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/*
SPDX-License-Identifier: Apache-2.0
*/
// ====CHAINCODE EXECUTION SAMPLES (CLI) ==================
// ==== Invoke marbles ====
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["initMarble","marble1","blue","35","tom"]}'
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["initMarble","marble2","red","50","tom"]}'
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["initMarble","marble3","blue","70","tom"]}'
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["transferMarble","marble2","jerry"]}'
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["transferMarblesBasedOnColor","blue","jerry"]}'
// peer chaincode invoke -C myc1 -n marbles -c '{"Args":["delete","marble1"]}'
// ==== Query marbles ====
// peer chaincode query -C myc1 -n marbles -c '{"Args":["readMarble","marble1"]}'
// peer chaincode query -C myc1 -n marbles -c '{"Args":["getMarblesByRange","marble1","marble3"]}'
// peer chaincode query -C myc1 -n marbles -c '{"Args":["getHistoryForMarble","marble1"]}'
// Rich Query (Only supported if CouchDB is used as state database):
// peer chaincode query -C myc1 -n marbles -c '{"Args":["queryMarblesByOwner","tom"]}'
// peer chaincode query -C myc1 -n marbles -c '{"Args":["queryMarbles","{\"selector\":{\"owner\":\"tom\"}}"]}'
// Rich Query with Pagination (Only supported if CouchDB is used as state database):
// peer chaincode query -C myc1 -n marbles -c '{"Args":["queryMarblesWithPagination","{\"selector\":{\"owner\":\"tom\"}}","3",""]}'
// INDEXES TO SUPPORT COUCHDB RICH QUERIES
//
// Indexes in CouchDB are required in order to make JSON queries efficient and are required for
// any JSON query with a sort. As of Hyperledger Fabric 1.1, indexes may be packaged alongside
// chaincode in a META-INF/statedb/couchdb/indexes directory. Each index must be defined in its own
// text file with extension *.json with the index definition formatted in JSON following the
// CouchDB index JSON syntax as documented at:
// http://docs.couchdb.org/en/2.1.1/api/database/find.html#db-index
//
// This marbles02 example chaincode demonstrates a packaged
// index which you can find in META-INF/statedb/couchdb/indexes/indexOwner.json.
// For deployment of chaincode to production environments, it is recommended
// to define any indexes alongside chaincode so that the chaincode and supporting indexes
// are deployed automatically as a unit, once the chaincode has been installed on a peer and
// instantiated on a channel. See Hyperledger Fabric documentation for more details.
//
// If you have access to the your peer's CouchDB state database in a development environment,
// you may want to iteratively test various indexes in support of your chaincode queries. You
// can use the CouchDB Fauxton interface or a command line curl utility to create and update
// indexes. Then once you finalize an index, include the index definition alongside your
// chaincode in the META-INF/statedb/couchdb/indexes directory, for packaging and deployment
// to managed environments.
//
// In the examples below you can find index definitions that support marbles02
// chaincode queries, along with the syntax that you can use in development environments
// to create the indexes in the CouchDB Fauxton interface or a curl command line utility.
//
//Example hostname:port configurations to access CouchDB.
//
//To access CouchDB docker container from within another docker container or from vagrant environments:
// http://couchdb:5984/
//
//Inside couchdb docker container
// http://127.0.0.1:5984/
// Index for docType, owner.
//
// Example curl command line to define index in the CouchDB channel_chaincode database
// curl -i -X POST -H "Content-Type: application/json" -d "{\"index\":{\"fields\":[\"docType\",\"owner\"]},\"name\":\"indexOwner\",\"ddoc\":\"indexOwnerDoc\",\"type\":\"json\"}" http://hostname:port/myc1_marbles/_index
//
// Index for docType, owner, size (descending order).
