MongoDB Node.JS insertOne error: "Type 'string' is not assignable to type 'ObjectId | undefined"

Question

I try to insert one document into the collection, but I get this error when I specify the _id field of the inserted document. So how can I insert a document with _id of a type other than ObjectId?

The following code gives me that error. When I remove the _id, everything goes fine but the _id will be generated automatically. I just want it to be a string type. I know this is possible. I can make _id string using MongoDB shell.

async function foo() {
  const users = client.db("test").collection("users")
  users.insertOne({
    _id: "a string",
    name: "Tom",
    age: 26,
  })
}

Why do you have to overwrite the default _id field if it's already auto incrementing ? If you need a string, can't you just add another field ? — akuiper
– akuiper, Commented Oct 12, 2021 at 2:41
If you want to use a custom string for _id you need to specify that in the schema mongoosejs.com/docs/guide.html#_id otherwise it expects specifically a ObjectId or a string version of an object id (specific length). Did you do that in your schema? — Alexander Staroselsky
– Alexander Staroselsky, Commented Oct 12, 2021 at 2:55
@AlexanderStaroselsky I've gone through this link you paste. It seems that this is not the official driver provided by MongoDB. I'm wondering if I can achieve this using official mongodb package? — Yan
– Yan, Commented Oct 12, 2021 at 3:39

Andrius Urbaitis · Accepted Answer · 2022-03-22 13:55:00Z

7

If you type your collection with _id: string it should work

type usertype = {
  _id: string,
  name: string,
  age: number
}

async function foo() {
  await client.connect()
  const users = client.db("test").collection<usertype>("users")
  const result = await users.insertOne({
    _id: "custom string",
    name: "Tom",
    age: 26,
  })
  console.log(result)
}

that should give you the result you're looking for

answered Mar 22, 2022 at 13:55

Andrius Urbaitis

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Comments

Yan · Accepted Answer · 2021-10-12 04:05:20Z

0

thanks for your answers and comments. I finally figure out the solution.

async function foo() {
  await client.connect()
  const users = client.db("test").collection("users")
  const result = await users.insertOne({
    _id: "custom string",
    name: "Tom",
    age: 26,
  } as any)
  console.log(result)
}

I'm new with TypeScript and MongoDB. I don't know if this is a bug when the mongodb package comes from common JS to TypeScript.

answered Oct 12, 2021 at 4:05

Yan

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