Entity Framework -- 添加，删除，修改，关系依附，关系摘除，验证操作
数据库模型
这个基本上是浓缩 Jerry Tom博客的内容，作为参考http://www.cnblogs.com/mbailing/archive/2012/07/31/2616779.html
说明以后再写。
城市实体类
public partial class city
{
public int ID { get; set; }
[MaxLength(100)]
[RegularExpression(@"^[a-zA-Z''-'\s]{1,40}$")]
public string Name { get; set; }
public string CountryCode { get; set; }
public string District { get; set; }
public int Population { get; set; }
public virtual country country { get; set; }
//这个field临时添加，并没有在数据库中映射
[CustomValidation(typeof(BusinessValidations), "DescriptionRules")]
public string Description { get; set; }
}
国家实体类
public partial class country
{
public country()
{
this.cities = new List<city>();
}
public string Code { get; set; }
public string Name { get; set; }
public string Continent { get; set; }
public string Region { get; set; }
public float SurfaceArea { get; set; }
public Nullable<short> IndepYear { get; set; }
public int Population { get; set; }
public Nullable<float> LifeExpectancy { get; set; }
public Nullable<float> GNP { get; set; }
public Nullable<float> GNPOld { get; set; }
public string LocalName { get; set; }
public string GovernmentForm { get; set; }
public string HeadOfState { get; set; }
public Nullable<int> Capital { get; set; }
public string Code2 { get; set; }
public virtual ICollection<city> cities { get; set; }
}
自定义验证类
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
namespace EFEntity.Validation
{
public static class BusinessValidations
{
public static ValidationResult DescriptionRules(string value)
{
var errors = new System.Text.StringBuilder();
if (value != null)
{
var description = value as string;
if (description.Contains("!"))
{
errors.AppendLine("Description should not contain '!'.");
}
if (description.Contains(":)") || description.Contains(":("))
{
errors.AppendLine("Description should not contain emotions.");
}
}
if (errors.Length > 0)
return new ValidationResult(errors.ToString());
else
return ValidationResult.Success;
}
}
}
各种静态方法操作全在Controller.cs文件
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using EFEntity.Models;
namespace EFEntity
{
class Controller
{
/// <summary>
/// 添加一个实体
/// </summary>
/// <returns></returns>
public static int AddEntity()
{
using (var context = new worldContext())
{
var newCity = new city
{
CountryCode = "CHN",
District = "Guangdong",
Name = "珠海",
Population = 10000000
};
context.cities.Add(newCity);
return context.SaveChanges();
}
}
/// <summary>
/// 同时添加和修改实体
/// </summary>
/// <returns></returns>
public static int MakeMultipleChanges()
{
using (var context = new worldContext())
{
var niagaraFalls = new city
{
Name = "Niagara Falls",
CountryCode = "USA",
District = "California",
Population = 12232
};
context.cities.Add(niagaraFalls);
var query = (from d in context.cities
where d.Name == "广州"
select d).First();
query.Name = "惠州";
return context.SaveChanges();
}
}
/// <summary>
/// 删除一个实体
/// </summary>
/// <returns></returns>
public static int DeleteCity()
{
using (var context = new worldContext())
{
var oldCity = (from d in context.cities
where d.Name == "珠海"
select d).Single();
context.cities.Remove(oldCity);
return context.SaveChanges();
}
}
/// <summary>
/// 级联删除一个实体(国家)和它相关联的从表实体（城市）
/// </summary>
/// <returns></returns>
public static int DeleteUsaAndCities()
{
using (var context = new worldContext())
{
var countryUSA = (from d in context.countries
where d.Name == "United States"
select d).Single();
context.Entry(countryUSA).Collection(d => d.cities).Load();
context.countries.Remove(countryUSA);
return context.SaveChanges();