//
// Example curl command line to define index in the CouchDB channel_chaincode database
// curl -i -X POST -H "Content-Type: application/json" -d "{\"index\":{\"fields\":[{\"size\":\"desc\"},{\"docType\":\"desc\"},{\"owner\":\"desc\"}]},\"ddoc\":\"indexSizeSortDoc\", \"name\":\"indexSizeSortDesc\",\"type\":\"json\"}" http://hostname:port/myc1_marbles/_index
// Rich Query with index design doc and index name specified (Only supported if CouchDB is used as state database):
// peer chaincode query -C myc1 -n marbles -c '{"Args":["queryMarbles","{\"selector\":{\"docType\":\"marble\",\"owner\":\"tom\"}, \"use_index\":[\"_design/indexOwnerDoc\", \"indexOwner\"]}"]}'
// Rich Query with index design doc specified only (Only supported if CouchDB is used as state database):
// peer chaincode query -C myc1 -n marbles -c '{"Args":["queryMarbles","{\"selector\":{\"docType\":{\"$eq\":\"marble\"},\"owner\":{\"$eq\":\"tom\"},\"size\":{\"$gt\":0}},\"fields\":[\"docType\",\"owner\",\"size\"],\"sort\":[{\"size\":\"desc\"}],\"use_index\":\"_design/indexSizeSortDoc\"}"]}'
package main
import (
"bytes"
"encoding/json"
"fmt"
"strconv"
"strings"
"time"
"github.com/hyperledger/fabric/core/chaincode/shim"
pb "github.com/hyperledger/fabric/protos/peer"
)
// SimpleChaincode example simple Chaincode implementation
type SimpleChaincode struct {
}
type marble struct {
ObjectType string `json:"docType"` //docType is used to distinguish the various types of objects in state database
Name string `json:"name"` //the fieldtags are needed to keep case from bouncing around
Color string `json:"color"`
Size int `json:"size"`
Owner string `json:"owner"`
}
// ===================================================================================
// Main
// ===================================================================================
func main() {
err := shim.Start(new(SimpleChaincode))
if err != nil {
fmt.Printf("Error starting Simple chaincode: %s", err)
}
}
// Init initializes chaincode
// ===========================
func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
return shim.Success(nil)
}
// Invoke - Our entry point for Invocations
// ========================================
func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
function, args := stub.GetFunctionAndParameters()
fmt.Println("invoke is running " + function)
// Handle different functions
if function == "initMarble" { //create a new marble
return t.initMarble(stub, args)
} else if function == "transferMarble" { //change owner of a specific marble
return t.transferMarble(stub, args)
} else if function == "transferMarblesBasedOnColor" { //transfer all marbles of a certain color
return t.transferMarblesBasedOnColor(stub, args)
} else if function == "delete" { //delete a marble
return t.delete(stub, args)
} else if function == "readMarble" { //read a marble
return t.readMarble(stub, args)
} else if function == "queryMarblesByOwner" { //find marbles for owner X using rich query
return t.queryMarblesByOwner(stub, args)
} else if function == "queryMarbles" { //find marbles based on an ad hoc rich query
return t.queryMarbles(stub, args)
} else if function == "getHistoryForMarble" { //get history of values for a marble
return t.getHistoryForMarble(stub, args)
} else if function == "getMarblesByRange" { //get marbles based on range query
return t.getMarblesByRange(stub, args)
} else if function == "getMarblesByRangeWithPagination" {
return t.getMarblesByRangeWithPagination(stub, args)
} else if function == "queryMarblesWithPagination" {
return t.queryMarblesWithPagination(stub, args)
}
fmt.Println("invoke did not find func: " + function) //error
return shim.Error("Received unknown function invocation")
}
// ============================================================
// initMarble - create a new marble, store into chaincode state
// ============================================================
func (t *SimpleChaincode) initMarble(stub shim.ChaincodeStubInterface, args []string) pb.Response {
var err error
// 0 1 2 3
// "asdf", "blue", "35", "bob"
if len(args) != 4 {
return shim.Error("Incorrect number of arguments. Expecting 4")
}
// ==== Input sanitation ====
fmt.Println("- start init marble")
if len(args[0]) <= 0 {
return shim.Error("1st argument must be a non-empty string")
}
if len(args[1]) <= 0 {
return shim.Error("2nd argument must be a non-empty string")
}
if len(args[2]) <= 0 {
return shim.Error("3rd argument must be a non-empty string")
