Mongodb.Bson BsonBinaryWriter can't write field with name-CodePudding

I'm trying to write int value to BsonBinaryWriter using WriteInt32, but receive exception "WriteName can only be called when State is Name, not when State is Initial".

code sample

using MongoDB.Bson;
using MongoDB.Bson.IO;
        
BsonBinaryWriter writer = new BsonBinaryWriter(new MemoryStream());
writer.WriteInt32("t", 1); // receive exception here

CodePudding user response：

you should call WriteStartDocument first since what you're doing is creating a BSON document. So you're trying to add t : 1 value, but given that BSON document should roughly speaking correspond to JSON rules, you should open a bracket { (via WriteStartDocument) and close it at the end of a document (via WriteEndDocument).

See:

        using var memoryStream = new MemoryStream();
        using var writer = new BsonBinaryWriter(memoryStream);
        writer.WriteStartDocument();
        writer.WriteInt32("t", 1); // receive exception here
        writer.WriteEndDocument();

        memoryStream.Position = 0;

        using var reader = new BsonBinaryReader(memoryStream);
        var context = BsonDeserializationContext.CreateRoot(reader);
        var document = BsonDocumentSerializer.Instance.Deserialize(context);
        Console.WriteLine(document.ToString()); // => { "t" : 1 }