gRPC

[Yasaswini Gadde]

can you please provide me gRPC document on React Native. 

[Nicolas Noble]

These two things have very little in common. One is a RPC system, the other is a UI system. There's not really anything we have off the shelve we could share with you that talks about both specifically. What would you be looking for exactly?

[Yasaswini Gadde]

Hi sir, we are used  grpc-web package in react native for developing mobile application. When I am calling a 

GetBook() function . it is running linearly up to line number 17 then suddenly it is jumping line number 31 and after executing remaining lines control is moving to line 18 and calling grpc unary function. In line 26 bookTitle variable is showing a value but  In  line number 27 when we are trying to  return it ,  it is showing  undefined. Please help us

[Jeff Steger]

I dont know react. But this problem almost certainly has nothing to do with grpc. It probably has to do with either the nature of variable scoping in react or (more probably) the lifetime of the message object (and assignment sematics in react). You need React expertise, not grpc expertise. 

On Sat, Feb 6, 2021 at 8:56 AM Yasaswini Gadde <yasaswin...@gmail.com> wrote:

Hi sir, we are used  grpc-web package in react native for developing mobile application. When I am calling a 

GetBook() function . it is running linearly up to line number 17 then suddenly it is jumping line number 31 and after executing remaining lines control is moving to line 18 and calling grpc unary function. In line 26 bookTitle variable is showing a value but  In  line number 27 when we are trying to  return it ,  it is showing  undefined. Please help us

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[Nicolas Noble]

Your problem is you need to read up on asynchronous programming in JavaScript, such as https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous/Introducing

The grpc_web call is setting up a callback, and the reason the code jumps around is that the code isn't being run yet. It will be executed at a later time when the RPC finishes.

You can reproduce the same issue without grpc using the following code:

```javascript

function getBook() {

  var bookTitle;

  setTimeout(0, () => {

    bookTitle = "Hello World";
    console.log(bookTitle);

  });
  console.log(bookTitle);

  return bookTitle;
}
```

Here, the callback set in the timeout function will be called after getBook returns.

You need to modify your code to make it asynchronous. The same problem would arise with any other asynchronous javascript library.

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