}
if len(args[3]) <= 0 {
return shim.Error("4th argument must be a non-empty string")
}
marbleName := args[0]
color := strings.ToLower(args[1])
owner := strings.ToLower(args[3])
size, err := strconv.Atoi(args[2])
if err != nil {
return shim.Error("3rd argument must be a numeric string")
}
// ==== Check if marble already exists ====
marbleAsBytes, err := stub.GetState(marbleName)
if err != nil {
return shim.Error("Failed to get marble: " + err.Error())
} else if marbleAsBytes != nil {
fmt.Println("This marble already exists: " + marbleName)
return shim.Error("This marble already exists: " + marbleName)
}
// ==== Create marble object and marshal to JSON ====
objectType := "marble"
marble := &marble{objectType, marbleName, color, size, owner}
marbleJSONasBytes, err := json.Marshal(marble)
if err != nil {
return shim.Error(err.Error())
}
//Alternatively, build the marble json string manually if you don't want to use struct marshalling
//marbleJSONasString := `{"docType":"Marble", "name": "` + marbleName + `", "color": "` + color + `", "size": ` + strconv.Itoa(size) + `, "owner": "` + owner + `"}`
//marbleJSONasBytes := []byte(str)
// === Save marble to state ===
err = stub.PutState(marbleName, marbleJSONasBytes)
if err != nil {
return shim.Error(err.Error())
}
// ==== Index the marble to enable color-based range queries, e.g. return all blue marbles ====
// An 'index' is a normal key/value entry in state.
// The key is a composite key, with the elements that you want to range query on listed first.
// In our case, the composite key is based on indexName~color~name.
// This will enable very efficient state range queries based on composite keys matching indexName~color~*
indexName := "color~name"
colorNameIndexKey, err := stub.CreateCompositeKey(indexName, []string{marble.Color, marble.Name})
if err != nil {
return shim.Error(err.Error())
}
// Save index entry to state. Only the key name is needed, no need to store a duplicate copy of the marble.
// Note - passing a 'nil' value will effectively delete the key from state, therefore we pass null character as value
value := []byte{0x00}
stub.PutState(colorNameIndexKey, value)
// ==== Marble saved and indexed. Return success ====
fmt.Println("- end init marble")
return shim.Success(nil)
}
// ===============================================
// readMarble - read a marble from chaincode state
// ===============================================
func (t *SimpleChaincode) readMarble(stub shim.ChaincodeStubInterface, args []string) pb.Response {
var name, jsonResp string
var err error
if len(args) != 1 {
return shim.Error("Incorrect number of arguments. Expecting name of the marble to query")
}
name = args[0]
valAsbytes, err := stub.GetState(name) //get the marble from chaincode state
if err != nil {
jsonResp = "{\"Error\":\"Failed to get state for " + name + "\"}"
return shim.Error(jsonResp)
} else if valAsbytes == nil {
jsonResp = "{\"Error\":\"Marble does not exist: " + name + "\"}"
return shim.Error(jsonResp)
}
return shim.Success(valAsbytes)
}
// ==================================================
// delete - remove a marble key/value pair from state
// ==================================================
func (t *SimpleChaincode) delete(stub shim.ChaincodeStubInterface, args []string) pb.Response {
var jsonResp string
var marbleJSON marble
if len(args) != 1 {
return shim.Error("Incorrect number of arguments. Expecting 1")
}
marbleName := args[0]
// to maintain the color~name index, we need to read the marble first and get its color
valAsbytes, err := stub.GetState(marbleName) //get the marble from chaincode state
if err != nil {
jsonResp = "{\"Error\":\"Failed to get state for " + marbleName + "\"}"
return shim.Error(jsonResp)
} else if valAsbytes == nil {
jsonResp = "{\"Error\":\"Marble does not exist: " + marbleName + "\"}"
return shim.Error(jsonResp)
}
err = json.Unmarshal([]byte(valAsbytes), &marbleJSON)
if err != nil {
jsonResp = "{\"Error\":\"Failed to decode JSON of: " + marbleName + "\"}"
return shim.Error(jsonResp)
}
err = stub.DelState(marbleName) //remove the marble from chaincode state
if err != nil {
return shim.Error("Failed to delete state:" + err.Error())
}
// maintain the index
indexName := "color~name"
colorNameIndexKey, err := stub.CreateCompositeKey(indexName, []string{marbleJSON.Color, marbleJSON.Name})
if err != nil {
return shim.Error(err.Error())
}
// Delete index entry to state.
