Filter documents that do not have a property set - Prisma - prisma

Question

I have this example data:
const example = [
{
productId: 1,
name: "Husdady",
age: 21
},
{
name: "Vereth",
age: 19
},
{
name: "Mikaela",
age: 17
},
{
name: "Richard",
age: 20
},
{
productId: 4,
name: "Markus",
age: 24
},
{
productId: 8,
name: "Cecilia",
age: 18
},
{
productId: 1,
name: "Anton",
age: 16
}
]
console.log(example)
I have a 'User' model in prisma. So what I must achieve is to filter all those users that do not have a defined productId and also filter by productId.
For example, I want to filter all users that have product Id 1 and also all users that do not have a productId defined
I have tried with the following filter
this.prisma.users.findMany({
where: {
OR: [
{ productId: undefined },
{ productId: 1 }
]
}
})
This query gets me all the users that have '1' as the value of their 'productId' but it does not bring me the users that do not have a defined productId.
The expected result of the above query would be:
const result = [
{
productId: 1,
name: "Husdady",
age: 21
},
{
name: "Vereth",
age: 19
},
{
name: "Mikaela",
age: 17
},
{
name: "Richard",
age: 20
},
{
productId: 1,
name: "Anton",
age: 16
}
]
console.log(result)
I only get the users 'Husdady' and 'Anton'
const resultObtained = [
{
productId: 1,
name: "Husdady",
age: 21
},
{
productId: 1,
name: "Anton",
age: 16
}
]
console.log(resultObtained)
How I can resolve this problem?