【发布时间】：2021-03-24 09:33:13
【问题描述】：
我对使用 reduce 方法进行数组转换感到困惑。我不知道如何用文字键处理嵌套对象。
为了带来一些优势，我会发布一些我写的例子，它工作正常：
// consider flat array of objects
const names = [
{ name: "Jaden", sname: "Smith", age: 33 },
{ name: "Will", sname: "Smith", age: 12 },
{ name: "Jada", sname: "Smith", age: 29 },
{ name: "Jose", sname: "Varho", age: 21 },
{ name: "Josephina", sname: "Varho", age: 44 },
{ name: "Keanu ", sname: "Reeves", age: 44 }] ;
// suppose i need to transform that array to this shape:
/* {
"Smith": {
"Jaden": 33,
"Will": 12,
"Jada": 29
},
"Varho": {
"Jose": 21,
"Josephina": 44
},
"Reeves": {
"Keanu ": 44
}
}
*/
// this reducer do it's fine:
const shapeIt = (acc, item) => {
console.log('acc:', JSON.stringify(acc));
acc[item.sname] = { ...acc[item.sname], [item.name]: item.age }
return acc
}
const transformShape= (arr) => {
return arr.reduce((acc, item) => shapeIt(acc, item), {});
}
transformShape(names); //gives required shape
所以现在，让我们想象一下我有更复杂的数组，例如：
const flatArray = [
{ "blockId": "first-block", "sectionId": "first-section", "fieldId": "_1", "value": "0" },
{ "blockId": "first-block", "sectionId": "first-section", "fieldId": "_2", "value": "1" },
{ "blockId": "first-block", "sectionId": "second-section", "fieldId": "_1", "value": "1" },
{ "blockId": "second-block", "sectionId": "first-section", "fieldId": "_1", "value": "1" },
{ "blockId": "second-block", "sectionId": "some-section", "fieldId": "_2", "value": "3" },
{ "blockId": "third-block", "sectionId": "other-section", "fieldId": "_1", "value": "3" }];
// and i strictly need to get this shape of object:
/* {
"first-block": {
"first-section": {
"_1": "0",
"_2": "1"
},
"second-section": {
"_1": "1"
}
},
"second-block": {
"first-section": {
"_1": "1"
},
"some-section": {
"_2": "3"
}
},
"third-block": {
"other-section": {
"_1": "3"
}
}
}
*/
此时我正在编写这种 reduce 函数。它有效，但它只给了我块中每个部分的最后一个 fieldId 键。如果一个块中的部分有多个fieldId - 它会丢失它。我在看累加器，发现只有具有不同 blockId、sectionId 的键被累加，但fieldId 的键没有不同。
const shapeComplex = (acc, item) => {
console.log('acc:', JSON.stringify(acc));
acc[item.blockId] = { ...acc[item.blockId], [item.sectionId]: { [item.fieldId]: item.value } }
return acc
}
const transformComplex = (arr) => {
console.log('initialArr: ', arr)
return arr.reduce((acc, item) => shapeComplex(acc, item), {});
}
transformComplex(flatArray);
// it gives me shape with only last idField in same section and block:
/*
{
"first-block": {
"first-section": {
"_1": "0"
},
"second-section": {
"_1": "1"
}
},
"second-block": {
"first-section": {
"_1": "1"
},
"some-section": {
"_2": "3"
}
},
"third-block": {
"other-section": {
"_1": "3"
}
}
}
*/
请帮忙。
【问题讨论】：
标签： javascript arrays dictionary object reduce