err = stub.DelState(colorNameIndexKey)
if err != nil {
return shim.Error("Failed to delete state:" + err.Error())
}
return shim.Success(nil)
}
// ===========================================================
// transfer a marble by setting a new owner name on the marble
// ===========================================================
func (t *SimpleChaincode) transferMarble(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0 1
// "name", "bob"
if len(args) < 2 {
return shim.Error("Incorrect number of arguments. Expecting 2")
}
marbleName := args[0]
newOwner := strings.ToLower(args[1])
fmt.Println("- start transferMarble ", marbleName, newOwner)
marbleAsBytes, err := stub.GetState(marbleName)
if err != nil {
return shim.Error("Failed to get marble:" + err.Error())
} else if marbleAsBytes == nil {
return shim.Error("Marble does not exist")
}
marbleToTransfer := marble{}
err = json.Unmarshal(marbleAsBytes, &marbleToTransfer) //unmarshal it aka JSON.parse()
if err != nil {
return shim.Error(err.Error())
}
marbleToTransfer.Owner = newOwner //change the owner
marbleJSONasBytes, _ := json.Marshal(marbleToTransfer)
err = stub.PutState(marbleName, marbleJSONasBytes) //rewrite the marble
if err != nil {
return shim.Error(err.Error())
}
fmt.Println("- end transferMarble (success)")
return shim.Success(nil)
}
// ===========================================================================================
// constructQueryResponseFromIterator constructs a JSON array containing query results from
// a given result iterator
// ===========================================================================================
func constructQueryResponseFromIterator(resultsIterator shim.StateQueryIteratorInterface) (*bytes.Buffer, error) {
// buffer is a JSON array containing QueryResults
var buffer bytes.Buffer
buffer.WriteString("[")
bArrayMemberAlreadyWritten := false
for resultsIterator.HasNext() {
queryResponse, err := resultsIterator.Next()
if err != nil {
return nil, err
}
// Add a comma before array members, suppress it for the first array member
if bArrayMemberAlreadyWritten == true {
buffer.WriteString(",")
}
buffer.WriteString("{\"Key\":")
buffer.WriteString("\"")
buffer.WriteString(queryResponse.Key)
buffer.WriteString("\"")
buffer.WriteString(", \"Record\":")
// Record is a JSON object, so we write as-is
buffer.WriteString(string(queryResponse.Value))
buffer.WriteString("}")
bArrayMemberAlreadyWritten = true
}
buffer.WriteString("]")
return &buffer, nil
}
// ===========================================================================================
// addPaginationMetadataToQueryResults adds QueryResponseMetadata, which contains pagination
// info, to the constructed query results
// ===========================================================================================
func addPaginationMetadataToQueryResults(buffer *bytes.Buffer, responseMetadata *pb.QueryResponseMetadata) *bytes.Buffer {
buffer.WriteString("[{\"ResponseMetadata\":{\"RecordsCount\":")
buffer.WriteString("\"")
buffer.WriteString(fmt.Sprintf("%v", responseMetadata.FetchedRecordsCount))
buffer.WriteString("\"")
buffer.WriteString(", \"Bookmark\":")
buffer.WriteString("\"")
buffer.WriteString(responseMetadata.Bookmark)
buffer.WriteString("\"}}]")
return buffer
}
// ===========================================================================================
// getMarblesByRange performs a range query based on the start and end keys provided.
// Read-only function results are not typically submitted to ordering. If the read-only
// results are submitted to ordering, or if the query is used in an update transaction
// and submitted to ordering, then the committing peers will re-execute to guarantee that
// result sets are stable between endorsement time and commit time. The transaction is
// invalidated by the committing peers if the result set has changed between endorsement
// time and commit time.
