How to Retrieve MongoDB Documents by _ID Array with Golang?

Retrieving MongoDB Documents by _ID Array with Golang

Problem:

You possess an array containing MongoDB object _IDs. To efficiently retrieve all the corresponding documents, you seek a query that utilizes the mgo and bson packages.

Solution:

To construct the query, begin by examining the stored _IDs. If they are strings, your initial query using bson.M{"_id": bson.M{"$in": ids}} is accurate.

However, if the _IDs are object identifiers in hexadecimal form, a conversion is necessary. Follow these steps:

1. Initialize an array oids to hold the converted object IDs.
2. Iterate through the original ids array, converting each ID to bson.ObjectId using bson.ObjectIdHex.
3. Update your query to use oids instead of the original ids.

Here's the updated code for querying with object IDs:

<code class="go">oids := make([]bson.ObjectId, len(ids))
for i := range ids {
  oids[i] = bson.ObjectIdHex(ids[i])
}
query := bson.M{"_id": bson.M{"$in": oids}}</code>

By following these steps, you can effectively retrieve all MongoDB documents corresponding to the specified _ID array.

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