Initial commit

1 files changed, 64 insertions, 0 deletions

diff --git a/ExceptionMiddleware.cs b/ExceptionMiddleware.cs
new file mode 100644
index 0000000..ba4049a
--- /dev/null
+++ b/ExceptionMiddleware.cs
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+using HyperBooru.ApiModels;
+using System.Reflection;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Text.Json.Serialization.Metadata;
+
+namespace HyperBooru;
+
+// Middleware class to intercept API controller exceptions and
+// return said exceptions to API clients as serialized JSON objects
+public sealed class ExceptionMiddleware {
+    private RequestDelegate next;
+
+    public ExceptionMiddleware(RequestDelegate next) =>
+        this.next = next;
+
+    public async Task Invoke(HttpContext context) {
+        try {
+            await next(context);
+        } catch(HBException e) {
+            context.Response.ContentType = "application/json";
+            context.Response.StatusCode  =
+                e.GetType().GetCustomAttribute<ExceptionStatusCodeAttribute>()?.StatusCode ??
+                StatusCodes.Status500InternalServerError;
+
+            context.Response.Clear();
+
+            await context.Response.WriteAsJsonAsync(e);
+        } catch(Exception) {
+            context.Response.StatusCode = StatusCodes.Status500InternalServerError;
+            context.Response.ContentType = "application/json";
+
+            context.Response.Clear();
+
+            await context.Response.WriteAsJsonAsync(new ServerException());
+        }
+    }
+}
+
+// This class is needed as the JSON serializer often fails to serialize
+// members of the native 'Exception' class
+public sealed class ExceptionJsonResolver : DefaultJsonTypeInfoResolver {
+    public override JsonTypeInfo GetTypeInfo(Type type, JsonSerializerOptions options) {
+        var info = base.GetTypeInfo(type, options);
+
+        if(!typeof(Exception).IsAssignableFrom(type))
+            return info;
+
+        string[] excludedProps = [
+            "data",
+            "hResult",
+            "helpLink",
+            "innerException",
+            "source",
+            "stackTrace",
+            "targetSite"
+        ];
+
+        foreach(var p in info.Properties.Where(p => excludedProps.Contains(p.Name)))
+            p.ShouldSerialize = (_, _) => false;
+
+        return info;
+    }
+}