The error message “readstartdocument can only be called when currentbsontype is document, not when currentbsontype is string” suggests that there is an issue with the BSON format being processed.
BSON is a binary representation of JSON-like documents. It is used primarily in MongoDB for data storage and network communication. When parsing BSON data, it is important to follow the correct sequence and ensure that the current BSON type is valid for the operation being performed.
The error in question specifically indicates that the code is attempting to call the readStartDocument() function when the current BSON type is a string. The readStartDocument() function is used to start reading a BSON document and expects the current BSON type to be a “document”. Therefore, this error occurs when the input does not adhere to the expected BSON structure.
Here’s an example to illustrate this situation:
String bsonData = "invalid bson data";
BsonReader bsonReader = new BsonReader(bsonData);
// Reading a start document, which causes the error
bsonReader.readStartDocument(); // Error: readstartdocument can only be called when currentbsontype is document, not when currentbsontype is string
In the example above, we are trying to read a BSON document using an invalid BSON data representation. It results in an error because the readStartDocument() function expects the current BSON type to be a document, but it is a string (as indicated by the “invalid bson data” comment).
To resolve this issue, you need to ensure that the BSON data used for parsing is in the correct format and that the parsing sequence is followed accurately.