.Net Core中使用MongoDB

冷暖吱吱 發表於 2020-8-2 16:48:00

MongoDB 是由C++语言编写的，是一个基于分布式且面向文档存储的开源数据库系统。
下载地址：
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<pre>https://www.mongodb.com/download-center/community</pre>
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在.Net Core中使用需要引入核心包 MongoDB.Driver
添加数据：
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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 = "暂无";
//添加一条数据
student.InsertOne(data);</pre>
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在图形化界面中查看一下
<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802145400844-124027726.png" alt="" loading="lazy">
<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802145435120-1154519711.png" alt="" loading="lazy">
 Mongodb默认用id做主键,因此不会显式的指定id是主键。Mongdb中没有内置"自增字段",可以把id声明为ObjectId类型,这样插入以后就自动给字段赋值。
例如，建一个类：
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<pre>public class School
{
public ObjectId id { get; set; }
public string name { get; set; }
public string address { get; set; }
} //需引入命名空间 using MongoDB.Bson;</pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802150651076-1572692546.png" alt="" loading="lazy">
<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802150759459-49698672.png" alt="" loading="lazy">
 当然School对象之后多加或者去掉一个字段都行。Mongodb是用Json保存的,因此也可以直接用Json格式插入,可用BsonDocument对象作为泛型对象。
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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学校',address:'xxx路xx号',remarks:'暂无！'}";
BsonDocument bsons = BsonDocument.Parse(json);</pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802152107871-1866451096.png" alt="" loading="lazy">
 学生和学校是有对应关系的,我们可以添加有嵌套关系类型的对象
<div class="cnblogs_code">
<pre>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; }
}</pre>
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<div class="cnblogs_code">
<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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 = "暂无";
School school = new School();
school.name = "xxxSchool";
school.address = "xxxAddress";
student1.School = school;
student.InsertOne(student1);
 </pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802153305150-802214181.png" alt="" loading="lazy">
 数据查询：
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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:大于
var result = student.Find(data).ToList();</pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802154725796-66020882.png" alt="" loading="lazy">
 我们安装的NuGet包是支持Lamda表达式的,可用条件表达式来查找数据
<div class="cnblogs_code">
<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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();</pre>
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分页查询：
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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();</pre>
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数据更新：
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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); </pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802163028912-618262289.png" alt="" loading="lazy">
 数据删除：
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<pre>//与Mongodb建立连接
MongoClient client = new MongoClient("mongodb://127.0.0.1");
//获得数据库,没有则自动创建
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);//只删除一个</pre>
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<img src="https://img2020.cnblogs.com/blog/1677460/202008/1677460-20200802163332491-1313543180.png" alt="" loading="lazy">
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<pre>MongoDB中文网:https://www.mongodb.org.cn</pre>
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来源：https://www.cnblogs.com/zhangnever/p/13419532.html

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.Net Core中使用MongoDB