{"componentChunkName":"component---src-templates-blog-post-js","path":"/Files-mern/","result":{"data":{"site":{"siteMetadata":{"title":"Ibrahim personal blog","author":"Ibrahim"}},"markdownRemark":{"id":"a9d59a03-4f7b-5f8f-b31e-bcd857322003","html":"

This article meant to be written for everything you need to know about file upload MERN stack specifically.

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if you want to escape this article for the code you can find here
\nSource Code

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Let’s get started

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1.Creating Server and Client instances

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I assume you have already installed npm, NodeJS & MongoDB, we need to create a react app.\nNOTE: remember to put your repos on an organized folder structure.\nOpen the terminal and use the following commands:

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npx create-react-app file-upload-mern\ncd ./file-upload-mern
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Also, we want to use axios to send the file to the server instance, to install axios:

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npm i axios
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here we created the react client-side app, we end with a file structure like this:

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file-upload-mern\n├── .gitignore\n├── public\n├── package.json    \n├── src\n│   └── App.js\n│   └── index.js\n│   └── App.css\n│   └── index.css\n│   └── serverWorker.js\n│   └── setupTests.js\n├── README.md
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Now, we need now to create the server-side app also, on the folder file-upload-mern write the following on the terminal:

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mkdir server\ncd ./server\nnpm init -y\ntouch server.js\ntouch model.js\nmkdir public
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To make sure we are on the same page this is the final file structure scheme:

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file-upload-mern\n├── .gitignore\n├── public\n├── package.json    \n├── src\n│   └── App.js\n│   └── index.js\n│   └── App.css\n│   └── index.css\n│   └── serverWorker.js\n│   └── setupTests.js\n├── server\n│   └── package.json\n│   └── public \n│   └── server.js\n│   └── node_modules\n│   └── model.js\n├── README.md
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To install the backend dependencies:

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npm i express\nnpm i mongoose\nnpm i multer
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To make things clear about the dependencies we installed:

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Now we created the server and the client sides so move to the next point.\n

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2.Write the code

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First, we will start with the client code by heading to /src/App.js\nto write the following:

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// destination  /src/App.js\n\nimport React from 'react';\nimport './App.css';\nimport axios from 'axios';\n\nclass App extends React.Component {\n\n  constructor(props) {\n      super(props);\n      this.state ={\n          file: null\n      };\n      this.onFormSubmit = this.onFormSubmit.bind(this);\n      this.onChange = this.onChange.bind(this);\n  }\n  onFormSubmit(e){\n      e.preventDefault();\n      const formData = new FormData();\n      formData.append('myfile',this.state.file);\n      const config = {\n          headers: {\n              'content-type': 'multipart/form-data'\n          }\n      };\n      axios.post(\"http://localhost:5000/upload\",formData,config)\n          .then((response) => {\n              alert(\"The file is successfully uploaded\");\n          }).catch((error) => {\n      });\n  }\n\n  onChange(e) {\n      this.setState({file:e.target.files});\n  }\n\n  render() {\n      return (\n          <form onSubmit={this.onFormSubmit}>\n              <h1>File Upload</h1>\n              <input type=\"file\" className=\"custom-file-input\" name=\"myImage\" onChange= {this.onChange} />\n              {console.log(this.state.file)}\n              <button className=\"upload-button\" type=\"submit\">Upload to DB</button>\n          </form>\n      )\n  }\n}\n\nexport default App;
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Here we created a form in which the user uploads the file and saves it in the app component state which after submitting will be transferred for the server-side.

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Now let head into the side we start with the /server/model.js

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var mongoose = require('mongoose');\n\n\nconst fileSchema = new mongoose.Schema({\n    meta_data:{}\n});\n\nmongoose.model(\"file\",fileSchema);
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And this is how we built the user schema sounds easy right?\n

\nNow let’s build the server instance which will listen on port 5000 on /server/server.js

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// destination /server/server.js\nconst express = require(\"express\");\nconst path = require(\"path\");\nconst multer = require(\"multer\");\nconst mongoose  = require(\"mongoose\");\nconst app = express();\nconst PORT = 5000;\nrequire(\"./model\")\nconst File = mongoose.model(\"file\");\nconst router = express.Router();\n\nconst storage = multer.diskStorage({\n   destination: \"./public/\",\n   filename: function(req, file, cb){\n      cb(null,\"IMAGE-\" + Date.now() + path.extname(file.originalname));\n   }\n});\n\nconst upload = multer({\n   storage: storage,\n   limits:{fileSize: 1000000},\n}).single(\"myfile\");\n\nconst obj =(req,res) => {\n   upload(req, res, () => {\n      console.log(\"Request ---\", req.body);\n      console.log(\"Request file ---\", req.file);//Here you get file.\n      const file = new File();\n      file.meta_data = req.file;\n      file.save().then(()=>{\n      res.send({message:\"uploaded successfully\"})\n      })\n      /*Now do where ever you want to do*/\n   });\n}\n\nrouter.post(\"/upload\", obj);\n\napp.use(router);\n\napp.get(\"/\",(req,res)=>{\n   return res.send(\"<p>hello!</p>\");\n});\n\nmongoose.connect(\"mongodb://localhost/file-upload\",{\n   useUnifiedTopology: true,\n   useNewUrlParser: true,\n   useCreateIndex: true,\n}).then(()=>{console.log(\"DB is connected\")})\n\napp.listen(PORT,()=>{\n   console.log(\"\\u{1F525}\\u{1F680} app listen on port\",PORT,\"\\u{1F525}\\u{1F680}\")\n});
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Note: path library is a built in NodeJS library to deal with file systems paths operations and dealing with it is more recommended than using RegEx.

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3.Running the code

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First, make sure you are on the root directory of the project via terminal and open two instances of terminals one for the client and second for the server-side of the project:\nTo run the server

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node ./server/server.js
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To run the client

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npm start
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4.Dealing with exporting files to the client side

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you need to make the files Directory public just by exporting it as a static asset using Express

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const path = require(\"path\");\napp.use(express.static(path.join(__dirname, \"./public/\")));
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Conclusion

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We discussed simple details in terms of MERN stack development note that you may get a CORS permission error and that happens because the client fetches data from different origin API and fixing it from your browser by allowing all origins of APIs and it has an extension on chrome to handle it properly.\nHappy coding.

","timeToRead":5,"frontmatter":{"title":"Dealing with files via MERN stack","date":"March 05, 2020","spoiler":null,"tags":"ExpressJS MongoDB NodeJS React"},"fields":{"slug":"/Files-mern/","langKey":"en"}}},"pageContext":{"slug":"/Files-mern/","previous":{"fields":{"slug":"/Functional/","langKey":"en","directoryName":"Functional","maybeAbsoluteLinks":[]},"frontmatter":{"title":"Functional programming"}},"next":{"fields":{"slug":"/custom-async-dispatch/","langKey":"en","directoryName":"custom-async-dispatch","maybeAbsoluteLinks":[]},"frontmatter":{"title":"Write your own custom asyncDispatch middleware"}},"translations":[],"translatedLinks":[]}}}