在 React Native 中向数组添加新对象

Question

我创建了一个表单来在主屏幕上上传图像和文本字段，但我面临一个问题，即它没有更新数组并且因此验证失败。我认为我的实现有问题

AddPost.js

const validationSchema = Yup.object({
  title: Yup.string().required().min(5).max(15).label("Title"),
  des: Yup.string().required().min(15).max(200).label("Description"),
  image: Yup.array().required().label("Image"),
});

class AddPost extends Component {
  render() {
    return (
      <Formik
        initialValues={{ title: "", des: "", image: [] }}
        onSubmit={(values, actions) => {
          actions.resetForm();
          this.props.addPost(values);
        }}
        validationSchema={validationSchema}
      >
        {(value) => (
          <View>
            <FormImage />
            <Text style={styles.error}>
              {value.touched.image && value.errors.image}
            </Text>
            <TextInput
              placeholder="Title"
              onChangeText={value.handleChange("title")}
              style={styles.input}
              value={value.values.title}
              onBlur={value.handleBlur("title")}
            />
            <Text style={styles.error}>
              {value.touched.title && value.errors.title}
            </Text>

这是我的表单域，我想一切都在这里

home.js

class Home extends Component {
  state = {
    modal: false,
    post: [
      {
        key: "1",
        title: "A Good Boi",
        des: "He's a good boi and every one know it.",
        image: require("../assets/dog.jpg"),
      },
      {
        key: "2",
        title: "John Cena",
        des: "As you can see, You can't see me!",
        image: require("../assets/cena.jpg"),
      },
    ],
    image: null,
  };


  addPost = (posts) => {
    posts.key = Math.random().toString();
    this.setState.post((currentPost) => {
      return [posts, ...currentPost];
    });
    this.state.modal();
  };

  render() {
    return (
      <Screen style={styles.screen}>
        <Modal visible={this.state.modal} animationType="slide">
          <TouchableWithoutFeedback onPress={Keyboard.dismiss}>
            <View style={styles.modalContainer}>
              <AddPost addPost={() => this.addPost} />
            </View>
          </TouchableWithoutFeedback>
        </Modal>
        <FlatList
          data={this.state.post}
          renderItem={({ item }) => (
            <>
              <Card
                title={item.title}
                subTitle={item.des}
                image={item.image}
                onPress={() => this.props.navigation.navigate("Edit", item)}
              />
            </>

我认为 addPost 方法有问题，因为我之前使用函数库做过，那次我只将文本添加到列表中并且它工作但在类库中我不知道这样做我只是尝试与我相同的方式在函数库中做了

FormImage.js

class FormImage extends Component {
  state = {
    image: null,
    hasCameraPermission: null,
  };

  async componentDidMount() {
    const { status } = await Permissions.askAsync(Permissions.CAMERA_ROLL);
    this.setState({ hasCameraPermission: status === "granted" });
  }

  _pickImage = async () => {
    let result = await ImagePicker.launchImageLibraryAsync({
      mediaTypes: ImagePicker.MediaTypeOptions.Images,
      allowsEditing: true,
      aspect: [4, 3],
    });

    if (!result.cancelled) {
      this.setState({ image: result.uri });
    }
  };

  render() {
    const { image } = this.state;
    return (
      <TouchableWithoutFeedback onPress={this._pickImage}>
        <View style={styles.container}>
          {!image && (
            <MaterialCommunityIcons
              color={colors.medium}
              name="camera"
              size={40}
            />
          )}
          {image && <Image style={styles.image} source={{ uri: image }} />}
        </View>
      </TouchableWithoutFeedback>
    );
  }
}

提交后

Answer 1

我假设你的 addPost 函数逻辑是错误的，

试试下面的代码

 addPost = (posts) => {
    posts.key = Math.random().toString();
    this.setState((prevState) => {
      return {...prevState, post: [...prevState.post, ...posts] };
    });
    this.state.modal();
  };

如果您遇到同样的错误，请告诉我。

Answer 2

您没有将图像更新为 formik，因此您会收到所需的错误是正常的。 首先在您的 AddPost 组件中将 formikProps 传递给 FormImage 组件。

return (
      <Formik
        initialValues={{ title: "", des: "", image: [] }}
        onSubmit={(values, actions) => {
          // actions.resetForm(); --> comment this
          this.props.addPost(values);
        }}
        validationSchema={validationSchema}
      >
        {(value) => (
          <View>
            <FormImage formikProps={value}/>
            <Text style={styles.error}>
              {value.touched.image && value.errors.image}
            </Text>
            <TextInput
              placeholder="Title"
              onChangeText={value.handleChange("title")}
              style={styles.input}
              value={value.values.title}
              onBlur={value.handleBlur("title")}
            />
            <Text style={styles.error}>
              {value.touched.title && value.errors.title}
            </Text>

在 FormImage 中使用该 formikProps 并调用 setFieldValue("image", result.uri) 来更新图像的 formik 值。

class FormImage extends Component {
  state = {
    image: null,
    hasCameraPermission: null,
  };

  async componentDidMount() {
    const { status } = await Permissions.askAsync(Permissions.CAMERA_ROLL);
    this.setState({ hasCameraPermission: status === "granted" });
  }

  _pickImage = async () => {
    let result = await ImagePicker.launchImageLibraryAsync({
      mediaTypes: ImagePicker.MediaTypeOptions.Images,
      allowsEditing: true,
      aspect: [4, 3],
    });

    if (!result.cancelled) {
      this.setState({ image: result.uri });
      this.props.formikProps.setFieldValue("image", result.uri);
    }
  };

  render() {
    const { image } = this.state;
    return (
      <TouchableWithoutFeedback onPress={this._pickImage}>
        <View style={styles.container}>
          {!image && (
            <MaterialCommunityIcons
              color={colors.medium}
              name="camera"
              size={40}
            />
          )}
          {image && <Image style={styles.image} source={{ uri: image }} />}
        </View>
      </TouchableWithoutFeedback>
    );
  }
}

在家里

addPost = (posts) => {
    console.log('add post');
    posts.key = Math.random().toString();
    this.setState((prevState) => {
      return {...prevState, post: [...prevState.post, ...posts], modal: 
      true };
    });
    // this.state.modal();
  };