使用提取填充JSONArray

Question

我正在尝试填充一个数组，该数组将以JSON格式在POST请求中发送。问题在于，当它发送到后端时，它会收到JSONArray null。

我的构造函数是这样的：

    constructor(props) {
        super(props);

        this.state = {
            name: '',
            text: '',
            date: '',
            treatment: [],
            treatments: [],
            app: '',
            appointments: [],
            dropdownOpen: false,
            dropdownOpen2: false
        }
        this.handleSubmit = this.handleSubmit.bind(this);
    }

    handleSubmit(event) {
        event.preventDefault();
        fetch('http://localhost:8080/annotations', {
            method: 'POST',
            headers: {'Content-Type':"application/json; charset=utf-8"},
            body: JSON.stringify({
                name: this.state.name,
                text: this.state.text,
                date: this.state.date,
                treatment: [{
                    name: this.state.treatment.name,
                    type: this.state.treatment.type,
                    price: this.state.treatment.type,
                    create_date: this.state.treatment.create_date,
                    ann: this.state.treatment.ann
                }],
                app: this.state.app
            })
        }).then(response => response.json())
          .then(function(myJson) {
              console.log(JSON.stringify(myJson));
          })
          console.log(this.state.treatment)
              //.then(data => this.setState({ name: data.name, text: data.text, date: data.text, treatment: data.treatment, app: data.app }))
        }

console.log(this.state.treatment)显示正确填充了数组处理，但是console.log(JSON.stringify(myJson))将treatments显示为null。如何填充格式正确的JSONArray？

谢谢！