Usando o LINQ para consultar o MongoDB em um aplicativo .NET Core

1
dotnet new console -o MongoExample
2
cd MongoExample
3
dotnet add package MongoDB.Driver

1
export ATLAS_URI="YOUR_ATLAS_URI_HERE"

1
using MongoDB.Bson;
2
using MongoDB.Driver;
3
using MongoDB.Driver.Linq;
4
5
MongoClientSettings settings = MongoClientSettings.FromConnectionString(
6
    Environment.GetEnvironmentVariable("ATLAS_URI")
7
);
8
9
settings.LinqProvider = LinqProvider.V3;
10
11
MongoClient client = new MongoClient(settings);

1
{
2
    "_id": ObjectId("573a1398f29313caabceb515"),
3
    "title": "Batman",
4
    "year": 1989,
5
    "rated": "PG-13",
6
    "runtime": 126,
7
    "plot": "The Dark Knight of Gotham City begins his war on crime with his first major enemy being the clownishly homicidal Joker.",
8
    "cast": [ "Michael Keaton", "Jack Nicholson", "Kim Basinger" ]
9
}

1
using MongoDB.Bson;
2
using MongoDB.Bson.Serialization.Attributes;
3
4
[BsonIgnoreExtraElements]
5
public class Movie {
6
7
    [BsonId]
8
    [BsonRepresentation(BsonType.ObjectId)]
9
    public string Id { get; set; }
10
11
    [BsonElement("title")]
12
    public string Title { get; set; } = null!;
13
14
    [BsonElement("year")]
15
    public int Year { get; set; }
16
17
    [BsonElement("runtime")]
18
    public int Runtime { get; set; }
19
20
    [BsonElement("plot")]
21
    [BsonIgnoreIfNull]
22
    public string Plot { get; set; } = null!;
23
24
    [BsonElement("cast")]
25
    [BsonIgnoreIfNull]
26
    public List<string> Cast { get; set; } = null!;
27
28
}

1
using MongoDB.Bson;
2
using MongoDB.Driver;
3
4
MongoClient client = new MongoClient(
5
    Environment.GetEnvironmentVariable("ATLAS_URI")
6
);
7
8
IMongoCollection<Movie> moviesCollection = client.GetDatabase("sample_mflix").GetCollection<Movie>("movies");
9
10
BsonDocument filter = new BsonDocument{
11
    { 
12
        "year", new BsonDocument{
13
            { "$gt", 1980 },
14
            { "$lt", 1990 }
15
        } 
16
    }
17
};
18
19
List<Movie> movies = moviesCollection.Find(filter).ToList();
20
21
foreach(Movie movie in movies) {
22
    Console.WriteLine($"{movie.Title}: {movie.Plot}");
23
}

1
using MongoDB.Driver;
2
using MongoDB.Driver.Linq;
3
4
MongoClientSettings settings = MongoClientSettings.FromConnectionString(
5
    Environment.GetEnvironmentVariable("ATLAS_URI")
6
);
7
8
settings.LinqProvider = LinqProvider.V3;
9
10
MongoClient client = new MongoClient(settings);
11
12
IMongoCollection<Movie> moviesCollection = client.GetDatabase("sample_mflix").GetCollection<Movie>("movies");
13
14
IMongoQueryable<Movie> results =
15
            from movie in moviesCollection.AsQueryable()
16
            where movie.Year > 1980 && movie.Year < 1990
17
            select movie;
18
19
foreach(Movie result in results) {
20
    Console.WriteLine("{0}: {1}", result.Title, result.Plot);
21
}

1
var results =
2
            from movie in moviesCollection.AsQueryable()
3
            where movie.Cast.Contains("Michael Keaton")
4
            select new { movie.Title, movie.Plot };

1
using MongoDB.Driver;
2
using MongoDB.Driver.Linq;
3
4
MongoClientSettings settings = MongoClientSettings.FromConnectionString(
5
    Environment.GetEnvironmentVariable("ATLAS_URI")
6
);
7
8
settings.LinqProvider = LinqProvider.V3;
9
10
MongoClient client = new MongoClient(settings);
11
12
IMongoCollection<Movie> moviesCollection = client.GetDatabase("sample_mflix").GetCollection<Movie>("movies");
13
14
var results = 
15
            from movie in moviesCollection.AsQueryable()
16
            where movie.Cast.Contains("Ryan Reynolds")
17
            from cast in movie.Cast
18
            where cast == "Ryan Reynolds"
19
            group movie by cast into g
20
            select new { Cast = g.Key, Sum = g.Sum(x => x.Runtime) };
21
22
foreach(var result in results) {
23
    Console.WriteLine("{0} appeared on screen for {1} minutes!", result.Cast, result.Sum);
24
}