Why does GraphQl return null? - mongodb

Question

I am trying to create an API with MongoDB, Express Js, Node and GraphQl. I have a collection called characters, with the following schema:
const CharacterSchema = Schema({
page:{
type: Number,
required: true
},
data:{
type: Array,
required: true
}
});
I have 25 objects in my database with the above schema. I have a query to query the characters, passing the page number by parameter:
type Character {
_id: ID
name: String!
status: String!
species: String!
type: String!
gender: String!
origin: String!
image: String!
episode: [String]
location: String!
created: String!
}
type Page {
page: Int!
data: [Character]!
}
type Query {
characters(page: Int!): Page!
}
And this is its resolver:
export const resolvers = {
Query: {
characters: async (_, args) => {
let data = await Character.findOne({ page: args.page });
return data;
},
},
};
This is the query Im using to fetch the data:
query($page: Int!) {
characters(page: $page) {
page
data {
name
status
species
type
gender
origin
image
episode
location
created
}
}
}
Executing the query by passing the page number, it returns perfectly the information I ask for.
Now I want to get only one character by its ID. I created a query and a type to fetch only one character by its id:
type CharacterById {
result: Character
}
type Query {
characters(page: Int!): Page!,
character(id: ID): CharacterById
}
This is its resolver:
export const resolvers = {
Query: {
//this works perfectly
characters: async (_, args) => {
let data = await Character.findOne({ page: args.page });
return data;
},
//returns obj but show me null
character: async (_, args) => {
//first method returns the object perfectly
let data = await Character.aggregate([
{ $unwind: "$data" },
{ $match: { "data._id": args.id } },
]);
return data[0].data // returns object
//second method returns the object perfectly
let data = await Character.findOne({"data._id": args.id})
let character = data.data.find(item => item._id === args.id)
return character // returns object
},
},
};
I explain the above: The query “character” is the resolver that I created to get from the database the character with the id passed by parameter.
I try it with two methods. Both of them return me perfectly the object with the id passed by parameter, but when I try to use the query:
query($characterId: ID!) {
character(id: $characterId) {
result {
name
status
species
type
gender
origin
image
episode
location
created
}
}
}
It returns me a null, when it should return me the object:
{
"data": {
"character": null
}
}
why doesn't it bring me the object?
please help me I am very stressed and frustrated that this is not working for me :(