How to Find a Document by ID Using mgo Library in Golang?
Oct 31, 2024 pm 08:51 PMFind ID with mgo Library in Golang
In the provided code, a common issue arises when trying to find a document by its ID using the mgo library in Golang. The key to understanding this error lies in the nature of object IDs in MongoDB.
Understanding Object IDs
Object IDs in MongoDB are unique 12-byte hexadecimal values that serve as the primary key for every document. However, when working with Golang, these IDs are often represented as 24-character hexadecimal strings. This is because these strings encode the 12 bytes of the object ID using two hexadecimal digits per byte.
The Error
The error message "ObjectIDs must be exactly 12 bytes long (got 24)" indicates that the code is attempting to use a 24-character string as an object ID. However, MongoDB expects a 12-byte object ID, which is not what the 24-character string represents.
The Solution
The solution to this issue is to use the bson.ObjectIdHex() function to convert the 24-character hexadecimal string into a valid bson.ObjectId. The modified code should look like this:
<code class="go">err = coll.FindId(bson.ObjectIdHex(message.ID)).One(&result)</code>
Now, the err variable will correctly indicate whether the document with the specified ID was found.
Converting Back
In scenarios where you have a bson.ObjectId and need to obtain its 24-character hexadecimal representation, you can use the ObjectId.Hex() method.
Additional Information
It is important to note that while the error message suggests that the length discrepancy was 24 bytes, it is actually 12 bytes. This is because the size of an object ID is 12 bytes, but the error message also includes the quotes that surround the hexadecimal string.
The above is the detailed content of How to Find a Document by ID Using mgo Library in Golang?. For more information, please follow other related articles on the PHP Chinese website!

Hot Article

Hot tools Tags

Hot Article

Hot Article Tags

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Go language pack import: What is the difference between underscore and without underscore?

How to implement short-term information transfer between pages in the Beego framework?

How to convert MySQL query result List into a custom structure slice in Go language?

How do I write mock objects and stubs for testing in Go?

How can I define custom type constraints for generics in Go?

How can I use tracing tools to understand the execution flow of my Go applications?

How to write files in Go language conveniently?
