我必须使用axios将文件和一些json数据发送到服务器，并将其解码为express server，以便将json存储在mongodb中，并使用multer进行文件处理。

Question

我想要创建一个端点，它应该将文件存储在服务器端，以及应该从同一点接收的一些json数据将存储在mongodb上。我使用axios从React发送请求。这是我的密码。

  const [companyFile, setCompanyFile] = useState(null);
  const [company, setCompany] = useState({
    name: "",
    websiteUrl: "",
    email: "",
    companyLocation: "",
  });

  const AddCompany = async (e) => {
    if (companyFile) {
      e.preventDefault();
      let formData = new FormData();
      formData.append("company-file", companyFile);
      formData.append("company", JSON.stringify(company));

      axios({
        method: "post",
        url: `http://localhost:8080/company/add`,
        data: formData,
        withCredentials: true,
        header: {
          Accept: "application/json",
          "Content-Type": "multipart/form-data",
        },
      }).then((res) => console.log(res.data));
    } else {
      console.log("file not selected!!!!");
    }
  };

现在我不知道如何检查它是否到达后端快车服务器？或者，如果来了，那么如何从请求中检索application/json数据以供进一步处理。

我的问题是，如果数据被发送到后端express，那么如何处理后端中的数据(即获取json数据以在mongodb中创建文档)。这是我的company/add代码

let upload = multer({
  storage: multer.diskStorage({
    destination: async (req, file, cb) => {
      if (!company) {
        throw Error("Company cannot be found!");
      }
      let companyName = req.company.name;
      let path = `./uploads/${companyName}/files`;
      if (!fs.existsSync(path)) {
        fs.mkdirSync(path, { recursive: true });
      }
      cb(null, path);
    },
    filename: async (req, file, cb) => {
      //  ** with student auth Code

      req.filename = req.company.name;
      cb(null, filename + path.extname(file.originalname));
    },
  }),
}).single("company-file");

// Add Company
module.exports.add_company = async (req, res) => {
  try {
    // Here I want to extract that company object to create new company
    console.log(req.file);
    try {
      const newcompany = await Company.create(company);
      req.company = newcompany;
      upload(req, res, async () => {
        try {
          const companyFile = await CompanyFile.create({
            companyId: req.company._id,
            path: `./uploads/${req.company.name}/file/${req.filename}.pdf`,
          });
          req.companyFile = companyFile;
        } catch (err) {
          res.status(400).json({ success: false, message: err.message });
          // ** code for resume-upload using student authentication middleware
          if (
            fs.existsSync(
              `./uploads/${req.company.name}/file/${req.filename}.pdf`
            )
          ) {
            fs.unlink(`./uploads/${req.company.name}/file/${req.filename}.pdf`);
          }
        }
      });
      res.status(201).json({
        success: true,
        message: "Company Drive Added Successfully.",
        company: req.company,
        companyFile: req.companyFile,
      });
    } catch (err) {
      res.status(400).json({
        success: false,
        errors: err,
        message: "Error while applying company drive.",
      });
    }
  } catch (err) {
    console.log(err);
  }
};

Answer 1

来自文档

Multer向请求对象添加一个body对象和一个或多个文件对象。body对象包含表单文本字段的值，文件或文件对象包含通过表单上载的文件。

因此，在您的示例中，您可以通过以下操作访问和解析company字段：

const company = JSON.parse(req.body.company);

此外，您还需要确保将multer中间件应用于您的控制器。

app.post('/company/add', upload.single('company-file'), function (req, res, next) {
  // req.file is the `company-file` file
  // req.body.company will hold the company text field
})