所以我尝试通过将用户在用户模型中的角色从用户改为教练来让用户成为教练。

const mongoose = require('mongoose')
const Schema = mongoose.Schema

const UserSchema = new Schema({
    firstname : {
        type : String,
        required : true
    },
    lastname : {
        type : String,
        required : true
    },
    email : {
        type : String,
        required : true,
        unique : true
    },
    verified : {
        type : Boolean,
        default : false
    },
    password : {
        type : String,
        required : true,
        minLength : 3
    },
    role : {
        type : String,
        enum : ['admin', 'coach', 'user'],
        default : 'user'
    }
})

module.exports = mongoose.model('User', UserSchema)

下面是教练模型：

const mongoose = require('mongoose')
const Schema = mongoose.Schema

const CoachSchema = new Schema({
    coach : {
        type : mongoose.Schema.Types.ObjectId,
        ref : 'User'
    },
    team : {
        type : mongoose.Schema.Types.ObjectId,
        ref : 'Team'
    }
    
})

module.exports = mongoose.model('Coach', CoachSchema)

在创建新教练时，该特定用户的ID被传递到参数中，然后用户模型中的角色数据被切换到教练。教练的控制器如下所示：

const Coach = require('../models/Coach')
const User = require('../models/User')
const Team = require('../models/Teams')

exports.createCoach = async (req, res)=>{
    try {
        const userId = req.params.id
        const coach_data = await User.findById(userId)
        const {password, verified, ...other} = coach_data._doc
        console.log(other);
        const team = req.body.team
        const team_data = await Team.findById(team)

        const user = await User.findById(userId)
        if(!user) return res.status(400).json({
            error : 'User not found'
        })
        
        const coach = new Coach({
            coach : other,
            team : team_data
        })

        if(user.role === 'coach') return res.status(404).json({
            error : 'User is already a coach'
        })

        

        const updateUser = await User.findOneAndUpdate({ _id : userId}, {
            role : 'coach'
        },
        {
            new : true
        }
        )

        await coach.save()
        res.status(200).json('User has been made coach')

    } catch (error) {
        console.log(error);
        res.status(500).json(error)
    }
}

exports.getAllCoaches = async(req, res)=>{
    try {
        const coaches = await Coach.find()

        res.status(200).json(coaches)
    } catch (error) {
        res.status(500).json(error)
    }
}

这是教练的路由器：

const router = require('express').Router()
const coachController = require('../controllers/coachController')

router.post('/create-coach/:id', coachController.createCoach)
router.get('/get-coaches', coachController.getAllCoaches)

module.exports = router

这是我的数据库现在的样子[[1]：https://i.stack.imgur.com/3WclF.png[1]