如何使用 typescript 从 React 中的状态创建新的 object？

Question

I have a state in react containing an array of files. How can I create a new object of type DocumentRequestModel instead? This is what I got so far. documents is my state containing my files.

export class DocumentRequestModel implements IDocumentRequestModel {
Data!: string;
FileName!: string;
...

This is what I got so far but I get the error message: Type '(string | undefined)[][] | undefined' is not assignable to type 'DocumentRequestModel'. Type 'undefined' is not assignable to type 'DocumentRequestModel'.

const documentModel: DocumentRequestModel = documents?.map(document => [
  document.preview,
  document.name
]);

This is how documents look.

  0: File
    name: "BOM_BR4666_PROJECTTYPE F_04_06_2020.xlsx"
    lastModified: 1586170093516
    lastModifiedDate: Mon Apr 06 2020 12:48:13 GMT+0200 (Central European Summer Time) {}
    webkitRelativePath: ""
    size: 3948
    type: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
    preview: "blob:http://localhost:4000/6d4be14b-0c09-45f9-b2c3-50

Answer 1

You can do it by:

const [docModel,setDocModel] = React.useState<DocumentRequestModel>()

or you want to defined it in array

const docModel = new Array<DocumentRequestModel>()

and in you mapping, the documents might be undefined. You might wanna check if it is not undefined before you call the map function

const documentModel: Array<DocumentRequestModel> = documents && documents.map(document => [
  document.preview,
  document.name
]);