delphi c++builder JSON 生成与解析 例子

json，System.JSON,REST.JSON

JSON有两种数据结构，对象和数组。

对象在js中表示为“{}”括起来的内容，数据结构为 {key：value,key：value,...}

数组在js中是中括号“[]”括起来的内容，数据结构为 ["java","javascript","vb",...]

{
"NAME":"DVAD",
"SEX":"MAN",
"AGE":12
}

{"success":true}

"{\"success\":true}"

https://community.embarcadero.com/blogs/entry/how-to-make-restful-webbroker-using-c-builder

jo用完记得释放 jo.free;

root['child.name']

http://docwiki.embarcadero.com/Libraries/Berlin/en/System.JSON.TJSONObject

一、 System.Json.Readers  JSONWriter

System.Json.Readers,System.Json.Writers,  System.Json.Types

TJsonReader\TJsonTextWriter,与.net的Newtonsoft JsonTextReader 、JsonTextWriter相同，是RAD10 Settle版新增的功能。
http://docwiki.embarcadero.com/CodeExamples/Berlin/en/RTL.JSONWriter

System.JSON.Writers.hpp

生成的json字符串

{
  "id": "001",
  "name": "aaa",
  "age": 99
}

procedure TFrmLogin.Button2Click( Sender : TObject );
  var
    writer : TJsonTextWriter;
    sw : TStringWriter;
  begin
    sw := TStringWriter.Create;
    writer := TJsonTextWriter.Create( sw );
    writer.Formatting := TJsonFormatting.Indented;
    writer.WriteStartObject;
    writer.WritePropertyName( 'id' );
    writer.WriteValue( '' );
    writer.WritePropertyName( 'name' );
    writer.WriteValue( 'aaa' );
    writer.WritePropertyName( 'age' );
    writer.WriteValue(  );
    writer.WriteEndObject;

    self.Memo1.Text := sw.ToString;
    sw.Free;

  end;

相比较JSONBuilder更清晰，吸收了java的优点。java参考 http://docs.oracle.com/javaee/7/api/javax/json/JsonObjectBuilder.html

http://docwiki.embarcadero.com/CodeExamples/Seattle/en/RTL.JSONBuilder

http://docwiki.embarcadero.com/CodeExamples/Berlin/en/RTL.JSONBuilder

uses
  System.SysUtils,
  System.Classes,
  System.JSON.Types,
  System.JSON.Writers;
  System.JSON.Builders;

var
  Builder: TJSONObjectBuilder;
  Writer: TJsonTextWriter;
  StringWriter: TStringWriter;
  StringBuilder: TStringBuilder;

begin
  StringBuilder := TStringBuilder.Create;
  StringWriter := TStringWriter.Create(StringBuilder);
  Writer := TJsonTextWriter.Create(StringWriter);
  Writer.Formatting := TJsonFormatting.Indented;
  Builder := TJSONObjectBuilder.Create(Writer);

  Builder
    .BeginObject
      .BeginArray('Transaction')
        .BeginObject.Add('id', )
          .Add('firstName', 'John')
          .Add('lastName', 'Doe')
          .Add('price', 2.1)
          .AddNull('parent_id')
          .Add('validated', true)
        .EndObject
        .BeginObject
          .Add('id', )
          .Add('firstName', 'Anna')
          .Add('lastName', 'Smith')
          .Add('price', 4.5)
          .AddNull('parent_id')
          .Add('validated', false)
        .EndObject
        .BeginObject
          .Add('id', )
          .Add('firstName', 'Peter')
          .Add('lastName', 'Jones')
          .Add('price', 3.6)
          .AddNull('parent_id')
          .Add('validated', true)
        .EndObject
      .EndArray
    .EndObject;

  WriteLn(StringBuilder.ToString);

生成的json字符串

{"Transaction":[
  {"id":662713, "firstName":"John", "lastName":"Doe", "price": 2.1, "parent_id": null, validated:true},
  {"id":662714, "firstName":"Anna", "lastName":"Smith", "price": 4.5, "parent_id": null, validated: false},
  {"id":662715, "firstName":"Peter", "lastName":"Jones", "price": 3.6, "parent_id": null, validated: true}
  ]}

二、System.JSON.pas

System.JSON.pas
#include <System.JSON.hpp>

  TJSONArray* jar = (TJSONArray*)TJSONObject::ParseJSONValue(Memo3->Text);
    jar->Count;
    for (int i = ; i < jar->Size(); i++)
    {

