Managing schema changes with MongoDB

Working with Data Drivers
1

How to handle if document structure after production changes.

Suppose I had 500 documents like this:
{
name : ‘n1’
height : ‘h1’
}

Later if I decide to add all the documents in below format:
{
name : ‘n501’
height : ‘h501’
weight : ‘w501’
}

I am using cursor.All(&userDetails) to decode(deserialize) in GoLang to get the output of the query in struct userDetails. If I modify the structure of further documents and userDetails accordingly, it will fail for the first 500 documents?

How to handle this change?

2

Hi Sahil,

The driver will only decode the fields that exist in the document and the struct, so you should be able to add a Weight field to your struct and everything should work. For the first 500 documents, the driver will leave the Weight field empty. You can use a regular string and check for Weight != "" or a *string and check for Weight != nil to determine if the field was empty depending on your use case.

1 Like