FAB-2047 Add delete by ID to CouchDB Layer

Motivation for this change:
Add DeleteDoc method to the CouchDB layer in order to provide
delete by ID capability.  This is a first step to allow the ledger
to delete CouchDB records.

- Add DeleteDoc to couchdb.go

- Add unit tests for delete in couchdb_test.go

Change-Id: I0466bea76f02d16a7c62b07d978a48c20ad80281
Signed-off-by: Chris Elder <[email protected]>

Author: Chris Elder

core/ledger/util/couchdb/couchdb.go

@@ -1,5 +1,5 @@
 /*
-Copyright IBM Corp. 2016 All Rights Reserved.
+Copyright IBM Corp. 2016, 2017 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.
@@ -733,6 +733,55 @@ func (dbclient *CouchDatabase) ReadDocRange(startKey, endKey string, limit, skip
 
 }
 
+//DeleteDoc method provides function to delete a document from the database by id
+func (dbclient *CouchDatabase) DeleteDoc(id, rev string) error {
+
+	logger.Debugf("Entering DeleteDoc()  id=%s", id)
+
+	deleteURL, err := url.Parse(dbclient.couchInstance.conf.URL)
+	if err != nil {
+		logger.Errorf("URL parse error: %s", err.Error())
+		return err
+	}
+
+	deleteURL.Path = dbclient.dbName
+	// id can contain a '/', so encode separately
+	deleteURL = &url.URL{Opaque: deleteURL.String() + "/" + encodePathElement(id)}
+
+	if rev == "" {
+
+		//See if the document already exists, we need the rev for delete
+		_, revdoc, err2 := dbclient.ReadDoc(id)
+		if err2 != nil {
+			//set the revision to indicate that the document was not found
+			rev = ""
+		} else {
+			//set the revision to the rev returned from the document read
+			rev = revdoc
+		}
+	}
+
+	logger.Debugf("  rev=%s", rev)
+
+	resp, couchDBReturn, err := dbclient.handleRequest(http.MethodDelete, deleteURL.String(), nil, rev, "")
+	if err != nil {
+		fmt.Printf("couchDBReturn=%v", couchDBReturn)
+		if couchDBReturn != nil && couchDBReturn.StatusCode == 404 {
+			logger.Debug("Document not found (404), returning nil value instead of 404 error")
+			// non-existent document should return nil value instead of a 404 error
+			// for details see https://github.com/hyperledger-archives/fabric/issues/936
+			return nil
+		}
+		return err
+	}
+	defer resp.Body.Close()
+
+	logger.Debugf("Exiting DeleteDoc()")
+
+	return nil
+
+}
+
 //QueryDocuments method provides function for processing a query
 func (dbclient *CouchDatabase) QueryDocuments(query string, limit, skip int) (*[]QueryResult, error) {
 
@@ -796,7 +845,6 @@ func (dbclient *CouchDatabase) QueryDocuments(query string, limit, skip int) (*[
 
 		logger.Debugf("Adding row to resultset: %s", row)
 
-		//TODO Replace the temporary NewHeight version when available
 		var addDocument = &QueryResult{jsonDoc.ID, row}
 
 		results = append(results, *addDocument)
@@ -821,7 +869,7 @@ func (dbclient *CouchDatabase) handleRequest(method, connectURL string, data io.
 	}
 
 	//add content header for PUT
-	if method == http.MethodPut || method == http.MethodPost {
+	if method == http.MethodPut || method == http.MethodPost || method == http.MethodDelete {
 
 		//If the multipartBoundary is not set, then this is a JSON and content-type should be set
 		//to application/json.   Else, this is contains an attachment and needs to be multipart

core/ledger/util/couchdb/couchdb_test.go

@@ -1,5 +1,5 @@
 /*
-Copyright IBM Corp. 2016 All Rights Reserved.
+Copyright IBM Corp. 2016, 2017 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.
@@ -332,3 +332,60 @@ func TestDBSaveAttachment(t *testing.T) {
 
 	}
 }
+
+func TestDBDeleteDocument(t *testing.T) {
+
+	if ledgerconfig.IsCouchDBEnabled() == true {
+
+		cleanup()
+		defer cleanup()
+
+		//create a new instance and database object
+		couchInstance, err := CreateCouchInstance(connectURL, username, password)
+		testutil.AssertNoError(t, err, fmt.Sprintf("Error when trying to create couch instance"))
+		db := CouchDatabase{couchInstance: *couchInstance, dbName: database}
+
+		//create a new database
+		_, errdb := db.CreateDatabaseIfNotExist()
+		testutil.AssertNoError(t, errdb, fmt.Sprintf("Error when trying to create database"))
+
+		//Save the test document
+		_, saveerr := db.SaveDoc("2", "", assetJSON, nil)
+		testutil.AssertNoError(t, saveerr, fmt.Sprintf("Error when trying to save a document"))
+
+		//Attempt to retrieve the test document
+		_, _, readErr := db.ReadDoc("2")
+		testutil.AssertNoError(t, readErr, fmt.Sprintf("Error when trying to retrieve a document with attachment"))
+
+		//Delete the test document
+		deleteErr := db.DeleteDoc("2", "")
+		testutil.AssertNoError(t, deleteErr, fmt.Sprintf("Error when trying to delete a document"))
+
+		//Attempt to retrieve the test document
+		readValue, _, _ := db.ReadDoc("2")
+		testutil.AssertNil(t, readValue)
+
+	}
+}
+
+func TestDBDeleteNonExistingDocument(t *testing.T) {
+
+	if ledgerconfig.IsCouchDBEnabled() == true {
+
+		cleanup()
+		defer cleanup()
+
+		//create a new instance and database object
+		couchInstance, err := CreateCouchInstance(connectURL, username, password)
+		testutil.AssertNoError(t, err, fmt.Sprintf("Error when trying to create couch instance"))
+		db := CouchDatabase{couchInstance: *couchInstance, dbName: database}
+
+		//create a new database
+		_, errdb := db.CreateDatabaseIfNotExist()
+		testutil.AssertNoError(t, errdb, fmt.Sprintf("Error when trying to create database"))
+
+		//Save the test document
+		deleteErr := db.DeleteDoc("2", "")
+		testutil.AssertNoError(t, deleteErr, fmt.Sprintf("Error when trying to delete a non existing document"))
+	}
+}