I am creating my Express-GraphQL api where I can store everything in MongoDB. I am at the point where I have something like this:

Project Mongo model:

const { Schema, model } = require("mongoose");

const projectSchema = new Schema({
  name: {
    type: String,
    require: true,
  },
  offer: [{ type: String }],
});

module.exports = model("Project", projectSchema);

I deleted all fields except these 2. The field offer must be an array of files - for example you can have there 2-3 pdfs.

In my types I created Project type:

const Project = new GraphQLObjectType({
  name: "Project",
  fields: () => ({
    _id: { type: GraphQLNonNull(GraphQLString) },
    name: { type: GraphQLNonNull(GraphQLString) },
    offer: { type: GraphQLList(GraphQLString) }, 
  }),
});

I am wondering is there a way of creating a mutation that you can add/upload files in this offer field?

editProject: {
      type: Project,
      args: {
        projectId: { type: GraphQLNonNull(GraphQLString) },
        offer: { type: GraphQLList(GraphQLString) },  
      },

      async resolve(parentValue, args) {
        //some code here
      },
    },

If I have some mutation like that and how should I pass the files? If anybody have been doing something like this before I would be very thankful to share experience as I am:

1. not sure if it is possible
2. don't know how to pass the file in GraphQL mutation query
3. don't know how exactly to store file in mongoDB (probably with GridFS)

Thanks a lot!