反应动态输入表单显示错误一些问题

Question

我正在创建动态输入字段我正在验证一些必填字段我在数组中验证的输出我尝试在输入中显示错误值我导致了一些错误。我尝试了一些与索引数组的匹配，但我没有工作

代码沙盒：https://codesandbox.io/s/floral-bash-lrvkc?file=/src/App.js:0-2399

感谢帮助

import React, { useState } from "react";
import "./styles.css";

function App() {
  const [inputList, setInputList] = useState([{ firstName: "", lastName: "" }]);
  const [formError, setFormError] = useState([]);
  const [isSubmit, setisSubmit] = useState(false);

  // handle input change
  const handleInputChange = (e, index) => {
    const { name, value } = e.target;
    const list = [...inputList];
    list[index][name] = value;
    setInputList(list);
  };

  // handle click event of the Remove button
  const handleRemoveClick = (index) => {
    const list = [...inputList];
    list.splice(index, 1);
    setInputList(list);
  };

  // handle click event of the Add button
  const handleAddClick = () => {
    setInputList([...inputList, { firstName: "", lastName: "" }]);
  };
  const Submit = (e) => {
    e.preventDefault();
    const errorMsg = inputList.map((list, key) => {
      let error = {};
      if (!list.firstName) {
        error.errorfirstName = "FirstName is required";
      } else {
        error.errorfirstName = "";
      }
      if (!list.lastName) {
        error.errorlastName = "LastName is required";
      } else {
        error.errorlastName = "";
      }
      return error;
    });
    console.log(errorMsg);
    setFormError(errorMsg);
  };

  return (
    <div className="App">
      {inputList.map((x, i) => {
        return (
          <div className="box">
            <input
              name="firstName"
              placeholder="Enter First Name"
              value={x.firstName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <input
              className="ml10"
              name="lastName"
              placeholder="Enter Last Name"
              value={x.lastName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <div className="btn-box">
              {inputList.length !== 1 && (
                <button className="mr10" onClick={() => handleRemoveClick(i)}>
                  Remove
                </button>
              )}
              {inputList.length - 1 === i && (
                <button onClick={handleAddClick}>Add</button>
              )}
            </div>
          </div>
        );
      })}
      <button onClick={Submit}>Submit</button>
      <div style={{ marginTop: 20 }}>{JSON.stringify(inputList)}</div>
    </div>
  );
}

export default App;

Answer 1

请看下面的代码。我添加了一些代码 - 请参阅 // CHANGE HERE

标记的评论

import React, { useState } from "react";
import "./styles.css";

function App() {
  const [inputList, setInputList] = useState([{ firstName: "", lastName: "" }]);
  const [formError, setFormError] = useState([]);
  const [isSubmit, setisSubmit] = useState(false);

  // handle input change
  const handleInputChange = (e, index) => {
    const { name, value } = e.target;
    const list = [...inputList];
    list[index][name] = value;
    setInputList(list);
  };

  // handle click event of the Remove button
  const handleRemoveClick = (index) => {
    const list = [...inputList];
    list.splice(index, 1);
    setInputList(list);
  };

  // handle click event of the Add button
  const handleAddClick = () => {
    setInputList([...inputList, { firstName: "", lastName: "" }]);
  };

  // CHANGE HERE: a flag to be set when there is an error
  var isError = false;

  const Submit = (e) => {
    e.preventDefault();
    const errorMsg = inputList.map((list, key) => {
      let error = {};
      if (!list.firstName) {
        error.errorfirstName = "FirstName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorfirstName = "";
      }
      if (!list.lastName) {
        error.errorlastName = "LastName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorlastName = "";
      }
      return error;
    });
    console.log(errorMsg);
    setFormError(errorMsg);
    // CHANGE HERE: return false and prevent form submission in case of errors
    if (isError)
      return false;
  };

