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EF Core 提供程序

快速参考

此页面显示多个命令的提供商语法及其相关 API 文档的链接。

命令
语法
Configure a DBContext

API Documentation
Fundamentals
public class PlanetDbContext : DbContext
{
    public DbSet<Planet> Planets { get; init; }
    public static PlanetDbContext Create(IMongoDatabase database) =>
        new(new DbContextOptionsBuilder<PlanetDbContext>()
            .UseMongoDB(database.Client, database.DatabaseNamespace.DatabaseName)
            .Options);
    public PlanetDbContext(DbContextOptions options)
        : base(options)
    {
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Entity<Planet>().ToCollection("planets");
    }
}
Create an Instance of the DBContext

Fundamentals
// Replace the placeholder with your connection URI
var client = new MongoClient("<Your connection URI>");
var db = PlanetDbContext.Create(client.GetDatabase("sample_planets"));
db.Database.EnsureCreated();
var planet = db.Planets.FirstOrDefault(p => p.name == "Mercury");
Console.WriteLine(planet.name);
Find Multiple Entities

API Documentation
Fundamentals
var planets = db.Planets.Where(p => p.hasRings == true);
foreach (var p in planets)
{
   Console.WriteLine(p.name);
}
db.Planets.Add(new Planet()
{
    name = "Pluto",
    hasRings = false,
    orderFromSun = 9
});
db.SaveChanges();
Insert Multiple Entities

API Documentation
Fundamentals
var planets = new[]
{
    new Planet()
    {
        _id = ObjectId.GenerateNewId(),
        name = "Pluto",
        hasRings = false,
        orderFromSun = 9
    },
    new Planet()
    {
        _id = ObjectId.GenerateNewId(),
        name = "Scadrial",
        hasRings = false,
        orderFromSun = 10
    }
};
db.Planets.AddRange(planets);
db.SaveChanges();
var planet = db.Planets.FirstOrDefault(p => p.name == "Mercury");
planet.name = "Mercury the first planet";
db.SaveChanges();
Update Multiple Entities

API Documentation
Fundamentals
var planets = db.Planets.Where(p => p.orderFromSun > 0);
foreach (var p in planets)
{
    p.orderFromSun++;
}
db.SaveChanges();
var planet = db.Planets.FirstOrDefault(p => p.name == "Pluto");
db.Planets.Remove(planet);
db.SaveChanges();
Delete Multiple Entities

API Documentation
Fundamentals
var pluto = db.Planets.FirstOrDefault(p => p.name == "Pluto");
var scadrial = db.Planets.FirstOrDefault(p => p.name == "Scadrial");
var planets = new[] { pluto, scadrial };
db.Planets.RemoveRange(planets);
db.SaveChanges();
Specify the Order in Which to Retrieve Entities

API Documentation
Fundamentals
var planetList = db.Planets.OrderBy(p => p.orderFromSun);
foreach (var p in planetList)
{
    Console.WriteLine(p.name);
}
Specify Multiple Orderings to Retrieve Entities

API Documentation
Fundamentals
var planetList = db.Planets.OrderBy(o => o.hasRings).ThenBy(o => o.name);
foreach (var p in planetList)
{
    Console.WriteLine("Has rings: " + p.hasRings + ", Name: " + p.name);
}
Specify the Number of Entities to Retrieve

API Documentation
var planetList = db.Planets.Take(3);
foreach (var p in planetList)
{
    Console.WriteLine(p.name);
}
Specify the Number of Entities to Skip when Retrieving

API Documentation
var planetList = db.Planets.OrderBy(p => p.orderFromSun).Skip(5);
foreach (var p in planetList)
{
    Console.WriteLine(p.name);
}

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