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query_response_generator.go
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/
query_response_generator.go
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/*
Copyright IBM Corp. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package chaincode
import (
commonledger "github.com/hyperledger/fabric/common/ledger"
pb "github.com/hyperledger/fabric/protos/peer"
)
type QueryResponseGenerator struct {
MaxResultLimit int
}
// NewQueryResponse takes an iterator and fetch state to construct QueryResponse
func (q *QueryResponseGenerator) BuildQueryResponse(txContext *TransactionContext, iter commonledger.ResultsIterator, iterID string) (*pb.QueryResponse, error) {
pendingQueryResults := txContext.GetPendingQueryResult(iterID)
for {
queryResult, err := iter.Next()
switch {
case err != nil:
chaincodeLogger.Errorf("Failed to get query result from iterator")
txContext.CleanupQueryContext(iterID)
return nil, err
case queryResult == nil:
// nil response from iterator indicates end of query results
batch := pendingQueryResults.Cut()
txContext.CleanupQueryContext(iterID)
return &pb.QueryResponse{Results: batch, HasMore: false, Id: iterID}, nil
case pendingQueryResults.Size() == q.MaxResultLimit:
// max number of results queued up, cut batch, then add current result to pending batch
batch := pendingQueryResults.Cut()
if err := pendingQueryResults.Add(queryResult); err != nil {
txContext.CleanupQueryContext(iterID)
return nil, err
}
return &pb.QueryResponse{Results: batch, HasMore: true, Id: iterID}, nil
default:
if err := pendingQueryResults.Add(queryResult); err != nil {
txContext.CleanupQueryContext(iterID)
return nil, err
}
}
}
}