Improve Datastore example to support insert-list-delete.

Examples/Datastore/PackageManager/Sources/main.swift

@@ -26,6 +26,7 @@ struct Thing : Codable {
   var number: Int
 }
 
+// Convert Encodable objects to dictionaries of property-value pairs.
 class PropertiesEncoder {
   static func encode<T : Encodable>(_ value : T) throws -> [String:Any]? {
     let plist = try PropertyListEncoder().encode(value)
@@ -34,6 +35,7 @@ class PropertiesEncoder {
   }
 }
 
+// Create Decodable objects from dictionaries of property-value pairs.
 class PropertiesDecoder {
   static func decode<T: Decodable>(_ type: T.Type, from: [String:Any]) throws -> T {
     let plist = try PropertyListSerialization.data(fromPropertyList: from,
@@ -42,14 +44,42 @@ class PropertiesDecoder {
   }
 }
 
-func runSelectQuery(service: Google_Datastore_V1_DatastoreService) throws {
+func prepareService() throws -> Google_Datastore_V1_DatastoreService? {
+  // Get an OAuth token
+  var authToken : String!
+  if let provider = DefaultTokenProvider(scopes:scopes) {
+    let sem = DispatchSemaphore(value: 0)
+    try provider.withToken() {(token, error) -> Void in
+      if let token = token {
+        authToken = token.AccessToken
+      }
+      sem.signal()
+    }
+    sem.wait()
+  }
+  if authToken == nil {
+    print("ERROR: No OAuth token is available. Did you set GOOGLE_APPLICATION_CREDENTIALS?")
+    exit(-1)
+  }
+  // Initialize gRPC service
+  gRPC.initialize()
+  let certificateURL = URL(fileURLWithPath:"/roots.pem")
+  let certificates = try! String(contentsOf: certificateURL, encoding: .utf8)
+  let service = Google_Datastore_V1_DatastoreService(address:"datastore.googleapis.com",
+                                                     certificates:certificates,
+                                                     host:nil)
+  service.metadata = Metadata(["authorization":"Bearer " + authToken])
+  return service
+}
+
+func performList(service: Google_Datastore_V1_DatastoreService) throws {
   var request = Google_Datastore_V1_RunQueryRequest()
   request.projectID = projectID
   var query = Google_Datastore_V1_GqlQuery()
   query.queryString = "select * from Thing"
   request.gqlQuery = query
   let result = try service.runquery(request)
-  var entities : [Thing] = []
+  var entities : [Int64 : Thing] = [:]
   for entityResult in result.batch.entityResults {
     var properties : [String:Any] = [:]
     for property in entityResult.entity.properties {
@@ -64,12 +94,12 @@ func runSelectQuery(service: Google_Datastore_V1_DatastoreService) throws {
       }
     }
     let entity = try PropertiesDecoder.decode(Thing.self, from:properties)
-    entities.append(entity)
+    entities[entityResult.entity.key.path[0].id] = entity
   }
   print("\(entities)")
 }
 
-func runInsert(service: Google_Datastore_V1_DatastoreService,
+func performInsert(service: Google_Datastore_V1_DatastoreService,
                number: Int) throws {
   var request = Google_Datastore_V1_CommitRequest()
   request.projectID = projectID
@@ -94,19 +124,16 @@ func runInsert(service: Google_Datastore_V1_DatastoreService,
     }
     entity.properties[k] = value
   }
-  
   var mutation = Google_Datastore_V1_Mutation()
   mutation.insert = entity
   request.mutations.append(mutation)
-  
   let result = try service.commit(request)
-
   for mutationResult in result.mutationResults {
     print("\(mutationResult)")
   }
 }
 
-func runDelete(service: Google_Datastore_V1_DatastoreService,
+func performDelete(service: Google_Datastore_V1_DatastoreService,
                kind: String,
                id: Int64) throws {
   var request = Google_Datastore_V1_CommitRequest()
@@ -126,50 +153,22 @@ func runDelete(service: Google_Datastore_V1_DatastoreService,
   }
 }
 
-func prepareService() throws -> Google_Datastore_V1_DatastoreService? {
-  // Get an OAuth token
-  var authToken : String!
-  if let provider = DefaultTokenProvider(scopes:scopes) {
-    let sem = DispatchSemaphore(value: 0)
-    try provider.withToken() {(token, error) -> Void in
-      if let token = token {
-        authToken = token.AccessToken
-      }
-      sem.signal()
-    }
-    sem.wait()
-  }
-  if authToken == nil {
-    print("ERROR: No OAuth token is available. Did you set GOOGLE_APPLICATION_CREDENTIALS?")
-    exit(-1)
-  }
-  // Initialize gRPC service
-  gRPC.initialize()
-  let certificateURL = URL(fileURLWithPath:"/roots.pem")
-  let certificates = try! String(contentsOf: certificateURL, encoding: .utf8)
-  let service = Google_Datastore_V1_DatastoreService(address:"datastore.googleapis.com",
-                                                     certificates:certificates,
-                                                     host:nil)
-  service.metadata = Metadata(["authorization":"Bearer " + authToken])
-  return service
-}
-
 Group {
   $0.command("insert") { (number:Int) in
     if let service = try prepareService() {
-      try runInsert(service:service, number:number)
+      try performInsert(service:service, number:number)
     }
   }
 
   $0.command("delete") { (id:Int) in
     if let service = try prepareService() {
-      try runDelete(service:service, kind:"Thing", id:Int64(id))
+      try performDelete(service:service, kind:"Thing", id:Int64(id))
     }
   }
   
-  $0.command("query") {
+  $0.command("list") {
     if let service = try prepareService() {
-      try runSelectQuery(service:service)
+      try performList(service:service)
     }
   }