position AND (A OR B) in second position (and anything after)"

Parameters

Object - The filter options:

Name
Type
Description

fromBlock

QUANTITY | TAG

(optional, default: "latest") Integer or hexadecimal block number, or the string "earliest", "latest" or "pending" as in the default block parameter.

toBlock

QUANTITY | TAG

(optional, default: "latest") Integer or hexadecimal block number, or the string "earliest", "latest" or "pending" as in the default block parameter.

address

20-byte DATA | Array

(optional) Contract address or a list of addresses from which logs should originate.

topics

Array of DATA

(optional) Array of 32-byte DATA topics. Topics are order-dependent. Each topic can also be an array of DATA with "or" options.

NOTE: In versions earlier than Klaytn v1.7.0, only integer block number, the string "earliest" and "latest" are available.

Return Value

Type
Description

QUANTITY

A filter id

Example

// Request
$ curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_newFilter","params":[{"fromBlock":"earliest","toBlock":"latest","address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b","topics":["0xd596fdad182d29130ce218f4c1590c4b5ede105bee36690727baa6592bd2bfc8"]}],"id":1}' https://public-en-baobab.klaytn.net

// Result
{"jsonrpc":"2.0","id":1,"result":"0xd32fd16b6906e67f6e2b65dcf48fc272"}

klay_newPendingTransactionFilter

Creates a filter in the node, to notify when new pending transactions arrive. To check if the state has changed, call klay_getFilterChanges.

Parameters

None

Return Value

Type
Description

QUANTITY

A filter id.

Example

// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_newPendingTransactionFilter","params":[],"id":73}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc":"2.0",
  "id":73,
  "result":"0x90cec22a723fcc725fb2462733c2880f"
}

klay_subscribe

Creates a new subscription to specific events by using either RPC Pub/Sub over WebSockets or filters over HTTP. It allows clients to wait for events instead of polling for them.

The node will return a subscription id for each subscription created. For each event that matches the subscription, a notification with relevant data is sent together with the subscription id. If a connection is closed, all subscriptions created over the connection are removed.

Parameters

Object - A notification type: "newHeads" or "logs".

"newHeads" notifies you of each block added to the blockchain. "logs" notifies you of logs included in new blocks. This type requires a second parameter that specifies filter options. For more details, go to klay_newFilter > parameters.

Return Value

Type
Description

QUANTITY

A subscription id when a subscription is created. For each event that matches the subscription, a notification with relevant data will be delivered as well.

Example

This API is appropriate for use with a WebSocket tool, wscat.

// Request
wscat -c http://localhost:8552
> {"jsonrpc":"2.0", "id": 1, "method": "klay_subscribe", "params": ["newHeads"]}

// Result
< {"jsonrpc":"2.0","id":1,"result":"0x48bb6cb35d6ccab6eb2b4799f794c312"}
< {"jsonrpc":"2.0","method":"klay_subscription","params":{"subscription":"0x48bb6cb35d6ccab6eb2b4799f794c312","result":{"parentHash":"0xc39755b6ac01d1e8c58b1088e416204f7af5b6b66bfb4f474523292acbaa7d57","reward":"0x2b2a7a1d29a203f60e0a964fc64231265a49cd97","stateRoot":"0x12aa1d3ab0440d844c28fbc6f89d26082f39a8435b512fa487ff55c2056aceb3","number":"0x303bea4”, ... ... }}}
// Request
wscat -c http://localhost:8552
> {"jsonrpc":"2.0", "id": 1, "method": "klay_subscribe", "params": ["logs", {"fromBlock":"earliest","toBlock":"latest","address":"0x87ac99835e67168d4f9a40580f8f5c33550ba88b","topics":["0xd596fdad182d29130ce218f4c1590c4b5ede105bee36690727baa6592bd2bfc8"]}]}

// Result
< {"jsonrpc":"2.0","id":1,"result":"0xbdab16c8e4ae1b9e6930c78359de3e0e"}
< {"jsonrpc":"2.0","method":"klay_subscription","params":{"subscription":"0xbdab16c8e4ae1b9e6930c78359de3e0e","result":{"address":"0x2e4bb340e26caffb4073d7f1151f37d17524cdbc","topics":["0xb1a7310b1a46c788fcf30784cad70442d5232acaef480b0c094c76bee8d9c77d"],"data":"0x0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000d2588fe96a34c56a5d0a484cb603bc16fc5cdbbc","blockNumber":"0x3041201","transactionHash":"0xdacdebc77006fc566f65448524a0bc770056d8c7a05244bc7bfb2123b1bd398c","transactionIndex":"0x0","blockHash":"0x899b2dbfe96a34ce5d965dbcfcf39d072b4ce1097d479923e6b6355f3e2609ec","logIndex":"0x0","removed":false}}}

klay_uninstallFilter

Uninstalls a filter with given id. Should always be called when watch is no longer needed. Additionally, filters timeout when they are not requested with klay_getFilterChanges for a period of time.

Parameters

Name
Type
Description

filter

QUANTITY

A filter id.

Return Value

Type
Description

Boolean

true if the filter was successfully uninstalled, otherwise false.

Example

// Request
curl -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"klay_uninstallFilter","params":["0xb"],"id":73}' https://public-en-baobab.klaytn.net

// Result
{
  "jsonrpc": "2.0",
  "id":1,
  "result": true
}

klay_unsubscribe

Cancels the subscription with a specific subscription id by using either RPC Pub/Sub over WebSockets or filters over HTTP. Only the connection that created a subscription can unsubscribe from it.

Parameters

Type
Description

QUANTITY

A subscription id.

Return Value

Type
Description

Boolean

true if the subscription was successfully canceled, otherwise false.

Example

This API is appropriate for use with a WebSocket tool, wscat.

// Request
> {"jsonrpc":"2.0", "id": 1, "method": "klay_unsubscribe", "params": ["0xab8ac7a4045025d0c2807d63060eea6d"]}

// Result
< {"jsonrpc":"2.0","id":1,"result":true}
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