        TJSONValue *jv = jar->Get(i);
        jv = ((TJSONArray*)jv)->Get();
        TJSONPair *jp = (TJSONPair*)jv;
        jp->JsonString->Value();//值字段名
        jp->JsonValue->Value();//取值
        if (jp->JsonValue->Value() == "") // 判断值
        {
            jar->Remove(i);
            break;
        }
    }
    // jar->Remove(1);
    Memo3->Text = jar->ToString();

    delete jar;

TJSONObject *JSON = (TJSONObject*)TJSONObject::ParseJSONValue(Memo2->Text);

TJSONArray* jArray = (TJSONArray*)JSON->Get("adverts")->JsonValue;

jar->Items[0]->Value();

TJSONObject* jCompanyInfo = (TJSONObject*)((TJSONObject*)jArray->Get(0))->Get("companyInfo")->JsonValue;
 String companyName = jCompanyInfo->Get("companyName")->JsonValue->Value();

• 自己测试的例子

[
 {
 "cmd":32,
 "error":"",
 "data":[
 {"cp":"xx1", "js":"5124", "jsqwz":"xxx1","b":"2012"},
 {"cp":"xx2", "js":"5124", "jsqwz":"xxx2","b":"2013"},
 {"cp":"xx3", "js":"5124", "jsqwz":"xxx3","b":"2014"}
 ]
 }]

    TJSONObject *JSON = (TJSONObject*)TJSONObject::ParseJSONValue(Memo4->Text);
    JSON = (TJSONObject*)JSON->Get();
    JSON->Count;
    ((TJSONPair*)JSON->Get("cmd"))->JsonString->Value();
    ((TJSONPair*)JSON->Get("cmd"))->JsonValue->Value();

    ((TJSONPair*)JSON->Get("error"))->JsonString->Value();
    ((TJSONPair*)JSON->Get("error"))->JsonValue->Value();

    TJSONArray *jar = (TJSONArray*) jo->Get("data")->JsonValue;
    //TJSONArray *jar = (TJSONArray*)((TJSONPair*)JSON->Get("data")->JsonValue);
    for (int i = ; i < jar->Count; i++)
    {

        for (int j = ; j < ; j++)
        {
            Caption = ((TJSONPair*)((TJSONArray*)jar->Get(i))->Get(j))->JsonString->Value();
            Caption = ((TJSONPair*)((TJSONArray*)jar->Get(i))->Get(j))->JsonValue->Value();
        }

    }

 delphi写法

  jo := jv as TJSONObject;
  jar := jo.GetValue('Column') as TJSONArray;

  for I :=  to jar.Count -  do
  begin
    jar.Get(I) as TJSONValue).Value;
  end;

  jar := jo.GetValue('data') as TJSONArray;
  for I :=  to jar.Count -  do
  begin

    jo := jar.Get(I) as TJSONObject;   

      Caption := jo.Values['cp'].Value; // value字段名访问 (1)

    Caption := jo.GetValue('cp').Value;// getvalue 字段名访问(2)
    Caption =jo.getValue('cp','');

    // jv := jar.Get(I);
    // Caption := jv.GetValue('cp', '');
    //
    for j :=  to jo.Count -  do
    begin
      Caption := jo.Pairs[j].JsonValue.Value; // Pairs 索引遍历访问 (3)
      Caption := jo.Values[jo.Pairs[j].JsonString.Value].Value; // Values索引遍历访问(4)

    end;
    // Break;
  end;

生成json

TJSONObject *OBJ = new TJSONObject();
 OBJ->AddPair("Result", "1");
 OBJ->AddPair("Text", "密码不正确");

OBJ->AddPair("DATA", jsonArray);//这样也可以
 Memo5->Text = OBJ->ToString(); //OBJ->ToString();  ToJSON

#include "Data.DBXJSONCommon.hpp"

TDBXReader *reader;

TJSONObject *jsobj=TDBXJSONTools::TableToJSON(reader,10,true);

String jsstr=jsob.ToString

arr: TJSONArray;
arr := TJSONObject.ParseJSONValue(TEncoding.UTF8.GetBytes(''), 0) as TJSONArray;

FClient: TRESTClient;
    FRequest: TRESTRequest;
    FDataSets: TFDJSONDataSets;

LJSONObj := FRequest.Response.JSONValue.GetValue<TJSONArray>('result').Items[0] as TJSONObject;

jsonValue->GetValue<String>("rID")

