B4J Tutorial [BANano] The Logic of Loading AutoComplete Input from API with BANanoFetch at runtime


Whilst this is being tested with BANanoVueMaterial, the LOGIC is applicable for any related code like this. We are loading an autocomplete input based of a fetch results from a github repo of public API. The qualifier is the code logic. You can trap the input event of your autocomplete to achieve the same..


1. When our app runs, our autocomplete is empty
2. Each type a user types something, we detect a few things, (a) is the autocomplete filled already and (b) is it loading
3. If the autocomplete is already filled exit the reload and if its loading exit the reload else load it.
4. The SearchItems sub can then be fed the results of your autocomplete input detection and the Fetch happens


Sub SearchItems(xval As String)
    'get the already existing list of items
    Dim items As List = vm.GetState("itemsa", Array())
    'get the loading status
    Dim isloading As Boolean = vm.GetState("isloading",False)
    'items already loaded
    If items.Size > 0 Then Return
    'items have been requested
    If isloading Then Return
    'change the state to loading
    vm.SetStateSingle("isloading", True)
    ' do the search
    Dim Response As BANanoFetchResponse
    Dim Data As BANanoJSONParser
    Dim Error As BANanoJSONParser
    ' list (GET is default, and we do not need extra options so we pass Null for the options)
    Dim fetch1 As BANanoFetch
    'execute the fetch
    fetch1.Initialize("https://api.publicapis.org/entries", Null)
    'we got a promise response
    ' so resolve it to a json
        Dim res As Map = Data.NextObject
        Dim count As Long = res.Get("count")
        Dim entries As List = res.Get("entries")
        'lets build up our items
        Dim items As List
        'we define how long a description should be
        Dim dl As Int = vm.GetState("descriptionlimit",descriptionlimit)
        'get the entries and limit the description to specified length
        For Each entry As Map In entries
            Dim sDescription As String = entry.Get("Description")
            If sDescription.Length > descriptionlimit Then
                sDescription = vm.LeftString(sDescription, dl) & "..."
                entry.Put("Description", sDescription)
            End If
        'save the list of items to load to the auto-complete
        vm.SetStateSingle("itemsa", items)
        'turn the loading state to false
        vm.SetStateSingle("isloading", False)
End Sub

In our case, when the "itemsa" state changes after a load, the autocomplete is loaded automatically with new content. That is where BANano specific code can come in to load your autocomplete.

After everything is loaded, of course,the isloading is made false.

One of the interesting things is getting the details of a selected API. On the list of items listed, each is saved as an object. So on click of the autocomplete, the selected object is read and a key, value pair list is made. Ours is called a "model"

Sub ComputeFields As List
    Dim fields As List
    Dim model As Map = vm.GetState("model",Null)
    If model = Null Then Return fields
    For Each k As String In model.Keys
        Dim v As Object = model.Get(k)
        fields.Add(CreateMap("key": v, "value":v))
    vm.SetStateSingle("fields", fields)
    Return fields
End Sub