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我有一个非常奇怪的问题。我有一个后端 api 可以将 json 数据导入我的 mongodb。

在屏幕上，我有一个上传按钮来上传文件，为此我使用了 react-dropzone。例如认为我有一个像“db.json”这样的文件，在这个文件中有一个如下的 json

{
"datapointtypes":[
    {"id":"Wall plug","features":[{"providesRequires":"provides","id":"Binary switch"},{"providesRequires":"requires","id":"Binary sensor","min":"1","max":"2"}],"parameters":[{"id":"Communication type","type":"Communication type"}],"functions":[{"id":"Electricity"},{"id":"Switch"}]},
    {"id":"Door sensor","features":[{"providesRequires":"provides","id":"Binary sensor"}],"parameters":[{"id":"Communication type","type":"Communication type"}],"functions":[{"id":"Door"},{"id":"Sensor"}]}
],
"datatypes":[
    {"id":"Communication type","type":"enum","values":[{"id":"Zwave"},{"id":"Zigbee"}]},
    {"id":"Zigbee network address","type":"decimal","min":1,"max":65336,"res":1},
    {"id":"Serial port","type":"string"}
],
"features":[
    {"id":"Zwave receiver","exposedtype":"Zwave command","functions":[{"id":"Communication"}]},
    {"id":"Zigbee receiver","exposedtype":"Zigbee command","functions":[{"id":"Communication"}]},
    {"id":"Binary switch","exposedtype":"On off state","functions":[{"id":"Actuator"}]},
    {"id":"Binary sensor","exposedtype":"On off state","functions":[{"id":"Sensor"}]}
],
"servicetypes":[
    {"id":"Room controller","datapointtype":"Room controller","DelayActive":false,"DelayValue":""},
    {"id":"Xiaomi door sensor","datapointtype":"Door sensor","parameters":[{"id":"Zigbee network address","type":"Zigbee network address"},{"id":"Zigbee node id","type":"Zigbee node id"}],"parametervalues":[{"id":"Communication type","value":"Zigbee"}]}
],
"systems":[
    {"id":"system 2","services":[{"serviceType":"Room controller","id":"servis 1"}],"serviceRelations":[{"serviceName":"servis 1","featureName":"Binary sensor"}],"parametervalues":[{"id":"Delay","paramName":"Delay","serviceType":"Room controller","value":"binary"}]},
    {"id":"system 3","services":[{"serviceType":"Room controller","id":"servis 1"}],"serviceRelations":[{"serviceName":"servis 1","featureName":"Binary sensor"}],"katid":"7"}
]
}

问题是这样的。如果浏览器控制台打开，那么我的代码运行成功，我可以将 json 数据导入我的 mongodb。但如果浏览器控制台关闭，我会收到“SyntaxError：JSON 输入意外结束”错误。

这是我在导入按钮上使用的功能

class FileUpload extends Component {
state = {
    warning: ""
}

uploadFile = (files, rejectedFiles) => {
    files.forEach(file => {
        const reader = new FileReader();

        reader.readAsBinaryString(file);
        let fileContent = reader.result;

        axios.post('http://localhost:3001/backendUrl', JSON.parse(fileContent),
            {
                headers: { 
                    "Content-Type": "application/json" 
                }
            })
            .then(response => {
                this.setState({warning: "Succeed"})
            })
            .catch(err => {
                console.log(err)
            });
    });
}

render() {
    return (
        <div>
            <Dropzone className="ignore" onDrop={this.uploadFile}>{this.props.children}
            </Dropzone>
            {this.state.warning ? <label style={{color: 'red'}}>{this.state.warning}</label> : null}
        </div>
    )
}

}

我做错了什么或者是什么原因造成的？你能帮助我吗？

谢谢

4

1 回答 1

0

FileReader异步读取文件，因此您必须使用回调来访问
我将使用的结果，readAsText而不是readAsBinaryString在 JSON 中没有非 ascii 字符的情况下
最后，JSON.parse将 JSON 字符串转换为对象（或任何类型）。fileContent已经是 JSON，所以保持原样。

    const reader = new FileReader();
    reader.onlooad = (e) => {
        let fileContent = this.result;

        axios.post('http://localhost:3001/backendUrl', fileContent,
        {
            headers: { 
                "Content-Type": "application/json" 
            }
        })
        .then(response => {
            this.setState({warning: "Succeed"})
        })
        .catch(err => {
            console.log(err)
        });
    }
    reader.readAsText(file);
于 2018-08-07T13:47:31.880 回答