Customize ValidationAttribute - error message with entity ID (or some unique identifier) RRS feed

  • Question

  • I haven't been able to find an answer to this (or I'm just new to DataAnnotations):

    class Customer : Entity
       public string UniqueId { get; set; }
       public string LastName { get; set; }

    When I do validation, I want the error message to say:

    LastName is a required field for Customer: {UniqueId}

    Currently the error message does not identify the entity in anyway. Thus looking at logs, there is no way to figure this out.

    BTW, I'm using validation on POCOs for a windows service/console application.

    Monday, June 6, 2016 7:37 PM


  • Hi kplkumar,

    >>"Currently the error message does not identify the entity in anyway."

    We could customize error message in required attribute. Code below is for your reference.

    [Required(ErrorMessage = "LastName is a required field for Customer")]
    public string LastName { get; set; }

    You also could define a validate arrtibute which inherited from RequiredAttribute to customize error message.

    public string LastName { get; set; }
    public class CustomRequiredAttribute : System.ComponentModel.DataAnnotations.RequiredAttribute
        private string displayName;
        private string entityName;
        public CustomRequiredAttribute()
            this.ErrorMessage = "{0} is a required field for {1}";
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
            var attributes = validationContext.ObjectType.GetProperty(validationContext.MemberName).GetCustomAttributes(typeof(DisplayNameAttribute), true);
            if (attributes != null)
                this.displayName = (attributes[0] as DisplayNameAttribute).DisplayName;
                this.displayName = validationContext.DisplayName;
            this.entityName = validationContext.ObjectType.Name;
            return base.IsValid(value, validationContext);
        public override string FormatErrorMessage(string name)
            return string.Format(this.ErrorMessageString, displayName, entityName);
    Best Regards,
    Li Wang

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    • Proposed as answer by DotNet Wang Tuesday, June 7, 2016 5:44 AM
    • Marked as answer by DotNet Wang Wednesday, June 15, 2016 1:33 AM
    Tuesday, June 7, 2016 5:43 AM