LUnmarshaller := TJSONUnMarshal.Create;
   FDataSets := LUnmarshaller.Unmarshal(LJSONObj) as TFDJSONDataSets;

三、delphi 最常用最简单的json解析

{"Work":"err","Plan":"err"}

1）用TJSONValue解析

TJSONValue ToJSON和ToString的区别。

TJSONString  System.JSON.pas

jv.ToJSON  、汉字是Unicode符号\xxxx，有转移字符，例如/ 转出json串 \/,传输比较安全，语法正确。

jv.ToString   汉字是真实的汉字，无需转换，但是多了\，需要删除处理，没有转移字符会报错。

jv.Value ： 汉字是真实的unicode，没有多余的\，直接使用。

delphi json 汉字 Unicode编码说明.

procedure TForm22.Button1Click(Sender: TObject);
var
  jv: TJSONValue;
begin
  jv := TJSONObject.ParseJSONValue(self.Memo1.Text);
  self.Caption := jv.GetValue('Work', '');
  jv.GetValue('Plan', '');

end;

str:=  jo.GetValue('result.token','');
str:=  jo.GetValue<string>('result.token');
jarr := jo.GetValue<TJSONArray>('result.list') ;

带路径path获取json值。方便的json，推荐，这些就省得一层一层转换了。

str := jo.GetValue<TJSONArray>('data.List').Get(0).Value;

yue := jo.GetValue<TJSONArray>('data.CardList').Get(0).GetValue<string>('balance').ToDouble();

2）用TJSONObject也可以。

procedure TForm1.Button3Click(Sender: TObject);
var
  jo: TJSONObject;
begin
  jo := TJSONObject.ParseJSONValue(self.Memo1.Text) as TJSONObject;
  self.Caption := jo.GetValue('Success', '');
  jo.GetValue('Plan', '');
end;

//delphi 语法 json A节点下B的值

jo.Values['responseInfo'].GetValue('isSuccess', '');

jo.Get('Name').JsonValue.Value

TJSONString(ja.Get(0)).Value;

 C++语法

jo->Values["aname"];

jo->Values["aname"]->Value();

jv->GetValue<String>("aname");

TJSONObject *jo = (TJSONObject*)TJSONObject::ParseJSONValue(Memo1->Text);
    this->Caption = jo->Values["code"]->Value();
    this->Caption = jo->Values["code"]->ToJSON();
    this->Caption = jo->Values["code"]->ToString();

参考万老师

http://www.cnblogs.com/del/p/4225871.html

http://docwiki.embarcadero.com/CodeExamples/Seattle/en/RTL.JSONReader

"{"responseInfo":{"isSuccess":"-","errMsg":"设备连接异常"}}"

TStringReader *sr = new TStringReader(out);
TJsonTextReader * reader = new TJsonTextReader(sr);
reader->Read();
reader->Read();
reader->Read();
reader->Read();
reader->TokenType;
reader->Path;
String www = reader->Value.ToString();
String aaa = reader->ReadAsString();

TJSONObject *JSON = (TJSONObject*)TJSONObject::ParseJSONValue(String(out));

TJSONArray *jar =  (TJSONArray*) JSON->Get("responseInfo")->JsonValue;

jar->Count;//

TJSONPair *jp= (TJSONPair*) jar->Get();
aaaaaa= jp->JsonString->Value();//isSuccess
aaaaaa= jp->JsonValue->Value();//-1

http://stackoverflow.com/questions/14864170/how-to-parse-a-json-array-in-rad-studio

RAD10，很多资料

http://www.cnblogs.com/HuiLove/p/4006248.html

http://community.embarcadero.com/blogs/entry/learn-how-to-use-the-new-json-features-in-rad-studio-10-seattle-webinar-march-2nd-wednesday

Delphi JSON Viewer (executable): http://cc.embarcadero.com/Item/30495 树形查看器

LJSONObject: TJSONObject;

LJSONObject := TJSONObject.ParseJSONValue(MemoJSONUser.Text) as TJSONObject;

JSONObject.Values['name'].ToString

LJSONValue:   TJSONValue;
LPair:  TJSONPair;
  LJSONValue := TJSONObject.ParseJSONValue(BytesOf(E.ResponseText), );

  if LJSONValue is TJSONObject then
  begin

    LPair := TJSONObject(LJSONValue).Get();

    if LPair.JsonString.Value = 'SessionExpired' then
      // Clear session id because it is no good
      AConnection.SessionID := '';
    // Extract error message
    LMessage := LPair.JSONValue.Value;

  end;

