retriever for generating list of all token holder addresses + updated transformer to use said addresses to populate balanceOf and allowance information and added database migrations for balance and allowance tables

examples/generic/retriever.go

@@ -0,0 +1,126 @@
+// Copyright 2018 Vulcanize
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package generic
+
+import (
+	"fmt"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
+	"log"
+)
+
+// Retriever is used to iterate over addresses going into or out of a contract
+// address in an attempt to generate a list of token holder addresses
+
+type RetrieverInterface interface {
+	RetrieveSendingAddresses() ([]string, error)
+	RetrieveReceivingAddresses() ([]string, error)
+	RetrieveContractAssociatedAddresses() (map[common.Address]bool, error)
+}
+
+type Retriever struct {
+	Database        *postgres.DB
+	ContractAddress string
+}
+
+type retrieverError struct {
+	err     string
+	msg     string
+	address string
+}
+
+// Retriever error method
+func (re *retrieverError) Error() string {
+	return fmt.Sprintf(re.msg, re.address, re.err)
+}
+
+// Used to create a new retriever error for a given error and fetch method
+func newRetrieverError(err error, msg string, address string) error {
+	e := retrieverError{err.Error(), msg, address}
+	log.Println(e.Error())
+	return &e
+}
+
+// Constant error definitions
+const (
+	GetSenderError   = "Error fetching addresses receiving from contract %s: %s"
+	GetReceiverError = "Error fetching addresses sending to contract %s: %s"
+)
+
+func NewRetriever(db *postgres.DB, address string) Retriever {
+	return Retriever{
+		Database:        db,
+		ContractAddress: address,
+	}
+}
+
+func (rt Retriever) RetrieveReceivingAddresses() ([]string, error) {
+
+	receiversFromContract := make([]string, 0)
+
+	err := rt.Database.DB.Select(
+		&receiversFromContract,
+		`SELECT tx_to FROM TRANSACTIONS
+               WHERE tx_from = $1
+			   LIMIT 20`,
+		rt.ContractAddress,
+	)
+	if err != nil {
+		return []string{}, newRetrieverError(err, GetReceiverError, rt.ContractAddress)
+	}
+	return receiversFromContract, err
+}
+
+func (rt Retriever) RetrieveSendingAddresses() ([]string, error) {
+
+	sendersToContract := make([]string, 0)
+
+	err := rt.Database.DB.Select(
+		&sendersToContract,
+		`SELECT tx_from FROM TRANSACTIONS
+			WHERE tx_to = $1
+		    LIMIT 20`,
+		rt.ContractAddress,
+	)
+	if err != nil {
+		return []string{}, newRetrieverError(err, GetSenderError, rt.ContractAddress)
+	}
+	return sendersToContract, err
+}
+
+func (rt Retriever) RetrieveContractAssociatedAddresses() (map[common.Address]bool, error) {
+
+	sending, err := rt.RetrieveSendingAddresses()
+	if err != nil {
+		return nil, err
+	}
+
+	receiving, err := rt.RetrieveReceivingAddresses()
+	if err != nil {
+		return nil, err
+	}
+
+	contractAddresses := make(map[common.Address]bool)
+
+	for _, addr := range sending {
+		contractAddresses[common.HexToAddress(addr)] = true
+	}
+
+	for _, addr := range receiving {
+		contractAddresses[common.HexToAddress(addr)] = true
+	}
+
+	return contractAddresses, nil
+}