chore: add image validation

Models/Carousel.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.Http;
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
+using pwt_0x01_ng.Models.Validation;
 
 namespace pwt_0x01_ng.Models
 {
@@ -10,6 +11,7 @@ namespace pwt_0x01_ng.Models
 		[Required]
 		public string DataTarget { get; set; }
 		[NotMapped]
+		[FileTypeAttr("image")]
 		public IFormFile Image { get; set; }
 		[Required]
 		[StringLength(255)]

Models/Validation/FileTypeAttr.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using Microsoft.AspNetCore.Http;
+
+namespace pwt_0x01_ng.Models.Validation
+{
+	public class FileTypeAttr : ValidationAttribute, IClientModelValidator
+	{
+		private readonly string type;
+		public FileTypeAttr(string type){
+			this.type = type.ToLower();
+		}
+
+		protected override ValidationResult IsValid(object value, ValidationContext validationContext) {
+			if (value == null) {
+				/* img is optional as of now */
+				return ValidationResult.Success;
+			} else if (value is IFormFile iff) {
+				if(iff.ContentType.ToLower().Contains(type)) {
+					return ValidationResult.Success;
+				} else {
+					return new ValidationResult(GetErrorMessage(validationContext.MemberName), new List<string> { validationContext.MemberName });
+				}
+			}
+			throw new NotImplementedException($"Attribute {nameof(FileTypeAttr)} not implemented for object {value.GetType()}.");
+		}
+
+		protected string GetErrorMessage(string member_name) => $"make sure your {member_name} really is an image ({type}).";
+
+		public void AddValidation(ClientModelValidationContext ctx){
+			MergeAttribute(ctx.Attributes, "data-val", "true");
+			MergeAttribute(ctx.Attributes, "data-val-content", GetErrorMessage("File"));
+			MergeAttribute(ctx.Attributes, "data-val-filetype", type);
+		}
+
+		private bool MergeAttribute(IDictionary<string, string> attributes, string key, string value){
+			if (attributes.ContainsKey(key)){
+				return false;
+			}
+
+			Attributes.Add(key, value);
+			return true;
+		}
+	}
+}

pwt-0x01-ng.csproj

@@ -28,6 +28,7 @@
 			<Folder Include="Migrations\pgsql" />
 			<Folder Include="Models\Database" />
 			<Folder Include="Models\Database\Conf" />
+			<Folder Include="Models\Validation" />
 			<Folder Include="wwwroot\images\carousels" />
 			<Folder Include="wwwroot\images\products" />
 		</ItemGroup>