// Therefore, range queries are a safe option for performing update transactions based on query results.
// ===========================================================================================
func (t *SimpleChaincode) getMarblesByRange(stub shim.ChaincodeStubInterface, args []string) pb.Response {
if len(args) < 2 {
return shim.Error("Incorrect number of arguments. Expecting 2")
}
startKey := args[0]
endKey := args[1]
resultsIterator, err := stub.GetStateByRange(startKey, endKey)
if err != nil {
return shim.Error(err.Error())
}
defer resultsIterator.Close()
buffer, err := constructQueryResponseFromIterator(resultsIterator)
if err != nil {
return shim.Error(err.Error())
}
fmt.Printf("- getMarblesByRange queryResult:\n%s\n", buffer.String())
return shim.Success(buffer.Bytes())
}
// ==== Example: GetStateByPartialCompositeKey/RangeQuery =========================================
// transferMarblesBasedOnColor will transfer marbles of a given color to a certain new owner.
// Uses a GetStateByPartialCompositeKey (range query) against color~name 'index'.
// Committing peers will re-execute range queries to guarantee that result sets are stable
// between endorsement time and commit time. The transaction is invalidated by the
// committing peers if the result set has changed between endorsement time and commit time.
// Therefore, range queries are a safe option for performing update transactions based on query results.
// ===========================================================================================
func (t *SimpleChaincode) transferMarblesBasedOnColor(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0 1
// "color", "bob"
if len(args) < 2 {
return shim.Error("Incorrect number of arguments. Expecting 2")
}
color := args[0]
newOwner := strings.ToLower(args[1])
fmt.Println("- start transferMarblesBasedOnColor ", color, newOwner)
// Query the color~name index by color
// This will execute a key range query on all keys starting with 'color'
coloredMarbleResultsIterator, err := stub.GetStateByPartialCompositeKey("color~name", []string{color})
if err != nil {
return shim.Error(err.Error())
}
defer coloredMarbleResultsIterator.Close()
// Iterate through result set and for each marble found, transfer to newOwner
var i int
for i = 0; coloredMarbleResultsIterator.HasNext(); i++ {
// Note that we don't get the value (2nd return variable), we'll just get the marble name from the composite key
responseRange, err := coloredMarbleResultsIterator.Next()
if err != nil {
return shim.Error(err.Error())
}
// get the color and name from color~name composite key
objectType, compositeKeyParts, err := stub.SplitCompositeKey(responseRange.Key)
if err != nil {
return shim.Error(err.Error())
}
returnedColor := compositeKeyParts[0]
returnedMarbleName := compositeKeyParts[1]
fmt.Printf("- found a marble from index:%s color:%s name:%s\n", objectType, returnedColor, returnedMarbleName)
// Now call the transfer function for the found marble.
// Re-use the same function that is used to transfer individual marbles
response := t.transferMarble(stub, []string{returnedMarbleName, newOwner})
// if the transfer failed break out of loop and return error
if response.Status != shim.OK {
return shim.Error("Transfer failed: " + response.Message)
}
}
responsePayload := fmt.Sprintf("Transferred %d %s marbles to %s", i, color, newOwner)
fmt.Println("- end transferMarblesBasedOnColor: " + responsePayload)
return shim.Success([]byte(responsePayload))
}
// =======Rich queries =========================================================================
// Two examples of rich queries are provided below (parameterized query and ad hoc query).
// Rich queries pass a query string to the state database.
// Rich queries are only supported by state database implementations
// that support rich query (e.g. CouchDB).
// The query string is in the syntax of the underlying state database.
// With rich queries there is no guarantee that the result set hasn't changed between
// endorsement time and commit time, aka 'phantom reads'.
// Therefore, rich queries should not be used in update transactions, unless the
// application handles the possibility of result set changes between endorsement and commit time.
// Rich queries can be used for point-in-time queries against a peer.
// ============================================================================================
// ===== Example: Parameterized rich query =================================================
// queryMarblesByOwner queries for marbles based on a passed in owner.
// This is an example of a parameterized query where the query logic is baked into the chaincode,
// and accepting a single query parameter (owner).
