89 lines
2.4 KiB
Markdown
89 lines
2.4 KiB
Markdown
|
---
|
||
|
|
tags:
|
||
|
|
- mongo-db
|
||
|
|
- node-js
|
||
|
|
- mongoose
|
||
|
|
- databases
|
||
|
|
---
|
||
|
|
|
||
|
|
# Update a MongoDB document
|
||
|
|
|
||
|
|
There are two methods for updating a document
|
||
|
|
|
||
|
|
- query first
|
||
|
|
- update first
|
||
|
|
|
||
|
|
## Query first document update
|
||
|
|
|
||
|
|
With this approach we first execute a
|
||
|
|
[query](Querying_a_Mongo_collection.md) to retrieve the document we
|
||
|
|
want to edit and then make the change. We use the `findById` method to identify
|
||
|
|
the document by its UUID and then `set` to update specified properties on the
|
||
|
|
document. The `set` method is one of many operators that can be used to update
|
||
|
|
values. For example there is also built-in operators for increment, renaming,
|
||
|
|
multiplying values.
|
||
|
|
|
||
|
|
Query first is best used when you want to secure the update with some prior
|
||
|
|
logic or to validate. For example you may not want to update a course if it is
|
||
|
|
listed as published. You could use a query to determine the publish status and
|
||
|
|
then only update the entry if it returns `isPublished: false`.
|
||
|
|
|
||
|
|
```js
|
||
|
|
async function updateCourseFromQuery(id) {
|
||
|
|
const course = await Course.findById(id);
|
||
|
|
if (!course) return;
|
||
|
|
course.set({
|
||
|
|
isPublished: true,
|
||
|
|
author: "A new author",
|
||
|
|
});
|
||
|
|
|
||
|
|
// Instead of an object, we could also set the updated properties individually
|
||
|
|
course.isPublished = true;
|
||
|
|
course.author = "Biggs Volunksire";
|
||
|
|
|
||
|
|
const result = course.save();
|
||
|
|
console.log(result);
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
## Update first document update
|
||
|
|
|
||
|
|
With this approach we don't bother with a prior query. We are confident that the
|
||
|
|
update is legitimate and do not need to first determine that certain conditions
|
||
|
|
are met.
|
||
|
|
|
||
|
|
To do this we directly use the `update` method, not `find`:
|
||
|
|
|
||
|
|
```js
|
||
|
|
async function updateCourseFromQuery(id) {
|
||
|
|
const result = await Course.update({ _id: id });
|
||
|
|
$set: {
|
||
|
|
// Invoke the set operator
|
||
|
|
author: "Terry Nutile";
|
||
|
|
isPublished: true;
|
||
|
|
}
|
||
|
|
console.log(result);
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
This function will just return some metadata about the update. It won't by
|
||
|
|
default return the updated value. To do this use the `findByIdAndUpdate()`
|
||
|
|
method instead of `update`:
|
||
|
|
|
||
|
|
```js
|
||
|
|
async function updateCourseFromQuery(id) {
|
||
|
|
const course = await Course.findByIdAndUpdate(id, {
|
||
|
|
$set: { // Invoke the set operator
|
||
|
|
author: 'Terry Nutile'
|
||
|
|
isPublished: true
|
||
|
|
}, {new: true}});
|
||
|
|
console.log(result)
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
If we don't add `{new: true}`, it will return the document before the update.
|
||
|
|
|
||
|
|
### Updating multiple documents at once
|
||
|
|
|
||
|
|
// Add: notes on this
|