CODEWITHSUNDEEP
reactjsapiasync-awaitdialogflow-esuse-effect
Rainer Winkler
Rainer Winkler

Reputation: 565

How can I make sure that function 1 ends before function 2 starts within useeffect hook?

I created a chatbot and want to initiate two Dialogflow API calls within a useEffect Hook. Function 1 and function 2 are both async api calls. The wanted result is that it first finishes function 1 and then starts with function 2, but currently function 2 returns the value faster than function 1.

Do you have any idea how I can tell function 2 to wait until function 1 returns a value?

useEffect(
    () => {
      createChatSessionId();
      fetchEventAnswerFromDialogflow("Startevent" + chatId, chatId); // function 1
      fetchEventAnswerFromDialogflow("Frageevent1", chatId); // function 2
    }, // eslint-disable-next-line
    []
  );

Upvotes: 0

Views: 57

Answers (1)

Robin Chauhan
Robin Chauhan

Reputation: 61

API Calls are asynchronous. When the compiler hits an async statement, it doesnt wait for it to finish, instead calls next statement.

Option one, (Using .then block) :-

  useEffect(
    () => {
      createChatSessionId();
      fetchEventAnswerFromDialogflow("Startevent" + chatId, chatId).then(rep=>{
      fetchEventAnswerFromDialogflow("Frageevent1", chatId);})
        .catch(err){
          console.log(err)
         }
    }, // eslint-disable-next-line
    []
  );

Option two - As per ES6 using async await. I'd suggest not to make useEffect callback as async, instead make a new async function inside useEffect and call that.

useEffect(
    () => {
      createChatSessionId();
      const getData = async() =>{
         await fetchEventAnswerFromDialogflow("Startevent" + chatId, chatId);
         await fetchEventAnswerFromDialogflow("Frageevent1", chatId);  //Can remove await 
             //here, depending upon usecase
      }
      getData();
    }, // eslint-disable-next-line
    []
  );

Upvotes: 3

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