如何使用 promise 动态填充下拉选项

Question

import { getCustomer } from './Customers';
let optionItems=[];

export const LOV: React.FunctionComponent = () => {
  const loadCustomer = async () => {
  const data = await getCustomer();
  for (var i=0; i < data.value.length ; ++i)
  {
   optionItems.push({
    key: data.value[i].CustomerId,
    text: data.value[i].CustomerName
  });
 }
}
useEffect(() => {
 loadCustomer();
}, [])

return (
  <SearchableDropdown options={optionItems}/>    
);};

Code in Customers.tsx

export const getCustomer = async (): Promise<any> => {
const response = await 
$.ajax({
    url: apiURL,
    type: "GET",
    headers: headers,
    data: null,
    cache: false,
    beforeSend: function (request) {
      request.setRequestHeader("Authorization", 'Bearer ' + accessToken); 
    }
})
.done( function (data) {
    return data;
})
.fail(function (jqXHR) {
    if (jqXHR.status == 401) {
        promptAuth(jqXHR.getResponseHeader("WWW-Authenticate"));
    } 
    else {
        console.log("NOT 401");
    }
});  
return response;
}

I'm trying to populate a dropdown dynamically using a promise. I'm using Fluent-react Dropdown. getCustomer() loads values to const data. However, I can't see any values in the dropdown even though data is not null. Please help.

Fluent Dropdown => https://developer.microsoft.com/en-us/fluentui#/controls/web/dropdown

Answer 1

Your optionsItems need to be reactive. Try using useState -hook

export const LOV: React.FunctionComponent = () => {
  const [optionItems, setOptionItems] = useState([]);
  const loadCustomer = async () => {
  const data = await getCustomer();
  const options = [];
  for (var i=0; i < data.value.length ; ++i)
  {
   options.push({
    key: data.value[i].CustomerId,
    text: data.value[i].CustomerName
  });
 }
 setOptionItems(options)
}
useEffect(() => {
 loadCustomer();
}, [])

return (
  <SearchableDropdown options={optionItems}/>    
);};

Answer 2

Please make sure your data.value[i].CustomerId and data.value[i].CustomerName are valid strings. You need to supply string, but it looks like your API call returns null there. After you fix this problem, together with Stutje's solution your app should start to work.