egametang/ET · error · Exception

from json error: {str} {e}

Error message

from json error: {str}
{e}

What it means

Thrown by MongoHelper.FromJson<T>(string) when BsonSerializer.Deserialize<T>(str) fails. The helper re-wraps into a new Exception whose message includes the raw input string and the original exception text; here it DOES preserve the inner exception via ', e' (line 64), so the stack trace survives.

Source

Thrown at Packages/cn.etetet.core/Scripts/Core/Share/Serialize/MongoHelper.cs:64

                    supportInitialize.BeginInit();
                }
                return obj.ToJson(settings);
            }
            catch (Exception e)
            {
                throw new Exception($"to json error {obj.GetType().FullName}\n{e}");
            }
        }

        public static T FromJson<T>(string str)
        {
            try
            {
                return BsonSerializer.Deserialize<T>(str);
            }
            catch (Exception e)
            {
                throw new Exception($"from json error: {str}\n{e}");
            }
        }

        public static object FromJson(Type type, string str)
        {
            try
            {
                return BsonSerializer.Deserialize(str, type);
            }
            catch (Exception e)
            {
                throw new Exception($"from json error: {str}\n{e}");
            }
        }

        public static byte[] Serialize(object obj)
        {
            try

View on GitHub (pinned to 5cab01f7a8)

Solutions

1. Inspect the inner exception (preserved) and the printed input string to find the offending field/token.
2. Align T with the JSON: add missing members, register BsonClassMap, or add [BsonIgnoreExtraElements] for forward-compat.
3. Validate the string is non-empty and well-formed JSON before deserializing.
4. For migrated types use [BsonDefaultValue]/[BsonIgnoreExtraElements] to tolerate schema drift.

Example fix

// before
var e = MongoHelper.FromJson<MyEntity>(json);

// after
if (string.IsNullOrWhiteSpace(json)) throw new ArgumentException("empty json", nameof(json));
var e = MongoHelper.FromJson<MyEntity>(json);

if (string.IsNullOrWhiteSpace(str)) throw new ArgumentException("json is empty", nameof(str));

try { return MongoHelper.FromJson<T>(str); }
catch (Exception e) { Log.Error($"FromJson<{typeof(T).Name}> failed: {e}"); throw; }

When it happens

Trigger: Deserializing malformed JSON, JSON whose values do not map onto T (wrong field types, missing required fields), a JSON containing an unknown _t discriminator, or passing null/empty str.

Common situations: Loading saved entity state from JSON, reading config/network messages, schema migration where T changed but stored JSON did not, hand-edited JSON files, null strings after a failed read.

Related errors

• to json error {obj.GetType().FullName} {e}
• Serialize error {obj.GetType().FullName} {e}
• Serialize error {message.GetType().FullName} {e}
• from bson error: {type.FullName} {bytes.Length}
• from bson error: {type.FullName} {bytes.Length} {index} {cou

AI-assisted analysis of egametang/ET@5cab01f7a8 (2026-08-13). Data as JSON: /api/errors/2bad1961842735f8. Report an issue: GitHub.