如何從Angular中的foreach循環返回數組數據

Question

我正在遍歷嵌套對象以獲取一些數據。 這是可行的，但我似乎無法返回數據並在其他地方使用它。

我已經嘗試過將循環作為一個承諾，但也無濟於事。 我究竟做錯了什么？

data: any = {
    '1234': {
        url: 'https://example1.com/',
        path: 'uploads',
        link: 'https://example1.com/uploads',
    },
    '5678': {
        url: 'https://example2.com/',
        path: 'uploads',
        link: 'https://example2.com/uploads',
    }
}


onSubmit(formData) {

    this.formdata = formData;

    Object.keys(this.data).forEach(key => {
        if (key == this.formdata.pin) {
            const url = this.data[key].url;
            // have also tried this.url to no avail
        }
    });

    // says undefined
    console.log(url);

    // set up headers, etc...

    // I need to use here
    this.http.post(url, body, head)
    ...
}

Answer 1

onSubmit(formData) {

this.formdata = formData;
let url; // Define here so that its accessible
Object.keys(this.data).forEach(key => {
    if (key === this.formdata.pin) {
         url = this.data[key].url;
        // have also tried this.url to no avail
    }
});

// Now url is in scope
console.log(url);

    ...
}

Answer 2

將forEach切換到map可以簡化此過程； map返回值，而forEach則不。

舊：

Object.keys(this.data).forEach(key => {
    if (key == this.formdata.pin) {
        const url = this.data[key].url;
    }
});

// says undefined
console.log(url);

新增內容：（根據下面的評論，我還在此處添加了=== ）

const urls = Object.keys(this.data).map(key => {
    if (key === this.formdata.pin) {
        return this.data[key].url;
        // have also tried this.url to no avail
    }
});

console.log(urls);

地圖文檔和forEach文檔