I am working on mern stack application where user will enter model name, its field names with types and it will automatically generate CRUD APIs for user.
for eg: user enters model name (register) field (name:string, pass:string), system will generate crud APIs with post delete applied on these fields.

我在Mern堆栈应用程序中工作，用户将输入模型名称，其类型和字段名称，它将自动生成用户的CRUD API。例如：用户输入模型名称(注册)字段(名称：字符串，传递：字符串)，系统将生成对这些字段应用POST DELETE的CRUD API。

But when I hit the API using the frontend or ThunderClient, it shows me this error. I even tried to place the GET, PUT, and DELETE requests inside the post Controller, but I still encounter the same error. I have debugged it using the console and consulted ChatGPT, but still no progress.

但当我使用前端或ThunderClient点击API时，它显示了这个错误。我甚至尝试将GET、PUT和DELETE请求放在POST控制器中，但仍然遇到相同的错误。我已经使用控制台进行了调试，并咨询了ChatGPT，但仍然没有进展。

Data and API Route

数据和API路由

http://localhost:4000/api/v1/model/create-model
{
  "name": "Product",
  "fields": [
    { "name": "name", "type": "String" },
    { "name": "price", "type": "Number" },
    { "name": "description", "type": "String" }
  ]
}

ERROR

误差率

MongoDB connected
Received request: {
  name: 'Product',
  fields: [
    { name: 'name', type: 'String' },
    { name: 'price', type: 'Number' },
    { name: 'description', type: 'String' }
  ]
}
Error: UserDefinedModel validation failed: fields.0: Cast to [string] failed for value "[\n' +
  "  { name: 'name', type: 'String' },\n" +
  "  { name: 'price', type: 'Number' },\n" +
  "  { name: 'description', type: 'String' }\n" +
  ']" (type string) at path "fields.0" because of "CastError"
    at ValidationError.inspect (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\error\validation.js:50:26)
    at formatValue (node:internal/util/inspect:805:19)
    at inspect (node:internal/util/inspect:364:10)
    at formatWithOptionsInternal (node:internal/util/inspect:2279:40)
    at formatWithOptions (node:internal/util/inspect:2141:10)
    at console.value (node:internal/console/constructor:352:14)
    at console.warn (node:internal/console/constructor:385:61)
    at createModel (file:///C:/Users/user/Desktop/API%20MERN%20Stack/backend/controllers/ModelController.js:27:13)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
  errors: {
    'fields.0': CastError: Cast to [string] failed for value "[\n' +
      "  { name: 'name', type: 'String' },\n" +
      "  { name: 'price', type: 'Number' },\n" +
      "  { name: 'description', type: 'String' }\n" +
      ']" (type string) at path "fields.0" because of "CastError"
        at SchemaArray.cast (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\schema\array.js:389:15)
        at SchemaType.applySetters (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\schematype.js:1201:12)
        at model.$set (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\document.js:1423:22)
        at model.$set (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\document.js:1148:16)
        at model.Document (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\document.js:166:12)
        at model.Model (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\model.js:123:12)
        at new model (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\mongoose\lib\model.js:5108:15)
        at createModel (file:///C:/Users/user/Desktop/API%20MERN%20Stack/backend/controllers/ModelController.js:14:19)
        at Layer.handle [as handle_request] (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\express\lib\router\layer.js:95:5)
        at next (C:\Users\user\Desktop\API MERN Stack\backend\node_modules\express\lib\router\route.js:144:13) {
      stringValue: `"[\\n' +\n` +
        `  "  { name: 'name', type: 'String' },\\n" +\n` +
        `  "  { name: 'price', type: 'Number' },\\n" +\n` +
        `  "  { name: 'description', type: 'String' }\\n" +\n` +
        `  ']"`,
      messageFormat: undefined,
      kind: '[string]',
      value: '[\n' +
        "  { name: 'name', type: 'String' },\n" +
        "  { name: 'price', type: 'Number' },\n" +
        "  { name: 'description', type: 'String' }\n" +
        ']',
      path: 'fields.0',
      reason: [CastError],
      valueType: 'string'
    }
  },
  _message: 'UserDefinedModel validation failed'
}

Model Schema

模型架构

// models/Model.js
import mongoose from 'mongoose';

const userDefinedModelSchema = new mongoose.Schema({
  name: String,
  fields: [
    {
      name: String,
      type: String,
    },
  ],
});

export default mongoose.model('UserDefinedModel', userDefinedModelSchema);

Model Controller

模型控制器

// controllers/ModelController.js
import mongoose from 'mongoose';
import UserDefinedModel from '../models/Model.js';

export const createModel = async (req, res) => {
  try {
    const { name, fields } = req.body;
    console.log('Received request:', req.body);

    if (!name || !fields || !Array.isArray(fields)) {
      return res.status(400).json({ error: 'Invalid input data' });
    }

    const model = new UserDefinedModel({ name, fields });
    await model.save()

    const schema = {};
    fields.forEach((field) => {
      schema[field.name] = field.type;
    });

    const generatedModel = mongoose.model(name, new mongoose.Schema(schema));

    console.log('Model created successfully');
    return res.status(201).json({ message: 'Model created successfully' });
  } catch (error) {
    console.error(error);
    return res.status(500).json({ error: 'Internal server error' });
  }
};

Model Route

模型路线

// routes/ModelRoutes.js
import express from 'express';
import { createModel } from '../controllers/ModelController.js';

const router = express.Router();

// Create a new model based on user input
router.post('/create-model', createModel);

export default router;

index.js

Index.js

import express from 'express';
import dotenv from 'dotenv';
import mongoose from 'mongoose';
import cors from 'cors';
import cookieParser from 'cookie-parser';
import userRoute from './routes/users.js';
import authRoute from './routes/auth.js';
import modelRoute from './routes/model.js';
import { createModel } from './controllers/ModelController.js';

dotenv.config();
const app = express();
const port = process.env.PORT || 4000;
const corsOptions = {
  origin: true,
  credentials: true,
};

mongoose.set('strictQuery', false);
const connect = async () => {
  try {
    await mongoose.connect(process.env.MONGO_URI, {
      useNewUrlParser: true,
      useUnifiedTopology: true,
    });

    console.log('MongoDB connected');
  } catch (error) {
    console.error('MongoDB connection failed');
  }
};

app.use(express.json());
app.use(cors(corsOptions));
app.use(cookieParser());

app.use("/api/v1/auth", authRoute);
app.use("/api/v1/users", userRoute);
app.use("/api/v1/model", modelRoute);

// Place this route definition after initializing your routes
app.post('/api/v1/model/create-model', createModel);

app.listen(port, () => {
  connect();
  console.log('Server listening on port', port);
});

When I hit the API using the frontend or ThunderClient, it shows me this error. I even tried to place the GET, PUT, and DELETE requests inside the post Controller, but I still encounter the same error. I have debugged it using the console and consulted ChatGPT, but still no progress.

当我使用前端或ThunderClient点击API时，它会显示以下错误。我甚至尝试将GET、PUT和DELETE请求放在POST控制器中，但仍然遇到相同的错误。我已经使用控制台进行了调试，并咨询了ChatGPT，但仍然没有进展。