Mongoose/Node: push element into document field of type array?

user_12188968 0
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I have a Mongoose schema with a field of type array, intended for containing several strings:

const exampleSchema = new.mongooseSchema({
      field1: String,
      field2: String,
      field3: [String]
})

I am setting up the backend to concatenate/push new strings into the field3 array, hoping to get something like this:

{
   field1: 'some string',
   field2: 'some other string',
   field3: [
              'string inside array1',
              'string inside array2',
              'string inside array3',
           ]
}

I am trying to do this with findByIdAndUpdate() an was trying things like spread operators to concatenate new strings into field 3, but I am not fully sure of how to use the syntax.

Is there any clean way of doing this without having to create an new updated object to replace the entire document?

mongoose node.js schema arrays javascript
2 Answers

You only need $push.

Check this example to know the syntaxis.

Using mongo is like this

db.collection.update({
  /* Your find object*/
},
{
  "$push": {
    "field3": "another string"
  }
})

Using $push you can add a value into an array. Easy.

And using moongoose is exactly the same, you have to pass the push object into parameters.

model.findByIdAndUpdate(your_id, {
  "$push": {
    "field3": "another string"
  }
})
user_134642790

How I have learned to update a small part of an item in mongoose is the following:

const example = await exampleSchema.findById(id)

// Return if non existing
if (!example )
  return res
    .status(404)
    .send(`Example with id:${id} was not found.`)

// Sets the new field3
example.field3 = [...example.field3, req.body.addedField3]

try {
  const result = await example.save()
  res.send(result)
} catch (exeption) {
  res.status(400).send(exeption.message)
}

This is wrapped in a router.put from express.Router

user_71853140
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