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-rw-r--r--Validators/ISBNAttribute.cs26
1 files changed, 26 insertions, 0 deletions
diff --git a/Validators/ISBNAttribute.cs b/Validators/ISBNAttribute.cs
new file mode 100644
index 0000000..425e9e9
--- /dev/null
+++ b/Validators/ISBNAttribute.cs
@@ -0,0 +1,26 @@
+using System.ComponentModel.DataAnnotations;
+using LibraryAPI.Models;
+
+namespace LibraryAPI.Validators {
+ public class ISBNAttribute : ValidationAttribute {
+ public int ISBNlength { get; }
+
+ public ISBNAttribute(int isbn_length) {
+ ISBNlength = isbn_length;
+ }
+
+ public string GetErrorMessage() {
+ return $"ISBN strings must be {ISBNlength} characters long";
+ }
+
+ protected override ValidationResult? IsValid(object? value, ValidationContext validationContext) {
+ var book = (Book) validationContext.ObjectInstance;
+
+ if(book.ISBN.Length != ISBNlength) {
+ return new ValidationResult(GetErrorMessage());
+ }
+
+ return ValidationResult.Success;
+ }
+ }
+} \ No newline at end of file