}
}
/// <summary>
/// 找到返回一个实体，找不到添加并返回一个实体
/// </summary>
public static void FindOrAddCity()
{
using (var context = new worldContext())
{
var newCity = context.cities.FirstOrDefault(p => p.Name == "湛江");
if (newCity == null)
{
newCity = context.cities.Add(new city
{
Name = "湛江",
CountryCode = "CHN",
District = "Guangdong",
Population = 100
});
context.SaveChanges();
}
Console.WriteLine("增加或找到的城市为：" + newCity.Name);
}
}
/// <summary>
/// 创建从表实体，并依附到主表实体，建立关联。
/// </summary>
/// <returns></returns>
public static int NewRelationData()
{
using (var context = new worldContext())
{
var newcity = new city
{
Name = "随便什么城市",
CountryCode = "CHN", //这个属性值后来还是变成为ZWE，
//说明我们在Country加载后覆盖了这个值。
District = "Guangdong",
Population = 1231232
};
context.cities.Add(newcity);
var countryChina = (from d in context.countries
where d.Code == "ZWE"
select d).Single();
countryChina.cities.Add(newcity);
return context.SaveChanges();
}
}
/// <summary>
/// 修改从表实体的依附关系
/// </summary>
/// <returns></returns>
public static int ChangeRelationData()
{
using (var context = new worldContext())
{
var oldCity = (from c in context.cities
where c.Name == "湛江"
select c).Single();
var oldCountry = (from d in context.countries
where d.Code == "ZWE"
select d).Single();
oldCity.country = oldCountry;
return context.SaveChanges();
}
}
/// <summary>
/// 检查修改状态
/// </summary>
public static void ManualDetectChanges()
{
using (var context = new worldContext())
{
context.Configuration.AutoDetectChangesEnabled = false;
var countryAFG = (from d in context.countries
where d.Name == "Afghanistan"
select d).Single();
countryAFG.SurfaceArea = 1000000;
Console.WriteLine("Before DetectChanges: {0}", context.Entry(countryAFG).State);
context.ChangeTracker.DetectChanges();
Console.WriteLine("After DetectChanges: {0}", context.Entry(countryAFG).State);
}
}
/// <summary>
/// 验证通用方法
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="input"></param>
public static void ConsoleValidateResult<T>(T input) where T : class
{
using (var context = new worldContext())
{
if (context.Entry(input).GetValidationResult().IsValid)
{
Console.WriteLine("----Valid 验证通过!");
}
else
{
Console.WriteLine("----Invalid 验证不通过！");
}
}
}
/// <summary>
/// 验证实体
/// </summary>
public static void ValidateCity()
{
//-------------------------------------
Console.WriteLine("\n验证最大长度");
ConsoleValidateResult<city>(
new city
{
Name = "3412ieiorjteiwjlkrj0943u5094tiroejiktjfgkjfdklsjgdsfddfgfdgfdlksdfs",
CountryCode = "CHN",
District = "Guangdong",
Population = 122
});
//-------------------------------------
Console.WriteLine("\n验证正则表达式");
ConsoleValidateResult<city>(
new city
{
Name = "BeiJingCity",
CountryCode = "CHN",
District = "直辖市",
Population = 100
});
//-------------------------------------
Console.WriteLine("\n验证自定义的规则，这里是Description不能有某些字符串");
ConsoleValidateResult<city>(
new city
{
Name = "Guangzhou", //这里不能是汉字，要不然通不过正则表达式验证
CountryCode = "CHN",
District = "Guangdong",
Population = 100,
Description = "This is the description."
});
}
/// <summary>
/// 于请求中验证属性（Validating Individual Properties on Demand)
/// </summary>
public static void ValidatePropertyOnDemand()
{
var cityItem = new city
{
Name = "Beijing",
CountryCode = "CHN",
District = "直辖市",
Population = 100,
Description = "我爱北京天安门，Shit!"
};
using (var context = new worldContext())
{
var errors = context.Entry(cityItem).Property(p => p.Description).GetValidationErrors();
Console.WriteLine();
Console.WriteLine("#Description 验证错误; {0}",errors.Count());
}
}
}
}
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