Validating forms
Check what people enter before a record is saved
When someone saves a create or edit form, StellarAdmin runs ASP.NET Core model validation before it saves the record. If a field isn't valid, StellarAdmin displays the form again with the values that were entered and the errors, and doesn't save the record.
The example below requires a reference of up to 12 characters, and between 1 and 20 travelers:
public class Booking
{
[Required, StringLength(12)]
public string Reference { get; set; } = "";
[Range(1, 20)]
public int Travelers { get; set; } = 1;
}StellarAdmin displays the errors of the fields on the form, and ignores the errors of properties that aren't on it. A [Required] property without a field doesn't stop the record from being saved.
StellarAdmin validates forms with the ASP.NET Core model validation pipeline, so validation libraries that plug into the pipeline work with StellarAdmin too. For example, to validate StellarAdmin's forms with FluentValidation validators, enable FluentValidation's automatic validation by calling AddFluentValidationAutoValidation() from the FluentValidation.AspNetCore package.
A custom data source can also return validation errors when it saves a record, such as when a reference is already in use.
When EF Core can't save the record
When EF Core reports a concurrency conflict, the form displays "This record changed while you were working. Reload it and try again." If the record was deleted in the meantime, StellarAdmin returns a 404 Not Found response.
When saving fails for any other reason, such as a duplicate value in a unique index, StellarAdmin logs the exception, and the form displays "This record couldn't be saved. Try again."