Modify example 'chaincode_example_06'

-Rename example to 'attributes_to_state' avoiding 'chaincode_example_XX'
 pattern.
-Rename ambiguous functions "query" and "invoke" to "read" and "submit"
 respectively.
-Fix a compilation error.

Why:
Fixes #2235
#2235

Checklist:
X I have added a Signed-off-by.
X This change requires no new documentation.
X This change requires no new tests.
X I have run golint and have fixed valid warnings in code I have added
  or modified.

Change-Id: Ib15f49d91620ec633019115f81298e95d3473928
Signed-off-by: agaragiola <[email protected]>

Author: agaragiola

examples/chaincode/go/attributes_to_state/attributes_to_state.go

@@ -0,0 +1,146 @@
+/*
+Copyright IBM Corp. 2016 All Rights Reserved.
+
+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 main
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/hyperledger/fabric/core/chaincode/shim"
+	"github.com/hyperledger/fabric/core/chaincode/shim/crypto/attr"
+)
+
+// Attributes2State demonstrates how to read attributes from TCerts.
+type Attributes2State struct {
+}
+
+func (t *Attributes2State) setStateToAttributes(stub *shim.ChaincodeStub, args []string) error {
+	attrHandler, err := attr.NewAttributesHandlerImpl(stub)
+	if err != nil {
+		return err
+	}
+	for _, att := range args {
+		fmt.Println("Writing attribute " + att)
+		attVal, err := attrHandler.GetValue(att)
+		if err != nil {
+			return err
+		}
+		err = stub.PutState(att, attVal)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Init intializes the chaincode by reading the transaction attributes and storing
+// the attrbute values in the state
+func (t *Attributes2State) Init(stub *shim.ChaincodeStub, function string, args []string) ([]byte, error) {
+	err := t.setStateToAttributes(stub, args)
+	if err != nil {
+		return nil, err
+	}
+	return nil, nil
+}
+
+// Invoke takes two arguements, a key and value, and stores these in the state
+func (t *Attributes2State) Invoke(stub *shim.ChaincodeStub, function string, args []string) ([]byte, error) {
+	if function == "delete" {
+		return nil, t.delete(stub, args)
+	}
+
+	if function != "submit" {
+		return nil, errors.New("Invalid invoke function name. Expecting either \"delete\" or \"submit\"")
+	}
+	err := t.setStateToAttributes(stub, args)
+	if err != nil {
+		return nil, err
+	}
+	return nil, nil
+}
+
+// delete Deletes an entity from the state, returning error if the entity was not found in the state.
+func (t *Attributes2State) delete(stub *shim.ChaincodeStub, args []string) error {
+	if len(args) != 1 {
+		return errors.New("Incorrect number of arguments. Expecting only 1 (attributeName)")
+	}
+
+	attributeName := args[0]
+	fmt.Printf("Deleting attribute %v", attributeName)
+	valBytes, err := stub.GetState(attributeName)
+	if err != nil {
+		return err
+	}
+
+	if valBytes == nil {
+		return errors.New("Attribute '" + attributeName + "' not found.")
+	}
+
+	isOk, err := stub.VerifyAttribute(attributeName, valBytes)
+	if err != nil {
+		return err
+	}
+	if isOk {
+		// Delete the key from the state in ledger
+		err = stub.DelState(attributeName)
+		if err != nil {
+			return errors.New("Failed to delete state")
+		}
+	}
+	return nil
+}
+
+// Query callback representing the query of a chaincode
+func (t *Attributes2State) Query(stub *shim.ChaincodeStub, function string, args []string) ([]byte, error) {
+	if function != "read" {
+		return nil, errors.New("Invalid query function name. Expecting \"read\"")
+	}
+	var attributeName string // Name of the attributeName to query.
+	var err error
+
+	if len(args) != 1 {
+		return nil, errors.New("Incorrect number of arguments. Expecting only 1 (attributeName)")
+	}
+
+	attributeName = args[0]
+	fmt.Printf("Reading attribute %v", attributeName)
+
+	// Get the state from the ledger
+	Avalbytes, err := stub.GetState(attributeName)
+	if err != nil {
+		jsonResp := "{\"Error\":\"Failed to get state for " + attributeName + "\"}"
+		fmt.Printf("Query Response:%s\n", jsonResp)
+		return nil, errors.New(jsonResp)
+	}
+
+	if Avalbytes == nil {
+		jsonResp := "{\"Error\":\"Nil amount for " + attributeName + "\"}"
+		fmt.Printf("Query Response:%s\n", jsonResp)
+		return nil, errors.New(jsonResp)
+	}
+
+	jsonResp := "{\"Name\":\"" + attributeName + "\",\"Amount\":\"" + string(Avalbytes) + "\"}"
+	fmt.Printf("Query Response:%s\n", jsonResp)
+	return []byte(jsonResp), nil
+}
+
+func main() {
+	err := shim.Start(new(Attributes2State))
+	if err != nil {
+		fmt.Printf("Error running Attributes2State chaincode: %s", err)
+	}
+}