我想要一种简单的方法来确保类中的某些属性包含值和/或在一个范围内(即:不超过50个字符)。我在How to validate Class properties?使用了问题和答案,遗憾的是我无法让它发挥作用。
为了测试它,我使用C#创建了一个非常简单的WinForm示例。即使我正在做同样的事情,但是当我应用不正确的值时,它永远不会抛出验证异常(即:将年龄设置为高于允许的限制)。
有人可以解释为什么它不会抛出异常吗?就好像该类不知道它应该使用所需的属性。
Form1.cs的
using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.ComponentModel.DataAnnotations;
namespace RequiredFieldsInClassExample {
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private void btnTest_Click(object sender, EventArgs e) {
try {
lstStatus.Items.Clear();
lstStatus.Items.Add("Creating list of people");
List<Person> CollectionOfPeople = new List<Person>();
lstStatus.Items.Add("Creating a good person");
Person Jeff = new Person();
Jeff.Age = 33;
Jeff.Firstname = "Jeff";
Jeff.Lastname = "Jefferson";
Jeff.GroupCode = "JJJ";
CollectionOfPeople.Add(Jeff);
lstStatus.Items.Add("Creating a bad person");
Person Tim = new Person();
Tim.Age = 444;
Tim.Firstname = "";
Tim.Lastname = "";
Tim.GroupCode = "";
CollectionOfPeople.Add(Tim);
lstStatus.Items.Add("Done");
} catch (ValidationException Exp) {
MessageBox.Show(this, Exp.Message, "Validation Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
} catch (Exception Exp) {
MessageBox.Show(this, Exp.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
}
}
Person.cs
using System.ComponentModel.DataAnnotations;
public class Person {
private int m_iAge = 1;
private string m_sFirstname = "Unknown";
private string m_sLastname = "";
private string m_sGroupCode = "AAA";
//[Required(ErrorMessage = "Age is a required field.")]
//[Range(1, 100, ErrorMessage = "A persons age must be between 1 and 100.")]
[Required, Range(1, 100)]
public int Age
{
get { return m_iAge; }
set { m_iAge = value; }
}
//[Required(ErrorMessage = "Firstname is a required field.")]
[Required]
public string Firstname
{
get { return m_sFirstname; }
set { m_sFirstname = value; }
}
public string Lastname
{
get { return m_sLastname; }
set { m_sLastname = value; }
}
//[StringLength(3)]
public string GroupCode
{
get { return m_sGroupCode; }
set { m_sGroupCode = value; }
}
}
答案 0 :(得分:3)
在Person类中添加一个新方法以执行验证。新的&#34;验证&#34;方法适用于所需的值,范围和字符串长度。
<强> Person.cs 强>
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Text;
public class Person {
private int m_iAge = 1;
private string m_sFirstname = "Unknown";
private string m_sLastname = "";
private string m_sGroupCode = "AAA";
[Required(ErrorMessage = "Age is a required field.")]
[Range(1, 100, ErrorMessage = "A persons age must be between 1 and 100.")]
public int Age
{
get { return m_iAge; }
set { m_iAge = value; }
}
[Required(ErrorMessage = "Firstname is a required field.")]
public string Firstname
{
get { return m_sFirstname; }
set { m_sFirstname = value; }
}
public string Lastname
{
get { return m_sLastname; }
set { m_sLastname = value; }
}
[StringLength(3, MinimumLength = 3)]
public string GroupCode
{
get { return m_sGroupCode; }
set { m_sGroupCode = value; }
}
public void Validate() {
ValidationContext context = new ValidationContext(this, serviceProvider: null, items: null);
List<ValidationResult> results = new List<ValidationResult>();
bool isValid = Validator.TryValidateObject(this, context, results, true);
if (isValid == false) {
StringBuilder sbrErrors = new StringBuilder();
foreach (var validationResult in results) {
sbrErrors.AppendLine(validationResult.ErrorMessage);
}
throw new ValidationException(sbrErrors.ToString());
}
}
}
回到表单后面的代码中,您只需要为每个类调用Validate方法。
<强> Form1.cs的强>
using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.ComponentModel.DataAnnotations;
namespace RequiredFieldsInClassExample {
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private void btnTest_Click(object sender, EventArgs e) {
try {
lstStatus.Items.Clear();
lstStatus.Items.Add("Creating list of people");
List<Person> CollectionOfPeople = new List<Person>();
lstStatus.Items.Add("Creating a good person");
Person Jeff = new Person();
Jeff.Age = 33;
Jeff.Firstname = "Jeff";
Jeff.Lastname = "Jefferson";
Jeff.GroupCode = "JJJ";
// LOOK! This line was added
Jeff.Validate();
CollectionOfPeople.Add(Jeff);
lstStatus.Items.Add("Creating a bad person");
Person Tim = new Person();
Tim.Age = 444;
Tim.Firstname = "";
Tim.Lastname = "";
Tim.GroupCode = "";
// LOOK! This line was added
Tim.Validate();
CollectionOfPeople.Add(Tim);
lstStatus.Items.Add("Done");
} catch (ValidationException Exp) {
MessageBox.Show(this, Exp.Message, "Validation Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
} catch (Exception Exp) {
MessageBox.Show(this, Exp.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
}
}
答案 1 :(得分:0)
我已经做了很长时间了,但是我会试一试。它认为您需要使用System.ComponentModel.DataAnnotations.Validator
类手动验证类。您还可以在需要验证的类上实现IValidatableObject
- 我喜欢这种方法。