  LAcctType := TJSONArray(LPair.JSONValue).Get().Value;
  LAcctName := TJSONArray(LPair.JSONValue).Get().Value;
  LAcctKey := TJSONArray(LPair.JSONValue).Get().Value;

jo: TJSONObject;

str:=jo.Get('ResultValue').JsonValue.GetValue('Total','');

iaint:=jo.Get('ResultValue').JsonValue.GetValue('Total','').ToInteger;

svalue = jo->GetValue("data")->GetValue<String>("token", "");//c++

嵌套JSON下面这2种都可以。

{

"time": "2016-06-24 08:07:40",

"data": {

"token": "4a414be399650d68e010bdb366790f78",

"validTime": "288000"

}

}

self.Caption := jo.Get('data').JsonValue.GetValue('token', '');
  self.Caption := jo.GetValue('data').GetValue('token','');

TJsonToken = (
    None,
    StartObject,
    StartArray,
    StartConstructor,
    PropertyName,
    Comment,
    Raw,
    Integer,
    Float,
    &String,
    Boolean,
    Null,
    Undefined,
    EndObject,
    EndArray,
    EndConstructor,
    Date,
    Bytes,
    // Extended JSON
    Oid,
    RegEx,
    DBRef,
    CodeWScope,
    MinKey,
    MaxKey
  );

三、REST.JSON.pas

 

TJson.JsonToObject
TJson.ObjectToJsonString

JsonEncode

ObjectToJsonObject

json序列化与反序列化

 

 http://docwiki.embarcadero.com/RADStudio/Seattle/en/Serializing_User_Objects

 

2016.4.29 RAD Berlin 最新版 json改进

http://docwiki.embarcadero.com/RADStudio/Berlin/en/What's_New#Modified_JSON_Path_Syntax_to_Access_Object_Properties

 

{
    "P_TYPE" : "2",
    "PatientID" : "0000023561",
    "LISTNO" : "2353",
    "PIC_DATA" : [{
            "PIC_ID" : "1",
            "data" : "111111111111"
        }, {
            "PIC_ID" : "2222222222222222",
            "data" : ""
        }, {
            "PIC_ID" : "333333333333333333333",
            "data" : ""
        }
    ]
}

 

    TJSONObject *OBJ = new TJSONObject();
    OBJ->AddPair("AA", "");
    OBJ->AddPair("BB", "");
    OBJ->AddPair("CC", "");

    TJSONArray *arr;
    arr = new TJSONArray();

    TJSONObject *jv = new TJSONObject();
    jv->AddPair("PIC_ID", "");
    jv->AddPair("data", (""));
    arr->AddElement(jv);

    jv = new TJSONObject();
    jv->AddPair("PIC_ID", "");
    jv->AddPair("data", (""));
    arr->AddElement(jv);

    jv = new TJSONObject();
    jv->AddPair("PIC_ID", "");
    jv->AddPair("data", (""));
    arr->AddElement(jv);

    OBJ->AddPair("PIC_DATA", arr);

 

TJSONValue的值

TDBXCallback的Execute(const Arg: TJSONValue): TJSONValue;

 

 

["abc",123,true]

没有名字，仅有值的json，创建数字，bool，字符串类型的json值

var
  ja: TJSONArray;
begin
 ja := TJSONArray.Create;
 ja.AddElement(TJSONString.Create('abc'));
 ja.AddElement(TJSONNumber.Create());
 ja.AddElement(TJSONBool.Create(true));

Memo1.Text:= ja.ToString;

{"name":"james","age":38,"marry":true}有名称的值。

var
jo:TJSONObject;
begin
jo := TJSONObject.Create;
jo.AddPair('name',TJSONString.Create('james'));
jo.AddPair('age',TJSONNumber.Create());
jo.AddPair('marry',TJSONBool.Create(true));

self.Memo1.Text:=jo.ToString;

["abc",123,true,{"book":"james","bank":38,"phone":true}]

var
  ja: TJSONArray;
  jo: TJSONObject;
begin
  ja := TJSONArray.Create;
  ja.AddElement(TJSONString.Create('abc'));
  ja.AddElement(TJSONNumber.Create());
  ja.AddElement(TJSONBool.Create(true));

  jo := TJSONObject.Create;
  jo.AddPair('book', TJSONString.Create('james'));
  jo.AddPair('bank', TJSONNumber.Create());
  jo.AddPair('phone', TJSONBool.Create(true));

  ja.AddElement(jo);

