JSON 来自 URL 的数组 DELPHI

Question

我有以下 Json 来自 url link 的数组。

[{"DATE":"01/10/2021","QUANTITY":4,"UNITPRICE":23.9}, 
 {"DATE":"01/10/2021","QUANTITY":5.85,"UNITPRICE":23.9}, 
 {"DATE":"30/09/2021","QUANTITY":10,"UNITPRICE":23.9}, 
 {"DATE":"04/08/2021","QUANTITY":10,"UNITPRICE":28.83}, 
 {"DATE":"01/07/2021","QUANTITY":1,"UNITPRICE":2.06}, 
 {"DATE":"01/07/2021","QUANTITY":1,"UNITPRICE":2.06}, 
 {"DATE":"30/06/2021","QUANTITY":1,"UNITPRICE":2.06}, 
 {"DATE":"30/06/2021","QUANTITY":1,"UNITPRICE":2.06}]

我想从上面的 JSON 结构中提取数据，然后在 Memo 或 ListView 中显示它。

创建一个 Json 数组并将数据放入其中是否正确？当我运行我的代码并单击按钮时，它没有显示任何内容。另外，我是 Delphi.

的新手

这是我写的代码：

function GetURLAsString(const aurl: string): string;
var
  IdHTTP1 : TidHTTP;
begin
  IdHTTP1 := TIdHTTP.Create(nil);
  try
    IdHTTP1.IOHandler := TidSSLIOHandlerSocketOpenSSL.Create(IdHTTP1);
    Result := IdHTTP1.Get(aurl);
  finally
    IdHTTP1.Free;
  end;
end;

procedure TForm4.Button1Click(Sender: TObject);
var
  jso : TJsonObject;
  js : TJsonObject;
  jsv : TJsonValue;
  jsa : TJsonArray;
  jsp : TJsonPair;
  data : string;
  i : integer;
  LItem : TListViewItem;
begin
  try
    data := GetURLAsString('http://....');
  except
    on E: exception do
  end;

  try
    jsv := TJSONObject.ParseJSONValue(data);
    try
      jso := jsv as TJSONObject;
      jsa := TJSONArray.Create();
      jsp := TJSONPair.Create('Array', jsa);
      js.AddPair(jsp);
      jsp := jso.Get('Array');
      jsa := jsp.JsonValue as TJsonArray;
      for I  := 0 to jsa.Size - 1 do
      begin
        jso := jsa.Get(i) as TJsonObject;

        for jsp in jso do
        begin
          if jsp.JsonString.Value  = 'DATE' then
          begin
            form4.ListView1.BeginUpdate;
            LItem := form4.ListView1.Items.Add;
            LItem.Text := jso.GetValue('DATE').ToString;
            form4.ListView1.EndUpdate;
          end;
        end;
      end;
    finally
      jsv.Free;
    end;
  except
    on E: exception do
  end;
end;

Answer 1

我怀疑你会遇到访问冲突，因为你访问了未初始化的js变量的AddPair方法，由于你捕获了异常并忽略了它，所以你没有看到它。

但是，您使解决方案过于复杂，这会导致错误。这应该有效：

jsa := jsv as TJSONArray;
form4.ListView1.BeginUpdate;
try
 for I  := 0 to jsa.Size - 1 do
    begin
       jso := jsa.Get(i) as TJsonObject;
       LItem := form4.ListView1.Items.Add;
       LItem.Text := jso.GetValue('DATE').ToString;
    end;

 finally
  form4.ListView1.EndUpdate;
 end;
finally
  jsv.Free;
end;

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