How to post form data from reactjs to controller in mvc asp.net

Question

I am new to React. I am trying to create a form in asp.net with react. when posting form data from reactjs to controller in mvc asp.net, the data is not getting passed. I have shared my code below. Please let me know what changes I have to make to make it work.

controller:

[Route("InputEmployee")]

        public void InputEmployee([FromBody]EmployeeTable Employee)
        {
            db.EmployeeTables.Add(Employee);
                   db.SaveChanges();           
        }

Reactjs code:

class InputValues extends React.Component {
    constructor(props) {
        super(props);
        this.handleSubmit = this.handleSubmit.bind(this);
    }

    handleSubmit(e) {
        e.preventDefault();
        const data = new FormData();
        data.append = this.firstName.value;
        data.append = this.lastName.value;
        data.append = this.gender.value;
        data.append = this.designation.value;
        data.append = this.salary.value;
        data.append = this.city.value;
        data.append = this.country.value;
        var xhr = new XMLHttpRequest();
        xhr.open('post', this.props.url, true);
        xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        xhr.onreadystatechange = function() {
            if(xhr.readyState == XMLHttpRequest.DONE && xhr.status == 200) {
                // Do something on success
            }
        }
        xhr.send(data);
    }

    render() {
        return(
          <div>       
              <form onSubmit={this.handleSubmit}>
          <label htmlFor="FirstName">First Name </label><br/>
          <input id="FirstName" type="text"  placeholder="Enter First Name" ref={(firstName) => this.firstName = firstName} />
          <br/><br/>
          <label htmlFor="LastName">Last Name: </label><br/>
          <input id="LastName" type="text"  placeholder="Enter Last Name"  ref={(lastName) => this.lastName = lastName} />
          <br/><br/>
          <label htmlFor="Gender">Gender: </label><br/>
          <input id="Gender" type="text"  placeholder="Gender"  ref={(gender) => this.gender = gender} />
          <br/><br/>
          <label htmlFor="Designation">Designation: </label><br/>
          <input id="Designation" type="text"  placeholder="Enter Designation" ref={(designation) => this.designation = designation} />
          <br/><br/>
          <label htmlFor="Salary">Salary: </label><br/>
          <input id="Salary" type="number"  placeholder="Enter Salary" ref={(salary) => this.salary = salary} />
          <br/><br/>
          <label htmlFor="City">City: </label><br/>
          <input id="City" type="text"  placeholder="Enter City" ref={(city) => this.city = city} />
          <br/><br/>
          <label htmlFor="Country">Country: </label><br/>
          <input id="Country" type="text"  placeholder="Enter Country" ref={(country) => this.country = country} />
          <p>
            <button type="submit">Submit</button>
          </p>
        </form>
      </div>
    );
          }
};

ReactDOM.render(<InputValues url="api/Employee/InputEmployee" />,
          document.getElementById('grid1'))   

values not getting passed:

after making changes in append:

Answer 1

You're not building your FormData object correctly, append is a function so you need to use it as such:

data.append = ...; // wrong, overwrites the append function
data.append('key', 'value'); // correct, calls the function

Also, I'd recommend using the native Fetch API for sending web requests as it's a lot neater than working with raw XHR requests. It's not 100% cross-browser yet but there are various libraries you can use as a polyfill e.g. whatwg-fetch