CODEWITHSUNDEEP
c#regex
user1137472
user1137472

Reputation: 345

Regular Expression stop crashing

Consider this code: 

[Required]
[RegularExpression(@"\d{2,2}/\d{2,2}/\d{4,4} \d{2,2}:\d{2,2}:\d{2,2}", 
ErrorMessage = "Wrong Syntax Entered, Needed:day/Month/Year Hour:Minutes:Seconds")]
public DateTime Posted { get; set; }

When I enter this value, my application crashes: 00/00/0000 00:00:00

Is there a way to stop this and make it more realistic? I'm wanting to allow the date so it only allows max 31 days or less up 1 and allows max months up 12 and min 1?

Upvotes: 0

Views: 494

Answers (4)

Manas
Manas

Reputation: 2542

Validating datatime with Regex will result in complex regex like 

^([0][1-9]||[1-2][0-9]||[3][0-1])/([0][1-9]||[1][1-2])/([1][0-9]{3}) ([0][1-9]||[1][0-2]):([0][1-9]||[1-5][0-9]):([0][1-9]||[1-5][0-9])$

But Still i doubt it may miss some edge cases.

If you are using MVC3, then the best way to Use Self validating model like follows,

public class TestModel:IValidatableObject
    {
        string MyDateTime{get;set;}

        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
        {
            List<ValidationResult> v = new List<ValidationResult>();
            DateTime dt = default(DateTime);
            DateTime.TryParseExact(MyDateTime, "dd/MM/yyyy HH:mm:ss", CultureInfo.InvariantCulture,DateTimeStyles.None,out dt);
            if (dt.Equals(default(DateTime)))
                v.Add(new ValidationResult("Invalid Date time"));
            return v;
        }
    }

Upvotes: 0

takepara
takepara

Reputation: 10433

Yet another, change FormatException message in ModelBinder(but going to far...).

DefaultModelBinder.GetValueInvalidResource is static method.I can not override this method. Because I create CustomModelBinder class and override SetProperty method.

[Required]
[AdditionalMetadata(
 "PropertyValueInvalid",
 "Wrong Syntax Entered, Needed:day/Month/Year Hour:Minutes:Seconds")]
public DateTime? Posted { get; set; }

And create custom ModelBinder

public class CustomModelBinder : DefaultModelBinder
{
    protected override void SetProperty(ControllerContext controllerContext, ModelBindingContext bindingContext, System.ComponentModel.PropertyDescriptor propertyDescriptor, object value)
    {
        base.SetProperty(controllerContext, bindingContext, propertyDescriptor, value);

        var propertyMetadata = bindingContext.PropertyMetadata[propertyDescriptor.Name];
        var invalidMessage = propertyMetadata.AdditionalValues.ContainsKey("PropertyValueInvalid")
                                 ? (string)propertyMetadata.AdditionalValues["PropertyValueInvalid"]
                                 : string.Empty;
        if (string.IsNullOrEmpty(invalidMessage))
        {
            return;
        }

        // code from DefaultModelBinder
        string fullPropertyKey = CreateSubPropertyName(bindingContext.ModelName, propertyDescriptor.Name);
        if (!bindingContext.ValueProvider.ContainsPrefix(fullPropertyKey))
        {
            return;
        }
        ModelState modelState = bindingContext.ModelState[fullPropertyKey];
        foreach (ModelError error in modelState.Errors.Where(err => String.IsNullOrEmpty(err.ErrorMessage) && err.Exception != null).ToList())
        {
            for (Exception exception = error.Exception; exception != null; exception = exception.InnerException)
            {
                if (exception is FormatException)
                {
                    string displayName = propertyMetadata.GetDisplayName();
                    string errorMessageTemplate = invalidMessage;
                    string errorMessage = String.Format(CultureInfo.CurrentCulture, errorMessageTemplate,
                                                        modelState.Value.AttemptedValue, displayName);
                    modelState.Errors.Remove(error);
                    modelState.Errors.Add(errorMessage);
                    break;
                }
            }
        }
    }
}

How about this?

Upvotes: 0

MRAB
MRAB

Reputation: 20654

A regex is the wrong way to validate dates and times. Use DateTime.TryParse instead.

EDIT:

Here's an example:

using System;
using System.Globalization;

...

bool valid;
DateTime dt;
valid = DateTime.TryParseExact(inputString, "dd/MM/yyyy HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None, out dt);

Upvotes: 2

David Hoerster
David Hoerster

Reputation: 28701

I agree with @MRAB that TryParse is probably easier to manage and maintain.

This SO question also tries to do what you're doing and they created a custom attribute (that derives from RegularExpressionAttribute) that seems to have solved his problem. Maybe it will help you.

Hope this helps.

Upvotes: 0

Related Questions