make-software/ces-go-parser

The Golang library for parsing Casper Event Standard events

CES Go Parser

ces-go-parser parses contract-level events that follow the Casper Event Standard.

The library is built on top of the casper-go-sdk and operates on types defined by the SDK.

Install

go get github.com/make-software/ces-go-parser

Usage

Here is an example of parsing CES events using ces-go-parser from a real Testnet deploy loaded with casper-go-sdk:

package main

import (
	"context"
	"fmt"
	"net/http"

	"github.com/make-software/casper-go-sdk/casper"

	"github.com/make-software/ces-go-parser"
)

func main() {
	testnetNodeAddress := "<put testnet node address here>"
	rpcClient := casper.NewRPCClient(casper.NewRPCHandler(testnetNodeAddress, http.DefaultClient))

	ctx := context.Background()
	deployResult, err := rpcClient.GetDeploy(ctx, "c1bb9ae27877f5ecf4ef71307e7ee3c403bcace065565c3645b81ec0a9bc8978")
	if err != nil {
		panic(err)
	}

	contractHash, err := casper.NewHash("0640eb43bd95d5c88b799862bc9fb42d7a241f1a8aae5deaa03170a27ee8eeaa")
	if err != nil {
		panic(err)
	}

	parser, err := ces.NewParser(rpcClient, []casper.Hash{contractHash})
	if err != nil {
		panic(err)
	}

	parseResults, err := parser.ParseExecutionResults(deployResult.ExecutionResults[0].Result)
	if err != nil {
		panic(err)
	}
	for _, result := range parseResults {
		if result.Error != nil {
			panic(err)
		}
		fmt.Println(result.Event)
	}
}

API

Go CES Parser provides several public types and functions:

• Parser
  • NewParser
  • Parser.ParseExecutionResults
  • Parser.FetchContractSchemasBytes
• NewSchemasFromBytes
• EventData
• Event
  • ParseEventNameAndData
• ParseResult
• Schemas
• SchemaData

Parser

Parser that accepts a list of observed contracts and provides possibility to parse CES events out of deploy execution results

NewParser

NewParser constructor that accepts casper-go-sdk client:

Argument	Type	Description
casperRPCClient	casper.RPCClient	Instance of the casper-go-sdk RPC client
contracts	[]casper.Hash	List of the observed contract hashes

Example

package main

import (
	"net/http"

	"github.com/make-software/casper-go-sdk/casper"

	"github.com/make-software/ces-go-parser"
)

func main() {
	rpcClient := casper.NewRPCClient(casper.NewRPCHandler("http://localhost:11101/rpc", http.DefaultClient))
	contractHash, err := casper.NewHash("e7062b42c9a22002fa3cd216debd605b7056ad180efb3c99555676f1a1e801e5")
	if err != nil {
		panic(err)
	}

	parser, err := ces.NewParser(rpcClient, []casper.Hash{contractHash})
	if err != nil {
		panic(err)
	}
	_ = parser
}

ParseExecutionResults

ParseExecutionResults method that accepts deploy execution results and returns []ces.ParseResult:

Argument	Type	Description
executionResults	casper.ExecutionResults	Deploy execution results provided as the corresponding type from casper-go-sdk

FetchContractSchemasBytes

FetchContractSchemasBytes method that accepts contract hash and return bytes representation of stored schema:

Argument	Type	Description
contractHash	casper.Hash	Contract hash schema want to be fetched

NewSchemasFromBytes

NewSchemasFromBytes constructor that accepts raw CES schema bytes stored under the contract __events_schema URef and returns ces.Schemas:

Argument	Type	Description
rawSchemas	[]byte	Raw contract schemas bytes

ParseEventNameAndData

Function that accepts raw event bytes and contract event schemas and returns ParseResult:

Argument	Type	Description
event	string	Raw event bytes in hex
schemas	ces.Schemas	The list of contract schemas

Example

schemas, err := ces.NewSchemasFromBytes(rawSchemas)
rawEvent  := BytesFromString("some real example here")

eventData, err := ces.ParseEvent(rawEvent, schemas)

EventData

Value-object that represents an event data:

Property	Type	Description
Name	string	Event name
Data	map[string]casper.CLValue	Event Data

Event

Value-object that represents an event:

Property	Type	Description
Name	string	Event Name
EventData	ces.EventData	EventData
ContractHash	casper.Hash	Event ContractHash
ContractPackageHash	casper.Hash	Event ContractPackageHash
TransformID	uint	Event TransformID
EventID	uint	EventID

ParseResult

Value-object that represents a parse result. Contains error representing weather parsing was successful or not.

Property	Type	Description
Error	error	Parse result error
Event	ces.Event	ces Event

SchemaData

SchemaData is - value-object that represents an schema item.

Property	Type	Description
ParamName	string	Name of the param
ParamType	casper.CLType	casper CLType

Schemas

Schemas represent a map of event name and list of SchemaData.

Tests

To run unit tests for the library, make sure you are in the root of the library:

go test ./...