  // CHANGE HERE: added Error function
  const Error = () => {
    return <>
      {formError.map((error, i) => {
        var str = error.errorfirstName + " " + error.errorlastName;
        if (str !== ' ')
          return <p key={i.toString()}> {i} {str}</p>;
        return <></>
      })}
    </>;
  };

  return (
    <div className="App">
      {inputList.map((x, i) => {
        return (
          <div className="box">
            <input
              name="firstName"
              placeholder="Enter First Name"
              value={x.firstName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <input
              className="ml10"
              name="lastName"
              placeholder="Enter Last Name"
              value={x.lastName}
              onChange={(e) => handleInputChange(e, i)}
            />
            <div className="btn-box">
              {inputList.length !== 1 && (
                <button className="mr10" onClick={() => handleRemoveClick(i)}>
                  Remove
                </button>
              )}
              {inputList.length - 1 === i && (
                <button onClick={handleAddClick}>Add</button>
              )}
            </div>
          </div>
        );
      })}
      <button onClick={Submit}>Submit</button>
      // CHANGE HERE: show an error if any
      <Error />
      <div style={{ marginTop: 20 }}>{JSON.stringify(inputList)}</div>
    </div>
  );
}

export default App;

Answer 2

表格上面的答案我做了一些修改

import React, { useState } from "react";
import "./styles.css";

function App() {
  const [inputList, setInputList] = useState([{ firstName: "", lastName: "" }]);
  const [formError, setFormError] = useState([]);
  const [isSubmit, setisSubmit] = useState(false);

  // handle input change
  const handleInputChange = (e, index) => {
    const { name, value } = e.target;
    const list = [...inputList];
    list[index][name] = value;
    setInputList(list);
  };

  // handle click event of the Remove button
  const handleRemoveClick = (index) => {
    const list = [...inputList];
    list.splice(index, 1);
    setInputList(list);
  };

  // handle click event of the Add button
  const handleAddClick = () => {
    setInputList([...inputList, { firstName: "", lastName: "" }]);
  };

  // CHANGE HERE: a flag to be set when there is an error
  var isError = false;

  const Submit = (e) => {
    e.preventDefault();
    const errorMsg = inputList.map((list, key) => {
      let error = {};
      if (!list.firstName) {
        error.errorfirstName = "FirstName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorfirstName = "";
      }
      if (!list.lastName) {
        error.errorlastName = "LastName is required";
        // CHANGE HERE: set error flag
        isError = true;
      } else {
        error.errorlastName = "";
      }
      return error;
    });
    console.log(errorMsg);
    setFormError(errorMsg);
    // CHANGE HERE: return false and prevent form submission in case of errors
    if (isError) return false;
  };

  return (
    <div className="App">
      {inputList.map((x, i) => {
        return (
          <div className="box">
            <div>
              <input
                name="firstName"
                placeholder="Enter First Name"
                value={x.firstName}
                onChange={(e) => handleInputChange(e, i)}
              />
              {formError.map((error, index) => (
                <p key={index.toString()}>
                  {i == index ? (
                    <>
                      {index}
                      {error.errorfirstName}{" "}
                    </>
                  ) : null}
                </p>
              ))}
            </div>
            <div>
              <input
                className="ml10"
                name="lastName"
                placeholder="Enter Last Name"
                value={x.lastName}
                onChange={(e) => handleInputChange(e, i)}
              />
              {formError.map((error, index) => (
                <p key={index.toString()}>
                  {i == index ? (
                    <>
                      {index}
                      {error.errorlastName}{" "}
                    </>
                  ) : null}
                </p>
              ))}
            </div>
            <div className="btn-box">
              {inputList.length !== 1 && (
                <button className="mr10" onClick={() => handleRemoveClick(i)}>
                  Remove
                </button>
              )}
              {inputList.length - 1 === i && (
                <button onClick={handleAddClick}>Add</button>
              )}
            </div>
          </div>
        );
      })}
      <button onClick={Submit}>Submit</button>
    </div>
  );
}

export default App;

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