  //ja.Add(jo);

jo.AddPair('ret',TJSONNull.Create);

jo := TJSONObject.Create(TJSONPair.Create('game','nba'));

 

 

  ja := TJSONArray.Create;
  ja.AddElement(TJSONString.Create('james'));
  ja.AddElement(TJSONNumber.Create(38));

Arg：=ja 或者 Arg :=  TJSONNumber.Create(38);

http://docwiki.embarcadero.com/Libraries/Berlin/en/System.JSON.TJSONNumber.Create

 

class function TNoteJSON.JSONToNotes(const AJSON: TJSONArray): TArray<TNote>;
var
  LValue: TJSONValue;
  LList: TList<TNote>;
begin
  LList := TList<TNote>.Create;
  try
    for LValue in AJSON do
      LList.Add(TNoteJSON.JSONToNote(LValue));
    Result := LList.ToArray;
  finally
    LList.Free;
  end;
end;

json迭代器TJSONIterator

http://docwiki.embarcadero.com/CodeExamples/Berlin/en/RTL.JSONIterator

LIterator.Next;
  LIterator.Recurse; // enter array object

LIterator.Key +': '+ LIterator.AsString

  LIterator.Return; // back to parent structure

c++builder的迭代器

https://community.embarcadero.com/blogs/entry/how-to-get-the-array-using-the-tjsoniterator-delphi-japan

It is a new function of 10.2.2, and it can be outputted by Ext JS store definition.

https://community.embarcadero.com/blogs/entry/it-is-a-new-function-of-10-2-2-and-it-can-be-outputted-by-ext-js-store-definition

function TServerMethods1.GetDepartmentNames: TFDJSONDataSets;
begin
  // Clear active so that query will reexecute
  FDQueryDepartmentNames.Active := False;

  Result := TFDJSONDataSets.Create;
  TFDJSONDataSetsWriter.ListAdd(Result, FDQueryDepartmentNames);
end;

function TServerMethods1.GetDepartmentNamesJSON: TJSONObject;
var
  LDataSets: TFDJSONDataSets;
begin
  LDataSets := GetDepartmentNames;
  try
    Result := TJSONObject.Create;
    TFDJSONInterceptor.DataSetsToJSONObject(LDataSets, Result);
  finally
    LDataSets.Free;
  end;
end;

function TServerMethods1.GetDepartmentNames: TFDJSONDataSets;
begin
  // Clear active so that query will reexecute
  FDQueryDepartmentNames.Active := False;

  Result := TFDJSONDataSets.Create;
  TFDJSONDataSetsWriter.ListAdd(Result, FDQueryDepartmentNames);
end;

procedure TDepartmentsClientForm.UpdateDepartmentNames(const ADataSetList: TFDJSONDataSets);
begin
  // Update UI
  FDMemTableDepartments.Active  := False;
  Assert(TFDJSONDataSetsReader.GetListCount(ADataSetList) = );
  FDMemTableDepartments.AppendData(
    TFDJSONDataSetsReader.GetListValue(ADataSetList, ));
end;

Tokyo 10.2.2

TFDBatchMoveJSONWriter

https://community.embarcadero.com/blogs/entry/dataset-mapping-to-json-for-javascript-client-support-in-rad-studio-10-2-2

dataset2json

FDBatchMove1
FDBatchMoveJSONWriter1
FDBatchMoveDataSetReader1.dataset=qryPerson;
self.FDBatchMove1.Reader := self.FDBatchMoveDataSetReader1;
self.FDBatchMove1.Writer := self.FDBatchMoveJSONWriter1;

然后就得到dataset转换后的json string了.

procedure TForm3.Button3Click(Sender: TObject);
var
  sstr: TStringStream;
begin
  sstr := TStringStream.Create('',TEncoding.UTF8);
  try
    FDBatchMoveJSONWriter1.Stream := sstr;
    FDBatchMove1.Execute;
    Memo1.Lines.Text :=sstr.DataString;
  finally
    sstr.Free;
  end;
end;

TJsonSerializer

序列化，反序列化

json2DataSet

http://blog.csdn.net/bzt820801/article/details/77984967

第三方优秀的库

JsonDataObjects

https://github.com/ahausladen/JsonDataObjects

XSuperObject

https://github.com/onryldz/x-superobject

数组反序列化

  userList: TArray<TUser>;
  user: TUser;
begin
  userList := XSuperObject.TJSON.Parse < TArray < TUser >> (Memo1.Text);

