TagBoxValidateBy Enum

Lists values that define how a TagBox located within the standard EditForm is validated.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v20.2.dll

NuGet Package: DevExpress.Blazor

Declaration

public enum TagBoxValidateBy

Members

Name	Description
Auto	If the Tags property is specified, the editor’s tags are validated. If the Values property is specified, the editor’s values are validated.
Tags	The editor’s tags are validated.
Values	The editor’s values are validated.

Related API Members

The following properties accept/return TagBoxValidateBy values:

• DxTagBox<TData, TValue>.ValidateBy

Remarks

The DevExpress UI components support the Blazor’s form validation. For more information, refer to the ASP.NET Core Blazor forms and validation MSDN article.

The code below uses the ValidateBy property to validate email addresses (custom tags) specified in the TagBox. In this example the following validation settings are specified:

• the ValidateBy property is set to TagBoxValidateBy.Tags;
• the Tags property’s bound field is marked with the Required and custom data annotation attributes that validate email formats.

After a user types an email address, the edit box is underlined in red or green: red indicates the editor contains an invalid tag(s) or is empty; green indicates the tags are valid.

Razor

<EditForm Model="@recipients" OnValidSubmit="@HandleValidSubmit" OnInvalidSubmit="@HandleInvalidSubmit">
    <DataAnnotationsValidator />
    <p>
        <label for="emails">Recipients:</label>
        <DxTagBox Id="emails"
                  NullText="Select email recipients"
                  Data="@Emails.DataSource"
                  TData="string"
                  TValue="string"
                  AllowCustomTags="true"
                  ValidateBy="TagBoxValidateBy.Tags"
                  @bind-Tags="@recipients.Data">
        </DxTagBox>
        <ValidationMessage For="@(() => recipients.Data)" />
    </p>
    <button type="submit">Submit</button>
</EditForm>

@code {
    EmailRecipients recipients = new EmailRecipients();

    private void HandleValidSubmit() {
        Console.WriteLine("OnValidSubmit");
    }
    private void HandleInvalidSubmit() {
        Console.WriteLine("OnInvalidSubmit");
    }
} 

EmailAddressesAttribute

public class EmailRecipients {
    [Required]
    [EmailAdresses(ErrorMessage = "Invalid email")]
    public IEnumerable<string> Data { get; set;}
} 

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
public class EmailAdressesAttribute: ValidationAttribute {
    public override bool IsValid(object value) {
        IEnumerable<string> data = value as IEnumerable<string>;
        if (data != null) {
            foreach (var item in data)
                if (!item.Contains("@") || !item.Substring(item.IndexOf('@')).Contains("."))
                    return false;
            return true;
        } else
            return false;
    }
}

For more information, refer to the following help topic: Validate Input.

Run Demo: TagBox - Validation