MongoDB读取字段内容有空如何处理

MongoDB中的读取的字段有几个NULL值，结果转换时候总数报错，求大佬解答

[DataX插件运行时出错, 具体原因请参看DataX运行结束时的错误诊断信息 .]. - java.lang.NumberFormatException: Character N is neither a decimal digit number, decimal point, nor "e" notation exponential mark.

{
"setting":{
"speed":{
"channel":1
}
},
"content":[
{
"reader":{
"name":"mongodbreader",
"parameter":{
"address":[
"192.168.1.2:6010"
],
"dbName":"ams",
"collectionName":"test_tb",
"username":"test_reader",
"userPassword":"****************",
"column":[
{
"name":"schoolId",
"type":"string"
}
]
}
},
"writer":{
"name":"mysqlwriter",
"parameter":{
"column":[
"school_id"
],
"connection":[
{
"jdbcUrl":"jdbc:mysql://192.168.1.1:3020/ods",
"table":[
"ods.test1"
]
}
],
"password":"****************",
"username":"test",
"writeMode":"insert"
}
}
}
]
}

Start with the mongodbreader configuration and the reported NumberFormatException, then identify which field and value trigger conversion. The issue names no source file or test and does not define the expected handling for NULL values, so a reproducible case and agreed behavior are needed before implementation.

Written by the indexing model from the issue text.