I'm having a trouble with react hook form usefield array. Basically I'm trying to append and delete but the problem is when I'm deleting its deleting only the last element. append is working fine but suppose if I have 3 fields with values a,b,c and I want to remove b, when I'm pressing remove button of b then its removing c, if I try to remove a again its also removing c only from the UI.

Here is my codesandbox link for the code: Codesandbox

CodePudding user response：

I made some changes to your codesandbox and this should work:

import React from "react";
import { useForm, useFieldArray, Controller, useWatch } from "react-hook-form";
import ReactDOM from "react-dom";
// import Button from '@mui/material/Button';

import "./styles.css";

let renderCount = 0;

function App() {
  const { register, control, handleSubmit, reset, watch } = useForm({
    defaultValues: {
      parameters: [{ parameterName: "" }]
    }
  });

  const {
    fields: parameterfields,
    append: appendParameters,
    remove: removeParameters
  } = useFieldArray({
    control,
    name: "parameters"
  });

  const onSubmit = (data) => console.log("data", data);

  // if you want to control your fields with watch
  // const watchResult = watch("test");
  // console.log(watchResult);

  // The following is useWatch example
  // console.log(useWatch({ name: "test", control }));

  renderCount  ;

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <h1>Field Array </h1>
      <p>The following demo allow you to delete, append, prepend items</p>
      <span className="counter">Render Count: {renderCount}</span>
      <ul>
        {parameterfields.map((item, index) => {
          return (
            <div
              key={item.id}
              style={{ display: "flex", marginTop: 30 }}
            >
              <div style={{ width: "90%", marginRight: 20 }}>
                <Controller
                  name={`parameters.${index}.parameterName`}
                  control={control}
                  render={({ field: { onChange, value } }) => (
                    <div>
                      {console.log(item.parameterName)}
                      <input
                        name={`parameters[${index}].parameterName`}
                        variant="standard"
                        InputProps={{
                          disableUnderline: true
                        }}
                        // className={styles.title}
                        onChange={onChange}
                        defaultValue={item.parameterName}
                        placeholder="Parameter Name"
                      />
                    </div>
                  )}
                />
              </div>
              <div>
                <button
                  onClick={() => removeParameters(index)}
                  sx={{ width: 130, height: 50 }}
                  variant="outlined"
                >
                  Remove
                </button>
              </div>
            </div>
          );
        })}
      </ul>
      <section>
        <button
          type="button"
          onClick={() => {
            appendParameters({ 
              date: new Date(),
              parameterName: "" });
          }}
        >
          append
        </button>
      </section>

      <input type="submit" />
    </form>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);