如何通过使用 lodash 连接嵌套数组对象来生成新数组

Question

I have an array of objects, and each objects may contain another array of objects, I want to concatenate values of nested array and generate a new array.

For example

lessons = [
 {
   id: 1,
   description: string,
   material: [{obj1}, {obj2}]
 },
 {
   id: 2,
   description: string,
   material: [{obj3}]
 },
 {
   id: 3,
   description: string,
   material: [{obj4}, {obj5}, {obj6}]
 }
]

I want to generate a new array only contains material, expected output would like this

materials = [
   {obj1},
   {obj2},
   {obj3},
   {obj4},
   {obj5},
   {obj6}
 ]

how can I do that by using lodash?

Answer 1

You can use .flatMap to iterate over lessons , and return all the material lists in one array:

 const lessons = [ { id: 1, description: 'string', material: [{obj1:1}, {obj2:2}] }, { id: 2, description: 'string', material: [{obj3:3}] }, { id: 3, description: 'string', material: [{obj4:4}, {obj5:5}, {obj6:6}] } ]; const res = _.flatMap(lessons, ({ material = [] }) => material); console.log(res);

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