Merge pull request #49 from itzmeanjan/develop

REST & GraphQL API for fetching event log using block hash/ number & log index

README.md

@@ -304,6 +304,8 @@ Query Params | Method | Description
 Query Params | Method | Description
 --- | --- | ---
 `blockHash=0x...` | GET | Given blockhash, retrieves all events emitted by tx(s) present in block
+`blockHash=0x...&logIndex=1` | GET | Given blockhash and log index in block, attempts to retrieve associated event
+`blockNumber=123456&logIndex=2` | GET | Given block number and log index in block, attempts to retrieve associated event
 `txHash=0x...` | GET | Given txhash, retrieves all events emitted during execution of this transaction
 `count=50&contract=0x...` | GET | Returns last **x** _( <=50 )_ events emitted by this contract
 `fromBlock=1&toBlock=10&contract=0x...&topic0=0x...&topic1=0x...&topic2=0x...&topic3=0x...` | GET | Finding event(s) emitted from contract within given block range & also matching topic signatures _{0, 1, 2, 3}_
@@ -386,6 +388,8 @@ type Transaction {
   from: String!
   to: String!
   contract: String!
+  value: String!
+  data: String!
   gas: String!
   gasPrice: String!
   cost: String!
@@ -412,6 +416,8 @@ type Query {
     eventsFromContractWithTopicsByNumberRange(contract: String!, from: String!, to: String!, topics: [String!]!): [Event!]!
     eventsFromContractWithTopicsByTimeRange(contract: String!, from: String!, to: String!, topics: [String!]!): [Event!]!
     lastXEventsFromContract(contract: String!, x: Int!): [Event!]!
+    eventByBlockHashAndLogIndex(hash: String!, index: String!): Event!
+    eventByBlockNumberAndLogIndex(number: String!, index: String!): Event!
 }
 ```
 

app/db/query.go

@@ -428,3 +428,39 @@ func GetLastXEventsFromContract(db *gorm.DB, contract common.Address, x int) *da
 	}
 
 }
+
+// GetEventByBlockHashAndLogIndex - Given block hash and log index in block
+// return respective event log, if any exists
+func GetEventByBlockHashAndLogIndex(db *gorm.DB, hash common.Hash, index uint) *data.Event {
+
+	var event data.Event
+
+	if err := db.Model(&Events{}).Where("blockhash = ? and index = ?", hash.Hex(), index).First(&event).Error; err != nil {
+		return nil
+	}
+
+	return &event
+
+}
+
+// GetEventByBlockNumberAndLogIndex - Given block number and log index in block
+// return respective event log, if any exists
+func GetEventByBlockNumberAndLogIndex(db *gorm.DB, number uint64, index uint) *data.Event {
+
+	block := GetBlockByNumber(db, number)
+	// seems bad block number or may be `ette`
+	// hasn't synced upto this point or missed
+	// this block some how
+	if block == nil {
+		return nil
+	}
+
+	var event data.Event
+
+	if err := db.Model(&Events{}).Where("blockhash = ? and index = ?", block.Hash, index).First(&event).Error; err != nil {
+		return nil
+	}
+
+	return &event
+
+}

app/rest/graph/schema.graphqls

@@ -63,4 +63,6 @@ type Query {
   eventsFromContractWithTopicsByNumberRange(contract: String!, from: String!, to: String!, topics: [String!]!): [Event!]!
   eventsFromContractWithTopicsByTimeRange(contract: String!, from: String!, to: String!, topics: [String!]!): [Event!]!
   lastXEventsFromContract(contract: String!, x: Int!): [Event!]!
+  eventByBlockHashAndLogIndex(hash: String!, index: String!): Event!
+  eventByBlockNumberAndLogIndex(number: String!, index: String!): Event!
 }

app/rest/graph/schema.resolvers.go

@@ -281,6 +281,37 @@ func (r *queryResolver) LastXEventsFromContract(ctx context.Context, contract st
 	return getGraphQLCompatibleEvents(_db.GetLastXEventsFromContract(db, common.HexToAddress(contract), x))
 }
 
+func (r *queryResolver) EventByBlockHashAndLogIndex(ctx context.Context, hash string, index string) (*model.Event, error) {
+
+	if !(strings.HasPrefix(hash, "0x") && len(hash) == 66) {
+		return nil, errors.New("Bad Block Hash")
+	}
+
+	_index, err := strconv.ParseUint(index, 10, 64)
+	if err != nil {
+		return nil, errors.New("Bad Log Index")
+	}
+
+	return getGraphQLCompatibleEvent(_db.GetEventByBlockHashAndLogIndex(db, common.HexToHash(hash), uint(_index)))
+
+}
+
+func (r *queryResolver) EventByBlockNumberAndLogIndex(ctx context.Context, number string, index string) (*model.Event, error) {
+
+	_number, err := strconv.ParseUint(number, 10, 64)
+	if err != nil {
+		return nil, errors.New("Bad Block Number")
+	}
+
+	_index, err := strconv.ParseUint(index, 10, 64)
+	if err != nil {
+		return nil, errors.New("Bad Log Index")
+	}
+
+	return getGraphQLCompatibleEvent(_db.GetEventByBlockNumberAndLogIndex(db, _number, uint(_index)))
+
+}
+
 // Query returns generated.QueryResolver implementation.
 func (r *Resolver) Query() generated.QueryResolver { return &queryResolver{r} }