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StopShopping.Services/Models/Validator/ImageFileValidationAttribute.cs

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+using FileSignatures;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace System.ComponentModel.DataAnnotations;
+
+public class ImageFileValidationAttribute : ValidationAttribute
+{
+    public ImageFileValidationAttribute(long length)
+    {
+        Length = length;
+    }
+
+    public long Length { get; set; }
+
+    protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
+    {
+        var fileInspector = validationContext.GetRequiredService<IFileFormatInspector>();
+        if (null == fileInspector)
+        {
+            return new ValidationResult("未配置文件验证器");
+        }
+        if (value is IFormFile file)
+        {
+            var result = Validate(fileInspector, file);
+            if (null != result)
+                return result;
+        }
+        else if (value is IFormFileCollection files)
+        {
+            foreach (var f in files)
+            {
+                var result = Validate(fileInspector, f);
+                if (null != result)
+                    return result;
+            }
+        }
+
+        return ValidationResult.Success;
+    }
+
+    private ValidationResult? Validate(IFileFormatInspector fileInspector, IFormFile file)
+    {
+        if (file.Length > Length)
+            return new ValidationResult("文件太大");
+        var format = fileInspector.DetermineFileFormat(file.OpenReadStream());
+        if (null == format)
+            return new ValidationResult("文件格式不支持");
+        return null;
+    }
+}