73 lines
2.4 KiB
Markdown
73 lines
2.4 KiB
Markdown
---
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categories:
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- Databases
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tags: [mongo-db, node-js, mongoose]
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---
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# Update a MongoDB document
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There are two methods for updating a document
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- query first
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- update first
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## Query first document update
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With this approach we first execute a [query](/Databases/MongoDB/Querying_a_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.
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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`.
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```js
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async function updateCourseFromQuery(id) {
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const course = await Course.findById(id);
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if (!course) return;
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course.set({
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isPublished: true,
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author: "A new author",
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});
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// Instead of an object, we could also set the updated properties individually
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course.isPublished = true;
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course.author = "Biggs Volunksire";
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const result = course.save();
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console.log(result);
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}
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```
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## Update first document update
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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.
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To do this we directly use the `update` method, not `find`:
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```js
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async function updateCourseFromQuery(id) {
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const result = await Course.update({ _id: id });
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$set: {
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// Invoke the set operator
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author: "Terry Nutile";
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isPublished: true;
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}
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console.log(result);
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}
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```
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This function will just return some metadata about the update. It won't by default return the updated value. To do this use the `findByIdAndUpdate()` method instead of `update`:
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```js
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async function updateCourseFromQuery(id) {
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const course = await Course.findByIdAndUpdate(id, {
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$set: { // Invoke the set operator
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author: 'Terry Nutile'
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isPublished: true
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}, {new: true}});
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console.log(result)
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}
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```
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If we don't add `{new: true}`, it will return the document before the update.
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### Updating multiple documents at once
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// Add: notes on this
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