Add a student records console application (#2)

* Add `studentRecordsConsoleApp.cpp` 

Co-authored-by: bisht42 <108942387+bisht42@users.noreply.github.com>

Author: bisht2050

student-records-console-app/studentRecordsConsoleApp.cpp

@@ -0,0 +1,277 @@
+#pragma once
+
+#include <mongocxx/client.hpp>
+#include <bsoncxx/builder/stream/document.hpp>
+#include <bsoncxx/json.hpp>
+#include <mongocxx/uri.hpp>
+#include <mongocxx/instance.hpp>
+
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+std::string getEnvironmentVariable(std::string environmentVarKey)
+{
+	char* pBuffer = nullptr;
+	size_t size = 0;
+	auto key = environmentVarKey.c_str();
+	
+	// Use the secure version of getenv, ie. _dupenv_s to fetch environment variable.  
+	if (_dupenv_s(&pBuffer, &size, key) == 0 && pBuffer != nullptr)
+	{
+		std::string environmentVarValue(pBuffer);
+		free(pBuffer);
+		return environmentVarValue;
+	}
+	else
+	{
+		return "";
+	}
+}
+
+auto mongoURIStr = getEnvironmentVariable("MONGODB_URI");
+static const mongocxx::uri mongoURI = mongocxx::uri{ mongoURIStr };
+
+
+// ********************************************** Database Methods **********************************************
+
+// Get all the databases from a given client.
+vector<string> getDatabases(mongocxx::client& client)
+{
+	return client.list_database_names();
+}
+
+
+// ********************************************** Collection Methods **********************************************
+
+// Create a new collection in the given database.
+void createCollection(mongocxx::database& db, const string& collectionName)
+{
+	db.create_collection(collectionName);
+}
+
+// Print the contents of the given collection.
+void printCollection(mongocxx::collection& collection)
+{
+	// Check if collection is empty.
+	if (collection.count_documents({}) == 0)
+	{
+		cout << "Collection is empty." << endl;
+		return;
+	}
+	
+	auto cursor = collection.find({});
+
+	for (auto&& doc : cursor)
+	{
+		cout << bsoncxx::to_json(doc) << endl;
+	}
+}
+
+// ********************************************** Document Methods **********************************************
+
+// Create a document from the given key-value pairs.
+bsoncxx::document::value createDocument(const vector<pair<string, string>>& keyValues)
+{
+	bsoncxx::builder::stream::document document{};
+
+	for (auto& keyValue : keyValues)
+	{
+		document << keyValue.first << keyValue.second;
+	}
+
+	return document << bsoncxx::builder::stream::finalize;
+}
+
+// Insert a document into the given collection.
+void insertDocument(mongocxx::collection& collection, const bsoncxx::document::value& document)
+{
+	collection.insert_one(document.view());
+}
+
+// Delete a document from a given collection.
+void deleteDocument(mongocxx::collection& collection, const bsoncxx::document::value& document)
+{
+	collection.delete_one(document.view());
+}
+
+// Update the document with given key-value pair.
+void updateDocument(mongocxx::collection& collection, const string& key, const string& value, const string& newKey, const string& newValue)
+{
+	collection.update_one(bsoncxx::builder::stream::document{} << key << value << bsoncxx::builder::stream::finalize,
+		bsoncxx::builder::stream::document{} << "$set" << bsoncxx::builder::stream::open_document << newKey << newValue << bsoncxx::builder::stream::close_document << bsoncxx::builder::stream::finalize);
+}
+
+// Find the document with given key-value pair.
+void findDocument(mongocxx::collection& collection, const string& key, const string& value)
+{
+	// Create the query filter
+	auto filter = bsoncxx::builder::stream::document{} << key << value << bsoncxx::builder::stream::finalize;
+	
+	//Add query filter argument in find
+	auto cursor = collection.find({ filter });
+	
+	for (auto&& doc : cursor)
+	{
+		cout << bsoncxx::to_json(doc) << endl;
+	}
+}
+
+
+// ********************************************** I/O Methods **********************************************
