MongoDB upsert array document with golang - mongodb

Question

I have a document like below：
{
"_id": "1.0",
files: [
{"name": "file_1", "size": 1024, "create_ts": 1570862776426},
{"name": "file_2", "size": 2048, "create_ts": 1570862778426}
]
}
And I want to upsert “files” with "file_x"：
1 if "file_x" already in "files", then update, for example "file_x" is：
{"name": "file_2", "size": 4096, "create_ts": 1570862779426}
after upsert document is：
{
"_id": "1.0",
files: [
{"name": "file_1", "size": 1024, "create_ts": 1570862776426},
{"name": "file_2", "size": 4096, "create_ts": 1570862779426}}
]
}
2 if "file_x" not in "files", insert it， for example "file_x" is：
{"name": "file_3", "size": 4096, "create_ts": 1570862779426}
after upsert document is :
{
"_id": "1.0",
files: [
{"name": "file_1", "size": 1024, "create_ts": 1570862776426},
{"name": "file_2", "size": 2048, "create_ts": 1570862778426},
{"name": "file_3", "size": 4096, "create_ts": 1570862779426}
]
}
So can I use one function to archive it ?

Answer 1

You will need to do this manually. There's no upsert mechanism for embedded structures inside a document.
First fetch the document, check if file_x is in the files list, if not, insert it. Then save the document back.
You should make sure that at any given time, only one program / goroutine is trying to do this, otherwise you will run into race conditions and file_x might get inserted multiple times.

Answer 2

There is not a single update operation in mongodb update language that will do what you want to do. You can get close by using $addToSet, which adds to a set of items if the item is not already there, but it will not update the item based on the match of a subset of fields. Your best option is to perform a read-update in memory-write.