Delphi 生成前端TreeView Json数据

前面的树形图，也就是TreeView一般读取的都是Json数据

例如

[{dispCode:01,dispName:'上级1, children: [

      {dispCode:0101,dispname:'子级1' },

      {dispCode:0102,dispname:'子级2' },

    ]

}]

下面代码，读取的数据表里需要有以下字段 

DispCode：编码 DispName：名称  level_num：级次

实现思路是先生成一个个对象（TeleItem），再将对象转化成JSONObject对象，再输出JSON文本。

可以调用REs.jSON里的TJson.ObjectToJsonString直接生成JSON文本，但是他会给输入增加一个Name叫XXXhelper。不是我要的。所以最终只能先自行将

TeleItem生成JSONObject再将jsonobjct生成Jsonobject。

Teleitem

实现代码

unit UntTree;

interface
uses System.Generics.Collections, FireDAC.Comp.Client,JSON,REST.Json,System.SysUtils;
type
  TeleItem=class
    dispcode:string;    //编码
    dispName:String;      //名称
    level_num:integer;     //级次
    children:TList<Teleitem>;    //子级
    destructor Destroy; override;

  end;


function IntTree(FDQuery:TFDQuery;tableName,SetCode:String):String;    //方法1  先生成Teleitem再生成Jsonobject
function LoadEleTree(FDQuery:TFDQuery;tableName,SetCode:String):String;    //方法2 直接生成Jsonobject

implementation
function LoadEleTree(FDQuery:TFDQuery;tableName,SetCode:String):String;
var
 FJOlist:TList<TJSONObject>;
 FJData:TJSONObject;
 I,levelnum,J:integer;
 cDispCode:string;
 JOParent,JO:TJsonObject;
 JaData,Children:TJSONArray;
 begin
  FJData:=TJsonObject.Create;
  FJOlist:=TList<TJSONObject>.Create;
  JaData:=TJSONArray.Create;
  FJData.AddPair('data',JaData);
  FDQuery.Close;
  FDQuery.open('select * from '+tableName +' where set_Code='''+setCode+''' and is_leaf<>10');
  FDQuery.FetchAll;
  while Not FDQuery.Eof do
   begin
     try
        JO:=TJSONObject.Create;
       J:=FDQuery.FieldByName('level_num').AsInteger;
       cDispCode:=FDQuery.FieldByName('disp_Code').asstring;
       JO.AddPair('DispCode',cdispCode);
       JO.AddPair('DispName',FDQuery.FieldByName('disp_Name').asstring);
       JO.AddPair('LevelNum',INTTOSTR(J));

       FJOlist.Add(JO);
        if FDQuery.FieldByName('level_num').asinteger<>1 then
           begin
             for  I := 0 to FJOlist.Count-1 do
              begin
               JOParent:=FJOlist[I];
               levelnum:=JOParent.Values['LevelNum'].Value.tointeger;
              if levelnum+1<>J then Continue;
                var dispCode:=JOParent.Values['DispCode'].Value;
                if Pos(dispcode,cdispCode)=1 then
                 begin
                   if not Assigned(JOParent.Values['Children']) then
                     begin
                       Children:=TJSONArray.Create;
                       JOParent.AddPair('Children',Children);
                     end else
                     Children:=JOParent.Values['Children'] as TJSONArray;
                   Children.Add(JO);
                   break;
                 end;
              end;
           end else
         JaData.Add(JO);
     finally
       FDQuery.Next;
     end;
   end;
  Result:=FJData.ToJSON();
  FJData.Free;
  FJOlist.Free;
 end;
function IntTree(FDQuery:TFDQuery;tableName,SetCode:String):String;
var
  I:integer;
  dispcode:String;
  Data:TJSONObject;
  FList,FTree:TList<TeleItem>;
   {$REGION 'ConvertToObject'}
    procedure ConvertToObject(Item:Teleitem;var Perent:TJSONArray);
    var
     aItem:TJSONObject;
     I:Integer;

     begin
      aitem:=TJSONObject.Create;
      aitem.AddPair('dispcode',item.dispcode);
      aitem.AddPair('dispname',item.dispname);
      Perent.add(aitem);
      IF Not Assigned(Item.children) then Exit;
      var P:=TJSONArray.Create;
      aitem.AddPair('children',P);
      For I:=0 to item.children.count-1 do
       begin
         ConvertToObject(item.children[I],P);
       end;

     end;
   {$ENDREGION 'ConvertToObject'}
 begin
    FDQuery.Close;
    FDQuery.open('select * from '+tableName +' where set_Code='''+setCode+''' and is_leaf<>10');
    FDQuery.FetchAll;
    FList:=TList<Teleitem>.create;
    FTree:=TList<Teleitem>.create;
    while Not FDQuery.eof do
     begin
       try
         Var AEle:=TEleitem.create;
            aEle.dispCode:=FDQuery.FieldByName('disp_Code').asstring;
            aele.dispName:=FDQuery.fieldByName('disp_Name').asstring;
            AEle.level_num:=FDQuery.FieldByName('level_num').asinteger;
            FList.Add(AEle);
            if FDQuery.FieldByName('level_num').asinteger<>1 then
             begin
               for I := 0 to Flist.Count-1 do
                begin
                if Flist[I].level_num+1<>AEle.level_num then Continue;
                  dispCode:=Flist[I].dispCode;
                  if Pos(dispcode,aEle.dispCode)=1 then
                   begin
                     if not Assigned(Flist[I].children) then
                       Flist[I].children:=TList<Teleitem>.create;
                     FList[I].children.Add(aele);
                     break;
                   end;

                end;
              end else
              FTree.Add(Aele);
       finally
         FDQuery.Next;
       end;
     end;

    Data:=TJSONObject.create;
    var P:=TJSONArray.Create;
    data.AddPair('data',P);
    for I := 0 to FTree.Count-1 do
     begin
      ConvertToObject(FTree[I],P);
     end;
   Result:=data.ToJSON();
   data.Free;
   for I :=FList.count-1 downto 0 do
    begin
      Flist[I].Free;
    end;
    FList.Free;
    FTree.Free;
 end;
{ TeleItem }

destructor TeleItem.Destroy;
begin
  if Self.children<>nil then
    Self.children.Free;
end;

end.

最终的结果如下，是一个json文本，然后前端如何生成Tree，自行研究