Access Logs

Accessing logs using the KalyChain API

Subscribe to events, such as logs, using either RPC Pub/Sub over WebSockets or filters over HTTP.

Access logs using the following KalyChain API methods:

Use eth_newFilter to create the filter before using eth_getFilterChanges and eth_getFilterLogs).

The following examples use the sample contract included in [events and logs](../../concepts/events-and-logs.md).

Create a filter

Create a filter using eth_newFilter.

!!! example

If the [example contract](../../concepts/events-and-logs.md) was deployed to
0x42699a7612a82f1d9c36148af9c77354759b210b, the following request for `eth_newFilter` creates a
filter to log when `valueIndexed` is set to 5:

```json
{
  "jsonrpc":"2.0",
  "method":"eth_newFilter",
  "params":[
    {
      "fromBlock":"earliest",
      "toBlock":"latest",
      "address":"0x42699a7612a82f1d9c36148af9c77354759b210b",
      "topics":[
        ["0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8"],
        ["0x0000000000000000000000000000000000000000000000000000000000000005"]
      ]
    }
  ],
  "id":1
}
```

eth_newFilter returns a filter ID hash (for example, 0x1ddf0c00989044e9b41cc0ae40272df3).

Poll a filter for changes

To poll the filter for changes since the last poll, use eth_getFilterChanges with the filter ID hash returned by eth_newFilter.

!!! example

If the contract had been executed twice since the last poll, with `valueIndexed` set to 1 and
5, [`eth_getFilterChanges`](../../reference/api/index.md#eth_getfilterchanges) returns
only the log where the [topic](../../concepts/events-and-logs.md#event-parameters) for
`valueIndexed` is 5:

```json
{
    "jsonrpc": "2.0",
    "id": 1,
    "result": [
        {
            "logIndex": "0x0",
            "removed": false,
            "blockNumber": "0x21c",
            "blockHash": "0xc7e6c9d5b9f522b2c9d2991546be0a8737e587beb6628c056f3c327a44b45132",
            "transactionHash": "0xfd1a40f9fbf89c97b4545ec9db774c85e51dd8a3545f969418a22f9cb79417c5",
            "transactionIndex": "0x0",
            "address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
            "data": "0x0000000000000000000000000000000000000000000000000000000000000005",
            "topics": [
                "0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
                "0x0000000000000000000000000000000000000000000000000000000000000005"
            ]
        }
    ]
}
```

Get all logs for a filter

To get all logs for a filter, use eth_getFilterLogs.

!!! example

If the contract had been executed twice with `valueIndexed` set to 5 since the filter was
created using `eth_newFilter`, `eth_getFilterLogs` returns:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": [
    {
      "logIndex": "0x0",
      "removed": false,
      "blockNumber": "0x1a7",
      "blockHash": "0x4edda22a242ddc7bc51e2b6b11e63cd67be1af7389470cdea9c869768ff75d42",
      "transactionHash": "0x9535bf8830a72ca7d0020df0b547adc4d0ecc4321b7d5b5d6beb1eccee5c0afa",
      "transactionIndex": "0x0",
      "address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
      "data": "0x0000000000000000000000000000000000000000000000000000000000000005",
      "topics": [
        "0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
        "0x0000000000000000000000000000000000000000000000000000000000000005"
      ]
    },
    {
      "logIndex": "0x0",
      "removed": false,
      "blockNumber": "0x21c",
      "blockHash": "0xc7e6c9d5b9f522b2c9d2991546be0a8737e587beb6628c056f3c327a44b45132",
      "transactionHash": "0xfd1a40f9fbf89c97b4545ec9db774c85e51dd8a3545f969418a22f9cb79417c5",
      "transactionIndex": "0x0",
      "address": "0x42699a7612a82f1d9c36148af9c77354759b210b",
      "data": "0x0000000000000000000000000000000000000000000000000000000000000005",
      "topics": [
        "0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8",
        "0x0000000000000000000000000000000000000000000000000000000000000005"
      ]
    }
  ]
}
```


You can use [`eth_getLogs`](#get-logs-using-a-filter-options-object) with a filter options
object to get all logs matching the filter options instead of using
[`eth_newFilter`](../../reference/api/index.md#eth_newfilter) followed by
[`eth_getFilterLogs`](../../reference/api/index.md#eth_getfilterlogs).

Uninstall a filter

When a filter is no longer required, use eth_uninstallFilter to remove the filter.

Filters for private contracts

Filters for private contracts are created, accessed, and uninstalled using:

Get logs using a filter options object

To get all logs for a filter options object, use eth_getLogs or priv_getLogs for a private contract.

!!! example

The following request for `eth_getLogs` returns all the logs where the example contract has
been deployed to `0x42699a7612a82f1d9c36148af9c77354759b210b` and executed with `valueIndexed`
set to 5.

```json
{
  "jsonrpc":"2.0",
  "method":"eth_getLogs",
  "params":[
    {
      "fromBlock":"earliest",
      "toBlock":"latest",
      "address":"0x42699a7612a82f1d9c36148af9c77354759b210b",
      "topics":[
        ["0xd3610b1c54575b7f4f0dc03d210b8ac55624ae007679b7a928a4f25a709331a8"],
        ["0x0000000000000000000000000000000000000000000000000000000000000005"]
      ]
      }
  ],
  "id":1
}
```

The above example returns the same result as calling [eth_newFilter](#creating-a-filter)
followed by [eth_getFilterLogs](#getting-all-logs-for-a-filter).
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