+
+// Input student record.
+void inputStudentRecord(mongocxx::collection& collection)
+{
+	string name, rollNo, branch, year;
+
+	cout << "Enter name: ";
+	cin >> name;
+
+	cout << "Enter roll number: ";
+	cin >> rollNo;
+
+	cout << "Enter branch: ";
+	cin >> branch;
+
+	cout << "Enter year: ";
+	cin >> year;
+
+	insertDocument(collection, createDocument({ {"name", name}, {"rollNo", rollNo}, {"branch", branch}, {"year", year} }));
+}
+
+// Update student record.
+void updateStudentRecord(mongocxx::collection& collection)
+{
+	string rollNo, newBranch, newYear;
+
+	cout << "Enter roll number: ";
+	cin >> rollNo;
+
+	cout << "Enter new branch: ";
+	cin >> newBranch;
+
+	cout << "Enter new year: ";
+	cin >> newYear;
+
+	updateDocument(collection, "rollNo", rollNo, "branch", newBranch);
+	updateDocument(collection, "rollNo", rollNo, "year", newYear);
+}
+
+// Find student record.
+void findStudentRecord(mongocxx::collection& collection)
+{
+	string rollNo;
+
+	cout << "Enter roll number: ";
+	cin >> rollNo;
+
+	findDocument(collection, "rollNo", rollNo);
+}
+
+// Delete student record.
+void deleteStudentRecord(mongocxx::collection& collection)
+{
+	string rollNo;
+
+	cout << "Enter roll number: ";
+	cin >> rollNo;
+
+	deleteDocument(collection, createDocument({ {"rollNo", rollNo} }));
+}
+
+// Print student records.
+void printStudentRecords(mongocxx::collection& collection)
+{
+	printCollection(collection);
+}
+
+
+// ********************************************** Main **********************************************
+int main()
+{
+    if(mongoURI.to_string().empty())
+    {
+	cout << "URI is empty";
+	return 0;
+    }
+	
+    // Create an instance.
+    mongocxx::instance inst{};
+    
+    mongocxx::options::client client_options;
+    auto api = mongocxx::options::server_api{ mongocxx::options::server_api::version::k_version_1 };
+    client_options.server_api_opts(api);
+    mongocxx::client conn{ s_Cluster0_uri, client_options};
+    
+    const string dbName = "StudentRecords";
+    const string collName = "StudentCollection";
+    
+    auto dbs = getDatabases(conn);
+    // Check if database already exists.
+    if (!(std::find(dbs.begin(), dbs.end(), dbName) != dbs.end()))
+    {
+	// Create a new database & collection for students.
+	conn[dbName];
+     }
+     
+     auto studentDB = conn.database(dbName);
+     auto allCollections = studentDB.list_collection_names();
+     
+     // Check if collection already exists.
+     if (!(std::find(allCollections.begin(), allCollections.end(), collName) != allCollections.end()))
+     {
+	createCollection(studentDB, collName);
+     }
+     
+     auto studentCollection = studentDB.collection(collName);
+     
+     // Create a menu to for user interaction
+     int choice = -1;
+     
+     do while (choice != 0)
+     {
+	//system("cls");
+	cout << endl << "**************************************************************************************************************" << endl;
+		
+	cout << "Enter 1 to input student record" << endl;
+	cout << "Enter 2 to update student record" << endl;
+	cout << "Enter 3 to find student record" << endl;
+	cout << "Enter 4 to delete student record" << endl;
+	cout << "Enter 5 to print all student records" << endl;
+	cout << "Enter 0 to exit" << endl;
+	cout << "Enter Choice : "; 
+	cin >> choice;
+
+	cout << endl;
+		
+	switch (choice)
+	{
+		 case 1:
+			 inputStudentRecord(studentCollection);
+			 break;
+		 case 2:
+			 updateStudentRecord(studentCollection);
+			 break;
+		 case 3:
+			 findStudentRecord(studentCollection);
+			 break;
+		 case 4:
+			 deleteStudentRecord(studentCollection);
+			 break;
+		 case 5:
+			 printStudentRecords(studentCollection);
+			 break;
+		 case 0:
+			 break;
+		 default:
+			 cout << "Invalid choice" << endl;
+			 break;
+	}
+        
+      } while (choice != 0);
+      
+      return 0;
+}