.Net Core中使用MongoDB

MongoDB 是由C++語言編寫的，是一個基於分佈式且面向文檔存儲的開源數據庫系統。

下載地址：

https://www.mongodb.com/download-center/community

在.Net Core中使用需要引入核心包 MongoDB.Driver

添加數據：

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var data = new Student();
data.id = 1;
data.name = "江北";
data.age = 22;
data.remarks = "暫無";
//添加一條數據
student.InsertOne(data);

在圖形化界面中查看一下

 Mongodb默認用id做主鍵,因此不會顯式的指定id是主鍵。Mongdb中沒有內置"自增字段",可以把id聲明爲ObjectId類型,這樣插入以後就自動給字段賦值。

例如，建一個類：

public class School
{
    public ObjectId id { get; set; }
    public string name { get; set; }
    public string address { get; set; }
}
//需引入命名空間 using MongoDB.Bson;

 當然School對象之後多加或者去掉一個字段都行。Mongodb是用Json保存的,因此也可以直接用Json格式插入,可用BsonDocument對象作爲泛型對象。

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<BsonDocument> document = db.GetCollection<BsonDocument>("School");
db.GetCollection<BsonDocument>("School");
var json = "{id:1,name:'xx學校',address:'xxx路xx號',remarks:'暫無！'}";
BsonDocument bsons = BsonDocument.Parse(json);

 學生和學校是有對應關係的,我們可以添加有嵌套關係類型的對象

public class Student
{
    public int id { get; set; }
    public string name { get; set; }
    public int age { get; set; }
    public string remarks { get; set; }
    public School School { get; set; }
}

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
Student student1 = new Student();
student1.id = 2;
student1.name = "北晚舟";
student1.age = 22;
student1.remarks = "暫無";
School school = new School();
school.name = "xxxSchool";
school.address = "xxxAddress";
student1.School = school;
student.InsertOne(student1);

 數據查詢：

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var data = Builders<Student>.Filter.Gt(m => m.age, 21);//Gt:大於
var result = student.Find(data).ToList();

 我們安裝的NuGet包是支持Lamda表達式的,可用條件表達式來查找數據

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var data = Builders<Student>.Filter.Where(m => m.age > 21 && m.name.Contains("江"));
var result = student.Find(data).ToList();

分頁查詢：

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var filter = Builders<Student>.Filter.Where(m => m.age > 21);
FindOptions<Student, Student> findOpt = new FindOptions<Student, Student>();
findOpt.Limit = 2;
findOpt.Skip = 1;
findOpt.Sort = Builders<Student>.Sort.Ascending(m => m.age).Descending(m => m.name);
var result = (student.FindAsync(filter, findOpt).Result).ToList();

數據更新：

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var filter = Builders<Student>.Filter.Where(m => m.age > 21);
var update = Builders<Student>.Update.Set(m => m.name, "皮卡丘");
//update Student set name="皮卡丘" where age>21
student.UpdateMany(filter, update); 

 數據刪除：

//與Mongodb建立連接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//獲得數據庫,沒有則自動創建
IMongoDatabase db = client.GetDatabase("db1");
//拿到集合(表)
IMongoCollection<Student> student = db.GetCollection<Student>("Student");
var filter = Builders<Student>.Filter.Where(m => m.age > 21);
//delete from Student where age>21
//student.DeleteMany(filter);
student.DeleteOne(filter);//只刪除一個

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