如何模拟TryValidateModel

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;

public class UserModel
{
    [Required(ErrorMessage = "用户名不能为空")]
    public string Username { get; set; }

    [Required(ErrorMessage = "密码不能为空")]
    public string Password { get; set; }
}

public class ValidationTestContext : ValidationContext
{
    public ValidationTestContext(object instance) : base(instance)
    {
    }

    public override IServiceProvider GetServiceProvider()
    {
        // 返回一个自定义的 IServiceProvider 对象，用于提供所需的服务
        // 这里可以使用任何依赖注入容器或手动创建所需的服务实例
        // 在这个示例中，我们不涉及具体的服务实现，只是简单地返回 null
        return null;
    }
}

public class ValidationTestModelValidator : IObjectModelValidator
{
    public void Validate(ActionContext actionContext, ValidationStateDictionary validationState, string prefix, object model)
    {
        var validationContext = new ValidationTestContext(model);
        var validationResults = new List<ValidationResult>();

        Validator.TryValidateObject(model, validationContext, validationResults, true);

        foreach (var validationResult in validationResults)
        {
            validationState.Add(prefix, new ModelStateEntry()
            {
                ValidationState = ModelValidationState.Invalid,
                Errors = { new ModelError(validationResult.ErrorMessage) }
            });
        }
    }
}

public class Program
{
    public static void Main(string[] args)
    {
        var userModel = new UserModel()
        {
            Username = "",
            Password = "123456"
        };

        var validationState = new ValidationStateDictionary();
        var validator = new ValidationTestModelValidator();

        validator.Validate(null, validationState, "", userModel);

        if (validationState.IsValid)
        {
            Console.WriteLine("模型验证通过");
        }
        else
        {
            foreach (var entry in validationState)
            {
                foreach (var error in entry.Value.Errors)
                {
                    Console.WriteLine($"属性 {entry.Key}: {error.ErrorMessage}");
                }
            }
        }
    }
}