// Only available on state databases that support rich query (e.g. CouchDB)
// =========================================================================================
func (t *SimpleChaincode) queryMarblesByOwner(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0
// "bob"
if len(args) < 1 {
return shim.Error("Incorrect number of arguments. Expecting 1")
}
owner := strings.ToLower(args[0])
queryString := fmt.Sprintf("{\"selector\":{\"docType\":\"marble\",\"owner\":\"%s\"}}", owner)
queryResults, err := getQueryResultForQueryString(stub, queryString)
if err != nil {
return shim.Error(err.Error())
}
return shim.Success(queryResults)
}
// ===== Example: Ad hoc rich query ========================================================
// queryMarbles uses a query string to perform a query for marbles.
// Query string matching state database syntax is passed in and executed as is.
// Supports ad hoc queries that can be defined at runtime by the client.
// If this is not desired, follow the queryMarblesForOwner example for parameterized queries.
// Only available on state databases that support rich query (e.g. CouchDB)
// =========================================================================================
func (t *SimpleChaincode) queryMarbles(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0
// "queryString"
if len(args) < 1 {
return shim.Error("Incorrect number of arguments. Expecting 1")
}
queryString := args[0]
queryResults, err := getQueryResultForQueryString(stub, queryString)
if err != nil {
return shim.Error(err.Error())
}
return shim.Success(queryResults)
}
// =========================================================================================
// getQueryResultForQueryString executes the passed in query string.
// Result set is built and returned as a byte array containing the JSON results.
// =========================================================================================
func getQueryResultForQueryString(stub shim.ChaincodeStubInterface, queryString string) ([]byte, error) {
fmt.Printf("- getQueryResultForQueryString queryString:\n%s\n", queryString)
resultsIterator, err := stub.GetQueryResult(queryString)
if err != nil {
return nil, err
}
defer resultsIterator.Close()
buffer, err := constructQueryResponseFromIterator(resultsIterator)
if err != nil {
return nil, err
}
fmt.Printf("- getQueryResultForQueryString queryResult:\n%s\n", buffer.String())
return buffer.Bytes(), nil
}
// ====== Pagination =========================================================================
// Pagination provides a method to retrieve records with a defined pagesize and
// start point (bookmark). An empty string bookmark defines the first "page" of a query
// result. Paginated queries return a bookmark that can be used in
// the next query to retrieve the next page of results. Paginated queries extend
// rich queries and range queries to include a pagesize and bookmark.
//
// Two examples are provided in this example. The first is getMarblesByRangeWithPagination
// which executes a paginated range query.
// The second example is a paginated query for rich ad-hoc queries.
// =========================================================================================
// ====== Example: Pagination with Range Query ===============================================
// getMarblesByRangeWithPagination performs a range query based on the start & end key,
// page size and a bookmark.
// The number of fetched records will be equal to or lesser than the page size.
// Paginated range queries are only valid for read only transactions.
// ===========================================================================================
func (t *SimpleChaincode) getMarblesByRangeWithPagination(stub shim.ChaincodeStubInterface, args []string) pb.Response {
if len(args) < 4 {
return shim.Error("Incorrect number of arguments. Expecting 4")
}
startKey := args[0]
endKey := args[1]
//return type of ParseInt is int64
pageSize, err := strconv.ParseInt(args[2], 10, 32)
if err != nil {
return shim.Error(err.Error())
}
bookmark := args[3]
resultsIterator, responseMetadata, err := stub.GetStateByRangeWithPagination(startKey, endKey, int32(pageSize), bookmark)
if err != nil {
return shim.Error(err.Error())
}
defer resultsIterator.Close()
buffer, err := constructQueryResponseFromIterator(resultsIterator)
if err != nil {
return shim.Error(err.Error())
}
bufferWithPaginationInfo := addPaginationMetadataToQueryResults(buffer, responseMetadata)
fmt.Printf("- getMarblesByRange queryResult:\n%s\n", bufferWithPaginationInfo.String())
return shim.Success(buffer.Bytes())
}
// ===== Example: Pagination with Ad hoc Rich Query ========================================================
// queryMarblesWithPagination uses a query string, page size and a bookmark to perform a query
// for marbles. Query string matching state database syntax is passed in and executed as is.
