B4J Tutorial [BANano] Checking File Existence : (Async Fetch - BANanoFetch Inside BANanoPromise)

Hi

This code is based on a response I got about something else I needed about files, fetch & promise.

Anyway.. The code below will check if a file exists and return true / false. I need the file check to trap & report an error if the file does not exist.

private Sub FileExist(fn As String) As Boolean
    Dim error As Object
    Dim fetch As BANanoFetch
    Dim fetchResponse As BANanoFetchResponse
    Dim prom As BANanoPromise
      '
    Dim bfo As BANanoFetchOptions
    bfo.Method = "HEAD"
    
    '_prom = new Promise(function(resolve,reject) {
    prom.NewStart
    '_fetch=fetch(_fn,_bfo);
    fetch.Initialize(fn, bfo)
    '_fetch.then(function(_fetchresponse) {
    fetch.Then(fetchResponse)
    'resolve(_fetchresponse.ok);
    BANano.ReturnThen(fetchResponse.OK)
    '}).catch(function(_error) {
    fetch.Else(error)
    'reject(false);
    BANano.ReturnElse(False)
    '});
    fetch.End
    '});
    prom.NewEnd
      
    '_res=await _prom;
    Dim res As Boolean = BANano.Await(prom)
      Return res
End Sub

Usage - checking a file on assets directory.

Dim fe As Boolean = BANano.Await(FileExist("./assets/dbFile.sql"))

Have Fun.