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kenwalger/Program.cs

Last active Dec 18, 2020
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C# and MongoDB: Read Operation Quick Start
using System;
using MongoDB.Bson;
using MongoDB.Driver;
namespace MongoDBCRUDExample
{
class Program
{
static void Main(string[] args)
{
MongoClient dbClient = new MongoClient("mongodb+srv://test_user:MongoDBR0cks@demodata-uymyo.mongodb.net/test?retryWrites=true&w=majority");
var dbList = dbClient.ListDatabases().ToList();
Console.WriteLine("The list of databases on this server is: ");
foreach (var db in dbList)
{
Console.WriteLine(db);
}
Console.WriteLine("Connecting to sample_training.grades");
var database = dbClient.GetDatabase("sample_training");
var collection = database.GetCollection<BsonDocument>("grades");
// Define a new student for the grade book.
var document = new BsonDocument
{
{ "student_id", 10000 },
{ "scores", new BsonArray
{
new BsonDocument{ {"type", "exam"}, {"score", 88.12334193287023 } },
new BsonDocument{ {"type", "quiz"}, {"score", 74.92381029342834 } },
new BsonDocument{ {"type", "homework"}, {"score", 89.97929384290324 } },
new BsonDocument{ {"type", "homework"}, {"score", 82.12931030513218 } }
}
},
{ "class_id", 480}
};
// *********************************
// Create Operations
// *********************************
// Insert the new student grade records into the database.
Console.WriteLine("Inserting Document");
collection.InsertOne(document);
Console.WriteLine("Document Inserted.\n");
// *********************************
// Read Operations
// *********************************
// Find first record in the database
var firstDocument = collection.Find(new BsonDocument()).FirstOrDefault();
Console.WriteLine("\n**********\n");
Console.WriteLine(firstDocument.ToString());
// Find a specific document with a filter
var filter = Builders<BsonDocument>.Filter.Eq("student_id", 10000);
var studentDocument = collection.Find(filter).FirstOrDefault();
Console.WriteLine("\n**********\n");
Console.WriteLine(studentDocument.ToString());
// Find all documents with an exam score equal or above 95 as a list
//var highExamScoreFilter = Builders<BsonDocument>
// .Filter.Eq("scores.type", "exam") & Builders<BsonDocument>.Filter.Gte("score", 95);
var highExamScoreFilter = Builders<BsonDocument>.Filter
.ElemMatch<BsonValue>("scores",
new BsonDocument { { "type", "exam" },
{ "score", new BsonDocument { { "$gte", 95 } } }
});
var highExamScores = collection.Find(highExamScoreFilter).ToList();
Console.WriteLine("\n**********\n");
Console.WriteLine(highExamScores);
// Find all documents with an exam score equal
// or above 95 as an iterable
var cursor = collection.Find(highExamScoreFilter).ToCursor();
Console.WriteLine("\n**********\n");
Console.WriteLine("\nHigh Scores Iterable\n");
Console.WriteLine("\n**********\n");
foreach (var cursorDocument in cursor.ToEnumerable())
{
Console.WriteLine(cursorDocument);
}
// Sort the exam scores by student_id
var sort = Builders<BsonDocument>.Sort.Descending("student_id");
var highestScore = collection.Find(highExamScoreFilter).Sort(sort).First();
Console.WriteLine("\n**********\n");
Console.WriteLine("\nHigh Score\n");
Console.WriteLine("\n**********\n");
Console.WriteLine(highestScore);
}
}
}
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