无法将图片从Expo＆React Native和POST上传到Flask后端

Question

我正在尝试使用react native / expo上传图像，并将其发送到Python Flask后端服务器。但是，在我的Flask服务器中，出现以下错误： werkzeug.exceptions.BadRequestKeyError：400错误的请求：浏览器（或代理）发送了该服务器无法理解的请求。

以下是上传图片的代码（效果很好）：

import React from "react";
import {
  StyleSheet,
  Text,
  View,
  Image,
  Button,
  Alert,
  TouchableOpacity,
} from "react-native";
import * as ImagePicker from "expo-image-picker";
import * as Permissions from "expo-permissions";
import { editProfilePicture } from "../functions/network_authentication";
import { onPressHandler } from "../functions/utils";

export default class EditPicture extends React.Component {
  constructor(props) {
    super(props);
    this.handleChange = this.handleChange.bind(this);
    this.state = {
      image: null,
    };
  }
  handleChange(event) {
    this.setState({
      image: event,
    });
    console.log("handle change ok");
    console.log(this);
  }
  askForPermission = async () => {
    const permissionResult = await Permissions.askAsync(Permissions.CAMERA);
    if (permissionResult.status !== "granted") {
      Alert.alert("no permissions to access camera!", [{ text: "ok" }]);
      return false;
    }
    return true;
  };

  takeImage = async () => {
    // make sure that we have the permission
    const hasPermission = await this.askForPermission();
    if (!hasPermission) {
      console.log("no permission");
      return;
    } else {
      console.log("permission");
      // launch the camera with the following settings
      let image = await ImagePicker.launchCameraAsync({
        mediaTypes: ImagePicker.MediaTypeOptions.Images,
        allowsEditing: true,
        aspect: [3, 3],
        quality: 1,
        //base64: true,
      });
      console.log("image got");
      // make sure a image was taken:
      if (!image.cancelled) {
        console.log("image not canceled");
        console.log(image);
        this.handleChange(image);
      }
    }
  };
  render() {
    return (
      <View style={styles.container}>
        <TouchableOpacity
          style={{ justifyContent: "center", alignItems: "center" }}
          onPress={this.takeImage}
        >
          <Text
            style={{ alignSelf: "center", fontSize: 20, fontWeight: "bold" }}
          >
            Upload
          </Text>
        </TouchableOpacity>
        {this.state.image != null ? (
          <View
            style={{
              justifyContent: "center",
              alignItems: "center",
              alignSelf: "center",
              marginTop: "3em",
              height: "30%",
              width: "15%",
              borderWidth: 4,
              borderColor: "black",
            }}
          >
            <Image
              source={this.state.image}
              style={{width: "100%", height: "100%", alignSelf: "center"}}
            />
          </View>
        ) : null}
        <TouchableOpacity
          style={{
            width: "80%",
            height: "10%",
            alignSelf: "center",
            borderRadius: 8,
            borderWidth: 3,
            borderColor: "#000000",
            bottom: 20,
            position: "absolute",
            alignContent: "center",
            justifyContent: "center",
          }}
          onPress={() => {
            let result = editProfilePicture(this.state.image);
            result.then((res) => {
              if (res) {
                onPressHandler(
                  this.state.navigation,
                  "SuccessEdit",
                );
              }
            });
          }}
        >
          <Text style={{ alignSelf: "center", fontWeight: "bold" }}>
            Send the picture !
          </Text>
        </TouchableOpacity>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#fff",
    flexDirection: "column",
  },
});

如您所见，当我们按下发送图片时，我们正在运行editProfilePicture函数：

export const editProfilePicture = async (uploaded_image) => {
  let form_data = new FormData();
  form_data.append("input_image", uploaded_image, "photo.jpg");
  try {
    let response = await fetch(
      "127.0.0.1:5000/change_profile_picture",
      {
        body: form_data,
        method: "put",
        credentials: "include",
      }
    );
    if (response.ok) {
      let json = await response.json();
      return true;
    } else {
      console.log("Not OK");
      return false;
    }
  } catch (error) {
    console.error(error);
    return false;
  }
};

请求已发送到Flask服务器，但在我的端点中，我在此行遇到400错误：

@auth.route("/change_profile_picture", methods=["PUT"])
@jwt_refresh_token_required
def change_profile_picture():
    """
    To do when the other endpoints work
    """
    input_image = request.files["input_image"]  # HERE !

结论：我认为问题出在我发送图片的方式上。我该怎么办？我对Blob，Canvas等一无所知，因此欢迎一些代码行！