egametang/ET · error · Exception

to json error

Error message

to json error {obj.GetType().FullName}
{e}

What it means

Thrown by ET.MongoHelper.ToJson(object) when the MongoDB BSON driver's obj.ToJson(defaultSettings) raises during JSON serialization. It wraps any inner failure into a single Exception whose Message embeds the target type FullName and the original exception text. Note: the rethrow at line 36 does NOT pass the original exception as InnerException (no ', e'), so the stack trace is lost and only the formatted string survives.

Solutions

1. Inspect the embedded inner text in the message (the type FullName + inner message); fix the named type's serialization registration.
2. Ensure the type has a registered serializer: BsonSerializer.RegisterSerializer(...) or a BsonClassMap, and for polymorphism add [BsonDiscriminator]/[BsonKnownTypes].
3. If obj may be null, null-check before calling ToJson (the catch will itself NRE on obj.GetType()).
4. Consider passing the inner exception: throw new Exception(..., e) so the real stack trace is preserved.

Example fix

// before
string s = MongoHelper.ToJson(maybeNullObj);

// after
if (maybeNullObj == null) return null;
try { return MongoHelper.ToJson(maybeNullObj); }
catch (Exception e) { Log.Error($"serialize {maybeNullObj.GetType()} failed: {e}"); throw; }

// validate before serialize
if (obj == null) throw new ArgumentNullException(nameof(obj));
if (!BsonSerializer.IsTypeRegistered(obj.GetType()))
    throw new InvalidOperationException($"no bson serializer for {obj.GetType().FullName}");

try { return MongoHelper.ToJson(obj); }
catch (Exception e) { /* message already contains inner text; log obj type + e.Message */ Log.Error(e); throw; }

When it happens

Trigger: Calling MongoHelper.ToJson(obj) on an object whose runtime type has no registered BsonClassMap/serializer, a type with an unserializable member (e.g. an interface or Dictionary with non-serializable key), a circular reference, or passing obj == null (which also makes the catch itself NullReference via obj.GetType()).

Common situations: Sharing entities/messages over JSON (network, logs, config dumps), serializing dynamically-typed or polymorphic objects without [BsonKnownTypes], migrating classes and forgetting to register class maps, or null args after a refactor.

Related errors

• from json error
• from bson error
• from bson error
• from bson error
• from bson error

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/799ff58a6c800a2b. Report an issue: GitHub.

Appendix: source

Thrown at Packages/cn.etetet.core/Scripts/Core/Share/Serialize/MongoHelper.cs:36

            Indent = true, 
            IndentChars = "\t", 
            NewLineChars = "\n", 
            OutputMode = JsonOutputMode.Shell 
        };
        
        public static string ToJson(object obj)
        {
            try
            {
                if (obj is ISupportInitialize supportInitialize)
                {
                    supportInitialize.BeginInit();
                }
                return obj.ToJson(defaultSettings);
            }
            catch (Exception e)
            {
                throw new Exception($"to json error {obj.GetType().FullName}\n{e}");
            }
        }

        public static string ToJson(object obj, JsonWriterSettings settings)
        {
            try
            {
                if (obj is ISupportInitialize supportInitialize)
                {
                    supportInitialize.BeginInit();
                }
                return obj.ToJson(settings);
            }
            catch (Exception e)
            {
                throw new Exception($"to json error {obj.GetType().FullName}\n{e}");
            }
        }

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