CODEWITHSUNDEEP
javascriptreactjsmongodb
Sr New
Sr New

Reputation: 77

Data retrival and assignment in Reactjs

I am running Reactjs and mongdb. In Reactjs, once user selects the value, I am sending that into mongob

addTodo(event) {
        event.preventDefault();
        var roomID = this.state.selectedRoomID;
         console.log(RoomID); //This value is printed correctly

        const { mongodb } = this.props;
        mongodb.db("attendance")
            .collection("MasterDB").find({"RoomID": roomID}).asArray()
            .then(MasterDB => {
                this.setState({ MasterDB }); console.log("inside"+this.state.MasterDB.length);
            });
        console.log("outside"+this.state.MasterDB.length)

a) Here first console.log is printing correctly. b) when ever I do find with roomID=1 explicitly the Query method is working. whenever I keep roomID=this.state.selectedRoomID;. Query is not working because roomID is not getting any value. I am not sure why it is not getting that value. c) When I execute I see, console.log(outside) is printed first and than console.logg(inside) is printed.

As this is sequential, I am expecting the order other way. is there a way I can make sure first the lookup in mongodb happens first that is (console.log(inside) is printed first followed by console.log(outside)?

I see this as issue with reactjs the way I am sending the variables

Upvotes: 1

Views: 68

Answers (1)

Lavanya Ravi
Lavanya Ravi

Reputation: 56

I need to look at the code when selectedRoomID is set to figure out why it is not getting any value.

As for the code to execute synchronously, either use Promises or Async/Await. That should help you run the code in the way you want it.

For example, in the code you posted, if you put the console log statement inside the then function, it should work fine. Or you can make the whole mongodb command a promise and wait for it to finish before proceeding further.

Upvotes: 4

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