B4J Question [BANano] [SOLVED] Please help with List.sortType for sorting a list of maps.

[Mashiane]

Hi

I've just found this good piece of code that I want to apply in sorting my lists of maps?

Type SortHelper(SortKey As String, Value As Object) 'add in Process_Globals

Sub SortListOfArrays(Table As List, Index As Int) As List
   Dim temp As List
   temp.Initialize
   For Each row() As String In Table
      Dim sh As SortHelper
      sh.SortKey = row(Index)
      sh.Value = row
      temp.Add(sh)
   Next
   temp.SortType("SortKey", True)
   Table.Clear
   For Each sh As SortHelper In temp
      Table.Add(sh.Value)
   Next
   Return Table
End Sub

By Erel from here

Sorting algorithms - Teaching with Basic4android

Implementations of sorting algorithms are useful for teaching fundamental concepts such as algorithms analysis, complexity and data structures. The following code includes implementations of the following sorting algorithms: bubble sort, selection sort, quick sort, merge sort and binary tree...

www.b4x.com

I have tweaked it so that I can do the same for a list of maps.

Sub ListOfMapsSort(lst As List, orderBy As String) As List
    Dim fields As List
    fields.Initialize
    For Each fldm As Map In lst
        Dim sname As String = fldm.Get(orderBy)
        Dim sh As SortHelper
        sh.Initialize 
        sh.SortKey = sname
        sh.Value = fldm
        fields.Add(sh)
    Next
    fields.SortType("SortKey", True)
    Dim sorted As List
    sorted.Initialize
    For Each sh As SortHelper In fields
        sorted.Add(sh.Value)
    Next
    Return sorted
End Sub

The compiled code

// [4768] Sub ListOfMapsSort(lst As List, orderBy As String) As List 
this.listofmapssort=function(_lst,_orderby) {
if (_B==null) _B=this;
var _fields,_fldm,_sname,_sh,_sorted;
// [4769]     Dim fields As List 
_fields=[];
// [4770]     fields.Initialize 
_fields.length=0;
// [4771]     For Each fldm As Map In lst 
for (var _fldmindex=0;_fldmindex<_lst.length;_fldmindex++) {
_fldm=_lst[_fldmindex];
// [4772]         Dim sname As String = fldm.Get(orderBy) 
_sname=_fldm[_orderby];
// [4773]         Dim sh As SortHelper 
_sh=(typeof banano_sithasodaisy_sorthelper === 'function') ? new banano_sithasodaisy_sorthelper(): null;
// [4774]         sh.Initialize 
_sh.initialize();
// [4775]         sh.SortKey = sname 
_sh._sortkey=_sname;
// [4776]         sh.Value = fldm 
_sh._value=_fldm;
// [4777]         fields.Add(sh) 
_fields.push(_sh);
// [4778]     Next 
}
// [4779]     fields.SortType( {2219} , True) 
if (!isNaN(parseFloat(_fields[_fields.length-1]["_SortKey"])) && isFinite(_fields[_fields.length-1]["_SortKey"])) {
_fields.sort(function(a, b){return a["_SortKey"] - b["_SortKey"]});
} else {
_fields.sort(function (a, b) {return a["_SortKey"].localeCompare(b["_SortKey"]);});
};
// [4780]     Dim sorted As List 
_sorted=[];
// [4781]     sorted.Initialize 
_sorted.length=0;
// [4782]     For Each sh As SortHelper In fields 
for (var _shindex=0;_shindex<_fields.length;_shindex++) {
_sh=_fields[_shindex];
// [4783]         sorted.Add(sh.Value) 
_sorted.push(_sh._value);
// [4784]     Next 
}
// [4785]     Return sorted 
return _sorted;
// End Sub
};

Its raising an error on this line

_fields.sort(function (a, b) {return a["_SortKey"].localeCompare(b["_SortKey"]);});

Error

TypeError: Cannot read properties of undefined (reading 'localeCompare')

Thank you in advance.

 

[alwaysbusy]

Try fields.SortType("sortkey", True) 'lowercase