// The number of fetched records would be equal to or lesser than the specified page size.
// Supports ad hoc queries that can be defined at runtime by the client.
// If this is not desired, follow the queryMarblesForOwner example for parameterized queries.
// Only available on state databases that support rich query (e.g. CouchDB)
// Paginated queries are only valid for read only transactions.
// =========================================================================================
func (t *SimpleChaincode) queryMarblesWithPagination(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0
// "queryString"
if len(args) < 3 {
return shim.Error("Incorrect number of arguments. Expecting 3")
}
queryString := args[0]
//return type of ParseInt is int64
pageSize, err := strconv.ParseInt(args[1], 10, 32)
if err != nil {
return shim.Error(err.Error())
}
bookmark := args[2]
queryResults, err := getQueryResultForQueryStringWithPagination(stub, queryString, int32(pageSize), bookmark)
if err != nil {
return shim.Error(err.Error())
}
return shim.Success(queryResults)
}
// =========================================================================================
// getQueryResultForQueryStringWithPagination executes the passed in query string with
// pagination info. Result set is built and returned as a byte array containing the JSON results.
// =========================================================================================
func getQueryResultForQueryStringWithPagination(stub shim.ChaincodeStubInterface, queryString string, pageSize int32, bookmark string) ([]byte, error) {
fmt.Printf("- getQueryResultForQueryString queryString:\n%s\n", queryString)
resultsIterator, responseMetadata, err := stub.GetQueryResultWithPagination(queryString, pageSize, bookmark)
if err != nil {
return nil, err
}
defer resultsIterator.Close()
buffer, err := constructQueryResponseFromIterator(resultsIterator)
if err != nil {
return nil, err
}
bufferWithPaginationInfo := addPaginationMetadataToQueryResults(buffer, responseMetadata)
fmt.Printf("- getQueryResultForQueryString queryResult:\n%s\n", bufferWithPaginationInfo.String())
return buffer.Bytes(), nil
}
func (t *SimpleChaincode) getHistoryForMarble(stub shim.ChaincodeStubInterface, args []string) pb.Response {
if len(args) < 1 {
return shim.Error("Incorrect number of arguments. Expecting 1")
}
marbleName := args[0]
fmt.Printf("- start getHistoryForMarble: %s\n", marbleName)
resultsIterator, err := stub.GetHistoryForKey(marbleName)
if err != nil {
return shim.Error(err.Error())
}
defer resultsIterator.Close()
// buffer is a JSON array containing historic values for the marble
var buffer bytes.Buffer
buffer.WriteString("[")
bArrayMemberAlreadyWritten := false
for resultsIterator.HasNext() {
response, err := resultsIterator.Next()
if err != nil {
return shim.Error(err.Error())
}
// Add a comma before array members, suppress it for the first array member
if bArrayMemberAlreadyWritten == true {
buffer.WriteString(",")
}
buffer.WriteString("{\"TxId\":")
buffer.WriteString("\"")
buffer.WriteString(response.TxId)
buffer.WriteString("\"")
buffer.WriteString(", \"Value\":")
// if it was a delete operation on given key, then we need to set the
//corresponding value null. Else, we will write the response.Value
//as-is (as the Value itself a JSON marble)
if response.IsDelete {
buffer.WriteString("null")
} else {
buffer.WriteString(string(response.Value))
}
buffer.WriteString(", \"Timestamp\":")
buffer.WriteString("\"")
buffer.WriteString(time.Unix(response.Timestamp.Seconds, int64(response.Timestamp.Nanos)).String())
buffer.WriteString("\"")
buffer.WriteString(", \"IsDelete\":")
buffer.WriteString("\"")
buffer.WriteString(strconv.FormatBool(response.IsDelete))
buffer.WriteString("\"")
buffer.WriteString("}")
bArrayMemberAlreadyWritten = true
}
buffer.WriteString("]")
fmt.Printf("- getHistoryForMarble returning:\n%s\n", buffer.String())
return shim.Success(buffer.Bytes())
}