在x-superobject和TJsonSerializer在Android下都报错。2018.1.25 Tokyo 10.2.2 error。期待下一版本。

官方的例子，好好学习吧

https://community.embarcadero.com/blogs/entry/dataset-mapping-to-json-for-javascript-client-support-in-rad-studio-10-2-2

http://blog.marcocantu.com/blog/2017-december-dataset-mapping-json.html

datasetToJSON

procedure TForm5.Button1Click(Sender: TObject);
var
  sstr: TStringStream;
begin
  sstr := TStringStream.Create;
  try
    EmployeeTable.Active := True;
    FDBatchMoveJSONWriter1.Stream := sstr;
    FDBatchMove1.Execute;
    ShowMessage(sstr.DataString);
  finally
    sstr.Free;
  end;
end;

procedure TEmployeeResource1.Get(const AContext: TEndpointContext; const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
var
  mStream: TMemoryStream;
begin
  mStream := TMemoryStream.Create;
  AResponse.Body.SetStream(mStream, 'application/json', True);
  FDBatchMoveJSONWriter1.Stream := mStream;
  FDBatchMove1.Execute;
end;

procedure TEmployeeResource1.Get(const AContext: TEndpointContext; const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
begin
  FDBatchMoveJSONWriter1.JsonWriter := AResponse.Body.JsonWriter;
  FDBatchMove1.Execute;
end;

https://community.embarcadero.com/blogs/entry/dataset-json-javascript

https://community.embarcadero.com/blogs/entry/c-builder-10-2-2-dataset-mapping-to-json-for-javascript-client-support

procedure TGroupsResource1.Get(const AContext: TEndpointContext;
  const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
var
  ms: TMemoryStream;
begin
  ms := TMemoryStream.Create;
  EmployeeTable.Close;
  try
    EmployeeTable.Open;
    EmployeeTable.SaveToStream(ms, TFDStorageFormat.sfJSON);
    AResponse.Body.SetStream(ms, 'application/json', True);
  finally
    ms.Free;
  end;
end;

最新封装delphi DataSetToJSON单元函数 Tokyo 10.2.2

{*******************************************************}
{                                                       }
{       DataSet2JSON                                    }
{                                                       }
{       Copyright (C) 2018 KT                         }
{                                                       }
{*******************************************************}

unit ktDS2JSON;

interface

uses Data.DB, System.Classes, FireDAC.Comp.BatchMove, FireDAC.Comp.Client, FireDAC.Comp.BatchMove.DataSet, FireDAC.Comp.BatchMove.JSON,
  System.SysUtils, FireDAC.Comp.DataSet;

function ds2JSON(ads: TDataSet): string;

implementation

function ds2JSON(ads: TDataSet): string;
var
  ssm: TStringStream;
  table: TFDMemTable;
  FDBatchMove: TFDBatchMove;
  FDBatchMoveDataSetReader: TFDBatchMoveDataSetReader;
  FDBatchMoveJSONWriter: TFDBatchMoveJSONWriter;

begin
  ssm := TStringStream.Create('', TEncoding.UTF8);
  table := TFDMemTable.Create(nil);
  FDBatchMove := TFDBatchMove.Create(nil);

  table.CopyDataSet(ads, [coRestart, coAppend, coStructure]);

  FDBatchMoveDataSetReader := TFDBatchMoveDataSetReader.Create(nil);
  FDBatchMoveDataSetReader.DataSet := ads;
  FDBatchMoveJSONWriter := TFDBatchMoveJSONWriter.Create(nil);
  FDBatchMoveJSONWriter.Stream := ssm;
  FDBatchMove.Reader := FDBatchMoveDataSetReader;
  FDBatchMove.Writer := FDBatchMoveJSONWriter;
  FDBatchMove.Execute;

  Result := ssm.DataString;

  ssm.Free;
  table.Free;
  FDBatchMove.Free;
  FDBatchMoveDataSetReader.Free;
  FDBatchMoveJSONWriter.Free;

end;

end.

NULL值判断，空置判断 存在判断

  if( (jo.GetValue('data').Null )  ) then
  begin
    self.errmsg := '没有数据';
    MsgWarning(errmsg);
    exit;
  end;

https://community.idera.com/developer-tools/b/blog/posts/returning-json-tjsonvalue-tjsonwriter-and-other-options-from-rad-server