Entity Framework DbContext Validation API

Dec 18, 2014

6 mins read

先建一張資料表，並加上幾個Attribute當例子

namespace ConsoleApplication1.Models
{
    using System;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;
[Table("Table1")]
public class Table1
{
    [Key]
    public int Table1Id { get; set; }

    [Required]
    [StringLength(10, MinimumLength = 2)]
    public string C1 { get; set; }

    [Range(10, 20)]
    public int C2 { get; set; }

    public DateTime D1 { get; set; }

    public DateTime D2 { get; set; }
}

}

針對屬性驗證

namespace ConsoleApplication1
{
    using ConsoleApplication1.Models;
    using System;
    using System.Data.Entity;
class Program
{
    static void Main(string[] args)
    {
        Database.SetInitializer(new DropCreateDatabaseAlways&lt;DemoContext&gt;());
        using (DemoContext db = new DemoContext())
        {
            db.Database.Initialize(false);

            Table1 table1 = new Table1
            {
                C1 = "a",
                C2 = 1,
                D1 = DateTime.Now,
                D2 = DateTime.Now.AddDays(-1)
            };

            foreach (var item in db.Entry(table1).Property(x =&gt; x.C1).GetValidationErrors())
            {
                Console.WriteLine(item.ErrorMessage);
            }

            foreach (var item in db.Entry(table1).Property(x =&gt; x.C2).GetValidationErrors())
            {
                Console.WriteLine(item.ErrorMessage);
            }
        }
    }
}

}

針對實體驗證

namespace ConsoleApplication1
{
    using ConsoleApplication1.Models;
    using System;
    using System.Data.Entity;
class Program
{
    static void Main(string[] args)
    {
        Database.SetInitializer(new DropCreateDatabaseAlways&lt;DemoContext&gt;());
        using (DemoContext db = new DemoContext())
        {
            db.Database.Initialize(false);

            Table1 table1 = new Table1
            {
                C1 = "a",
                C2 = 1,
                D1 = DateTime.Now,
                D2 = DateTime.Now.AddDays(-1)
            };

            foreach (var item in db.Entry(table1).GetValidationResult().ValidationErrors)
            {
                Console.WriteLine(item.ErrorMessage);
            }
        }
    }
}

}

針對DbContext驗證

namespace ConsoleApplication1
{
    using ConsoleApplication1.Models;
    using System;
    using System.Data.Entity;
class Program
{
    static void Main(string[] args)
    {
        Database.SetInitializer(new DropCreateDatabaseAlways&lt;DemoContext&gt;());
        using (DemoContext db = new DemoContext())
        {
            db.Database.Initialize(false);

            Table1 table1 = new Table1
            {
                C1 = "a",
                C2 = 1,
                D1 = DateTime.Now,
                D2 = DateTime.Now.AddDays(-1)
            };

            db.Table1.Add(table1);
            foreach (var result in db.GetValidationErrors())
            {
                foreach (var item in result.ValidationErrors)
                {
                    Console.WriteLine(item.ErrorMessage);
                }
            }
        }
    }
}

}

輸出的畫面如下

[![](http://3.bp.blogspot.com/-609pUnv8j8U/VJJ_9ch4SYI/AAAAAAAAB0U/QV7isgRzPNI/s1600/01.png)](http://3.bp.blogspot.com/-609pUnv8j8U/VJJ_9ch4SYI/AAAAAAAAB0U/QV7isgRzPNI/s1600/01.png)

自定義驗證屬性規則，加入一個靜態類別，用來放自定義的驗證規則

namespace ConsoleApplication1.Models
{
    using System.ComponentModel.DataAnnotations;
public static class MyCustomRule
{
    public static ValidationResult MyStringRule(string value)
    {
        if (value == "a")
        {
            return new ValidationResult("字串不可為a");
        }
        else
        {
            return ValidationResult.Success;
        }
    }

    public static ValidationResult MyIntRule(int value)
    {
        if (value == 1)
        {
            return new ValidationResult("數字不可為1");
        }
        else
        {
            return ValidationResult.Success;
        }
    }
}

}

在屬性上加入自定義的驗證規則

namespace ConsoleApplication1.Models
{
    using System;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;
[Table("Table1")]
public class Table1
{
    [Key]
    public int Table1Id { get; set; }

    [Required]
    [StringLength(10, MinimumLength = 2)]
    [CustomValidation(typeof(MyCustomRule), "MyStringRule")]
    public string C1 { get; set; }

    [Range(10, 20)]
    [CustomValidation(typeof(MyCustomRule), "MyIntRule")]
    public int C2 { get; set; }

    public DateTime D1 { get; set; }

    public DateTime D2 { get; set; }
}

}

驗證資料的時後，就會包含自定義的規則

[![](http://2.bp.blogspot.com/-WL8Il-n32Jk/VJKACUZv-DI/AAAAAAAAB0c/XTMlR3RudAY/s1600/02.png)](http://2.bp.blogspot.com/-WL8Il-n32Jk/VJKACUZv-DI/AAAAAAAAB0c/XTMlR3RudAY/s1600/02.png)

自定義驗證實體規則，在實體上實作IValidatableObject介面

namespace ConsoleApplication1.Models
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;
    using System.ComponentModel.DataAnnotations.Schema;
[Table("Table1")]
public class Table1 : IValidatableObject
{
    [Key]
    public int Table1Id { get; set; }

    [Required]
    // [StringLength(10, MinimumLength = 2)]
    public string C1 { get; set; }

    // [Range(10, 20)]
    public int C2 { get; set; }

    public DateTime D1 { get; set; }

    public DateTime D2 { get; set; }

    public IEnumerable&lt;ValidationResult&gt; Validate(ValidationContext validationContext)
    {
        if (this.C1 == "a")
        {
            yield return new ValidationResult("字串不可為a");
        }

        if (this.C2 == 1)
        {
            yield return new ValidationResult("數字不可為1");
        }

        if (this.D1 &gt;= this.D2)
        {
            yield return new ValidationResult("d1不能大於d2");
        }
    }
}

}

自定義驗證DbContext規則，覆寫ValidateEntity函式

namespace ConsoleApplication1.Models
{
    using System.Collections.Generic;
    using System.Data.Entity;
    using System.Data.Entity.Infrastructure;
    using System.Data.Entity.Validation;
public class DemoContext : DbContext
{
    public DbSet&lt;Table1&gt; Table1 { get; set; }
    public DbSet&lt;Table2&gt; Table2 { get; set; }

    protected override DbEntityValidationResult ValidateEntity(DbEntityEntry entityEntry, IDictionary&lt;object, object&gt; items)
    {
        var result = base.ValidateEntity(entityEntry, items);
        var table1 = entityEntry.Entity as Table1;
        if (table1 != null)
        {
            if (table1.C1 == "a")
            {
                result.ValidationErrors.Add(new DbValidationError("C1", "字串不可為a"));
            }

            if (table1.C2 == 1)
            {
                result.ValidationErrors.Add(new DbValidationError("C2", "數字不可為1"));
            }

            if (table1.D1 &gt;= table1.D2)
            {
                result.ValidationErrors.Add(new DbValidationError("D1", "d1不能大於d2"));
            }
        }

        return result;
    }
}

}

輸出的結果如下

[![](http://4.bp.blogspot.com/-qQ9gSatBC6c/VJKGMywO5NI/AAAAAAAAB0s/rEVP1WCzPyg/s1600/03.png)](http://4.bp.blogspot.com/-qQ9gSatBC6c/VJKGMywO5NI/AAAAAAAAB0s/rEVP1WCzPyg/s1600/03.png)