在AspNetCore中简单使用EFcore的一对多关系
我们将创建一个简单的示例。
准备两个模型：
- 待办事务列表（TodoList）
一个待办事务列表包含多个事务节点。
- 事务节点 （TransactionNode）
每个事务节点属于一个待办事务列表。
待办事务列表（TodoList）模型：
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| using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace TestEFc_IEQable_AspNetCore01x02
{
public class ToDoList
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
[MaxLength(50)]
public string? Id { get; set; }
public string? ListTitle { get; set; }
public string? ListDescription { get; set; }
public string? State { get; set; }
public List<TransactionNode>? TransactionNodes { get; set; }
}
}
|
事务节点（TransactionNode）模型：
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| using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace TestEFc_IEQable_AspNetCore01x02
{
public class TransactionNode
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
[MaxLength(50)]
public string? Id { get; set; }
public string? SerialNumber { get; set; }
public ToDoList? ToDoList { get; set; }
public string? State { get; set; }
public string? Content { get; set; }
}
}
|
配置数据库上下文（DbContext）：
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| using Microsoft.EntityFrameworkCore;
namespace TestEFc_IEQable_AspNetCore01x02
{
public class DateContext:DbContext
{
public DateContext(DbContextOptions<DateContext> options) : base(options) { }
public DbSet<ToDoList> ToDoListTable { get; set; }
public DbSet<TransactionNode> TransactionNodeTable { get; set; }
}
}
|
为模型类进行配置：
TodoList和TransactionNode之间的一对多关系可以通过导航属性进行配置。EF Core会自动识别这种关系。
ToDoList:
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| using Microsoft.EntityFrameworkCore;
namespace TestEFc_IEQable_AspNetCore01x02
{
public class ToDoListConfig: IEntityTypeConfiguration<ToDoList>
{
public void Configure(Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder<ToDoList> builder)
{
builder.ToTable("ToDoListTable");
builder.Property(a => a.ListTitle).HasMaxLength(50);
builder.Property(a => a.ListDescription).HasMaxLength(250);
}
}
}
|
TransactionNode:
注意这里的HasOne和WithMany的使用
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| using Microsoft.EntityFrameworkCore;
namespace TestEFc_IEQable_AspNetCore01x02
{
public class TransactionNodeConfig:IEntityTypeConfiguration<TransactionNode>
{
public void Configure(Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder<TransactionNode> builder)
{
builder.ToTable("TransactionNodeTable");
builder.HasOne<ToDoList>(a => a.ToDoList).WithMany(c => c.TransactionNodes).IsRequired();
builder.Property(a => a.Content).HasMaxLength(250);
}
}
}
|
program.cs中配置DbContext：
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| builder.Services.AddDbContext<DateContext>(options =>
options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"))
);
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在控制器中使用：
添加数据：
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| [HttpGet]
public async Task<ActionResult<string>> Test01_AddData()
{
var toDolist01 = new ToDoList()
{
Id = await _idGenService.NewGuidAsync(3),
ListTitle = "List02",
ListDescription = "List02_Description",
State = "0",
TransactionNodes = new List<TransactionNode>()
};
if (toDolist01.TransactionNodes == null)
{
return await Task.FromResult("toDolist01.TransactionNodes is null");
}
var transactionNode01 = new TransactionNode()
{
Id = await _idGenService.NewGuidAsync(3),
SerialNumber = "01",
State = "0",
Content = "Content02x01",
};
var transactionNode02 = new TransactionNode()
{
Id = await _idGenService.NewGuidAsync(3),
SerialNumber = "02",
State = "0",
Content = "Content02x02",
};
var transactionNode03 = new TransactionNode()
{
Id = await _idGenService.NewGuidAsync(3),
SerialNumber = "03",
State = "0",
Content = "Content02x03",
};
toDolist01.TransactionNodes.Add(transactionNode01);
toDolist01.TransactionNodes.Add(transactionNode02);
toDolist01.TransactionNodes.Add(transactionNode03);
await _dateContext.ToDoListTable.AddAsync(toDolist01);
await _dateContext.SaveChangesAsync();
return await Task.FromResult("ok");
}
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添加数据其实只要注意一下要初始化导航属性的集合就行了，比如上面的TransactionNodes。
查询数据：
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| [HttpGet]
public async Task<ActionResult<string>> Test01_GetData()
{
var toDoList = await _dateContext.ToDoListTable
.Include(t => t.TransactionNodes)
.FirstOrDefaultAsync(x => x.Id == "84c");
if (toDoList.TransactionNodes == null)
{
Console.WriteLine("toDoList.TransactionNodes is null");
return await Task.FromResult("toDoList.TransactionNodes is null");
}
_logger.LogInformation($"ToDoList Id:{toDoList.Id}, Title:{toDoList.ListTitle}, Description:{toDoList.ListDescription}, State:{toDoList.State}");
foreach (var item in toDoList.TransactionNodes)
{
_logger.LogInformation($"TransactionNode Id:{item.Id}, SerialNumber:{item.SerialNumber}, Content:{item.Content}, State:{item.State}");
}
return await Task.FromResult("ok");
}
|
在查询数据时，注意使用.Include方法来加载导航属性，以确保相关的事务节点也被加载。
查询数据运行截图：
