text: import { Schema } from 'mongoose';
  
  export default {
    studentId: {
      type: Schema.Types.ObjectId,
      ref: 'Student',
      required: true,
    },
    subjectId: {
      type: Schema.Types.ObjectId,
      ref: 'Subject',
      required: true,
    },
    state: {
      type: String,
      required: false,
    },
  };
  