.net使用EF操作SQLite (codefirst vs2015)

配置config

连接字符串
 
   
 

支撑程序

   
     
     
     

   

编写model类

    using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;

namespace safetodelete_efSqLite_ConsoleApplication1
{
    [Table("employee")]
    class Employee
    {
        [Key]
        public String employeeId { get; set; }
        public String name { get; set; }
    }
}

编写context类

    using System.Data.Entity;
using System.Data.Common;
using System.Data.SQLite.EF6;
using SQLite.CodeFirst;

namespace safetodelete_efSqLite_ConsoleApplication1
{
    class EmployeeContext : DbContext
    {
        public EmployeeContext() : base("sqliteconn") { }

        public EmployeeContext(DbConnection sqliteCon) : base("sqliteconn")
        {
            this.sqliteCon = sqliteCon;
        }
        public DbSet employees { get; set; }
        static string dbPath = @"data source=sqLiteTestDB.db";
        private DbConnection sqliteCon;
        public static EmployeeContext Instance
        {
            get
            {
                DbConnection sqliteCon = SQLiteProviderFactory.Instance.CreateConnection();
                sqliteCon.ConnectionString = dbPath;
                return new EmployeeContext(sqliteCon);
            }
        }      
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //如果不存在数据库，则创建
            Database.SetInitializer(new SqliteCreateDatabaseIfNotExists(modelBuilder));
        }
    }
}    

测试程序

           static void Main(string[] args)
        {

            Employee e1 = new Employee();
            e1.employeeId = Guid.NewGuid().ToString();
            e1.name = "xiaoming";

            EmployeeContext ec = new EmployeeContext();
            ec.employees.Add(e1);
            ec.SaveChanges();     

            Console.WriteLine("hello world");
            Console.ReadKey();            

        }

 

2019-03-28

sqlite只能在一个Context类中创建、更新数据库，也就是说如果一个项目中存在多个Context和Model类时codefirst也只能创建或者更新一个Context以及model;

解决方法：

class EmployeeContext : DbContext
    {
        public EmployeeContext() : base("employeedbconn") { }
        public DbSet employees { get; set; }
        public DbSet checkRecords { get; set; }


        public EmployeeContext(DbConnection sqliteCon) : base("employeedbconn")
        {
            this.sqliteCon = sqliteCon;
        }
        static string dbPath = @"data source=employeedb.db";
        private DbConnection sqliteCon;
        public static EmployeeContext Instance
        {
            get
            {
                DbConnection sqliteCon = SQLiteProviderFactory.Instance.CreateConnection();
                sqliteCon.ConnectionString = dbPath;
                return new EmployeeContext(sqliteCon);
            }
        }
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //如果不存在数据库，则创建
           
            

      Database.SetInitializer(new SqliteCreateDatabaseIfNotExists(modelBuilder));
       //     Database.SetInitializer(new SqliteCreateDatabaseIfNotExists(modelBuilder));

        }


    }

 

如上所示：

可以在一个Context类中包含其它需要CodeFirst的Model类。这样就可以在创建或者初始化开始时一并创建所有Model。

照此机制创建一个专门用来创建和更新表结构的生成类Context把需要的Model全都放里，这样其它的Context类就不用在进行更新表结构的操作。