ANTOOZA-BACKEND/SharedKernel/Attributes/MaxFileSizeAttribute.cs

using Microsoft.AspNetCore.Http;
using System.Collections;
using System.ComponentModel.DataAnnotations;

namespace SharedKernel.Attributes;

/*
 * 파일 크기 제한
 */
[AttributeUsage(AttributeTargets.Property)]
public class MaxFileSizeAttribute : ValidationAttribute
{
    private readonly long _maxKBytes;

    public MaxFileSizeAttribute(long maxKBytes)
    {
        _maxKBytes = maxKBytes;
    }

    public override bool IsValid(object? value)
    {
        if (value is IEnumerable files)
        {
            foreach (var obj in files)
            {
                if (obj is IFormFile file && file.Length > _maxKBytes)
                {
                    return false;
                }
            }
        }

        return true;
    }

    public override string FormatErrorMessage(string name)
    {
        var template = string.IsNullOrWhiteSpace(ErrorMessage) ? "{0}의 크기는 최대 {1:N0}KB까지 허용됩니다." : ErrorMessage;

        return string.Format(template, name, _maxKBytes);
    }
}