LINQ 2 DB 动态插入表

Posted 2023-04-12

【中文标题】LINQ 2 DB 动态插入表

【英文标题】：LINQ 2 DB insert dynamic into table

【发布时间】：2020-09-17 08:13:17

【问题描述】：

我想使用动态以便能够选择要定义的列以及我想让数据库设置DEFAULT 值的列。 有没有办法将dynamic 插入表中并返回Id？

我在 DataConnection 和 ITable<> 上尝试了各种重载，但我唯一能实现的结果是获取受影响的行数。

这是我的代码：

人员表架构

CREATE TABLE [dbo].[Person] (
    [Id]        BIGINT       IDENTITY (1, 1) NOT NULL,
    [Name]      VARCHAR (50) NOT NULL,
    [Surname]   VARCHAR (50) NOT NULL,
    [BirthDate] DATE         DEFAULT (getdate()) NOT NULL
);

.NET Core 控制台应用程序

public class Person

    public uint Id  get; set; 
    public string Name  get; set; 
    public string Surname  get; set; 
    public DateTime BirthDate  get; set; 

public class PeopleDataConnection : DataConnection

    public PeopleDataConnection(string connectionString)
        : base(ProviderName.SqlServer, connectionString)
     

    public ITable<Person> People => this.GetTable<Person>();

class Program

    static async Task Main(string[] args)
    
        await using (var db = new PeopleDataConnection("Server=DESKTOP-I41VSUN;integrated Security=SSPI;Database=MotoGPRiders;"))
        
            var dynamicPerson = new  Name = "Cal", Surname = "Crutchlow", BirthDate = new DateTime(1985, 10, 29) ;
            var person_without_id = new Person  Name = "Valentino", Surname = "Rossi", BirthDate = new DateTime(1979, 2, 16) ;

            var affectedRowsCount = await db.InsertAsync(dynamicPerson, nameof(Person));
            affectedRowsCount = await db.People
                .Value(x => x.Name, person_without_id.Name)
                .Value(x => x.Surname, person_without_id.Surname)
                .Value(x => x.BirthDate, person_without_id.BirthDate)
                .InsertAsync();
        
        Console.ReadLine();
    

第一个插入完成工作但不能返回Id，第二个让我选择列但不是动态的。

有没有办法做到这一点？ 提前致谢！

【参考方案1】：

您可以通过InsertWithInt64IdentityAsync 函数检索身份值。这种插入有很多重载：

var insertedId = await db.People
            .Value(x => x.Name, person_without_id.Name)
            .Value(x => x.Surname, person_without_id.Surname)
            .Value(x => x.BirthDate, person_without_id.BirthDate)
            .InsertWithInt64IdentityAsync();

您还可以过滤掉必须通过具有columnFilter 参数的重载插入的属性：

var insertedId = await db.InsertAsync(person, 
    e => e.MemberName.In("Name", "Surname", "BirthDate"));

对于具有匿名类的变体，您必须创建自己的函数，该函数使用 Value.Value.Value + InsertWithInt64IdentityAsync 调用通过反射生成调用：

public static class DynamicExtensions

    public static IValueInsertable<T> GenerateInsertable<T>(this ITable<T> table, object obj)
    
        var dynamicAccessor = TypeAccessor.GetAccessor(obj.GetType());
        var accessor = TypeAccessor.GetAccessor<T>();
        var objValue = Expression.Constant(obj);
        IValueInsertable<T> insertable = null;
        foreach (var dynamicMember in dynamicAccessor.Members)
        
            var found = accessor.Members.Find(m => m.Name == dynamicMember.Name);
            if (found == null)
                continue;
            var sourceParam = Expression.Parameter(typeof(T), "e");
            var property = Expression.Lambda(Expression.MakeMemberAccess(sourceParam, found.MemberInfo),
                sourceParam);
            Expression value = Expression.MakeMemberAccess(objValue, dynamicMember.MemberInfo);
            if (value.Type != found.Type)
                value = Expression.Convert(value, found.Type);
            value = Expression.Lambda(value);

            if (insertable == null)
            
                var method = Methods.LinqToDB.Insert.T.ValueExpression.MakeGenericMethod(typeof(T), found.Type);
                insertable = (IValueInsertable<T>)method.Invoke(null, new object[]  table, property, value );
            
            else
            
                var method = Methods.LinqToDB.Insert.VI.ValueExpression.MakeGenericMethod(typeof(T), found.Type);
                insertable = (IValueInsertable<T>)method.Invoke(null, new object[]  insertable, property, value );
            
        

        return insertable;
    

    public static long? InsertWithIdentityDynamic<T>(this ITable<T> table, object obj)
    
        var insertable = GenerateInsertable(table, obj);
        if (insertable == null)
            return null;
        
        return insertable.InsertWithInt64Identity();
    

    public static async Task<long?> InsertWithIdentityDynamicAsync<T>(this ITable<T> table, object obj, CancellationToken cancellationToken = default)
    
        var insertable = GenerateInsertable(table, obj);
        if (insertable == null)
            return null;

        return await insertable.InsertWithInt64IdentityAsync(cancellationToken);
    

及用法：

var insertedId = await db.GetTable<Person>()
    .InsertWithIdentityDynamicAsync(dynamicPerson);