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Mirror pipeline transforms can be used to decode raw contracts during processing using a combination of the _gs_fetch_abi and _gs_evm_decode functions

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Overview

To get decoded contract data on EVM chains in a Mirror pipeline, there are three options:

  1. Decode data with a subgraph, then use a subgraph entity source.
  2. Use the decoded_logs and decoded_traces direct indexing datasets. These are pre-decoded datasets, with coverage for common contracts, events, and functions.
  3. Use the raw_logs dataset and decode inside a pipeline transform.

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Decoding with transforms

Mirror provides custom functions for decoding.

This is full example definition which will define a pipeline that decodes friendtech events from raw logs.

sources:
  - type: dataset
    referenceName: base.raw_logs
    version: 1.0.0
transforms:
  - referenceName: friendtech_decoded
    type: sql
    primaryKey: id
    # Fetch the ABI from basescan, then use it to decode from the friendtech address.
    sql: >
      select 
        `id`,
        _gs_evm_decode(
            _gs_fetch_abi('https://api.basescan.org/api?module=contract&action=getabi&address=0xcf205808ed36593aa40a44f10c7f7c2f67d4a4d4', 'etherscan'), 
            `topics`, 
            `data`
        ) as `decoded`, 
        block_number, 
        transaction_hash 
      from base.raw_logs
      where address='0xcf205808ed36593aa40a44f10c7f7c2f67d4a4d4'
  - referenceName: friendtech_clean
    primaryKey: id
    type: sql
    # Clean up the previous transform, unnest the values from the `decoded` object.
    sql: >
      select 
        `id`, 
        decoded.event_params as `event_params`, 
        decoded.event_signature as `event_signature`,
        block_number,
        transaction_hash
      from friendtech_decoded 
      where decoded is not null
sinks:
  - referenceName: friendtech_events
    secretName: EXAMPLE_SECRET
    type: postgresql
    sourceStreamName: friendtech_clean
    schema: decoded_events
    table: friendtech

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_gs_evm_decode

_gs_evm_decode can decode data given a json string representing the ABI string.

It will automatically use the matching event in the ABI, but partial ABIs that only contain the target event will also work.

select _gs_evm_decode(abi, topics, data) as result
from ethereum.raw_log
where address = '0x...'

Using a WHERE clause on address or another topic is highly recommended the amount of resources needed by the pipeline

The function will output a nested ROW type with event_param::TEXT[] and event_signature::TEXT. If you’re planning on using a sink that doesn’t supported nested ROWs, you may want to do a further transformation to unnest the result.

If above transformation was named decoded_logs:

select result.event_params as event_params, result.event_signature as event_signature
from decoded_logs

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Parameters

abi
string

A string representing a json array of events and functions

topics
string

A string containing the topics, comma separated.

data
string

A string containing the payload of the event Example:

This function is stateless, and will scale very well across different pipeline sizes.

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_gs_fetch_abi

We provide a convenient function for fetching ABIs, as often they are too big to copy and paste into the yaml definition.

There is an option for fetching from etherscan-like sites, like bscscan, https://optimistic.etherscan.io/, or basescan.

It’s highly recommended to include your own etherscan API key if you are using this function with a large pipeline. The amount of workers may result in the API limits being surpassed.

select
    # Call the EVM decoding function
    _gs_evm_decode(
        # This fetches the ABI from basescan, a `etherscan` compatible site.
        _gs_fetch_abi('https://api.basescan.org/api?module=contract&action=getabi&address=0xcf205808ed36593aa40a44f10c7f7c2f67d4a4d4', 'etherscan'),
        `topics`,
        `data`
    ) as `decoded`,
from base.raw_logs

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Parameters

url
string

The URL from where the ABI will be fetched

type
string

The type of url - be either etherscan for etherscan-compatible APIs, or raw for json array ABIs.

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