I have a JSON like this:

{
"Content": [{
    "Identifier": "AABBCC",
    "Description": "test terfdfg",
    "GenericProductIdentifier": "AABBCC",
    "ProductFamilyDescription": "sampling",
    "LifeCycleStatus": "ACTIVE",
    "Price": {
        "Value": 1.00,
        "Quantity": 1000
    },
    "LeadTimeWeeks": "16",
    "FullBoxQty": 200,
}],
"TotalElements": 1,
"TotalPages": 1,
"NumberOfElements": 1,
"First": true,
"Size": 1,
"Number": 0
}

In Delphi 10.4, I'm trying to parse it, but I can't access the values ​​contained in 'Price'.

I wrote code like this:

var
  vContent: TJSONArray;
  vJson: TJSONObject;
  vContentRow: TJSONObject;
  i,j : Integer;
begin
  Memo2.Lines.Clear;

  if Memo1.Text = '' then
    exit;

  vJson := TJSONObject(TJSONObject.ParseJSONValue(TEncoding.ASCII.GetBytes(Memo1.Text),0));
  try
    vContent := TJSONArray(vJson.Get('Content').JsonValue);

    for i := 0 to Pred(vContent.Count) do
    begin
      vContentRow := TJSONObject(vContent.Items[i]);
      for j := 0 to Pred(vContentRow.Count) do
      begin
        Memo2.Lines.Add('  '  vContentRow.Get(j).JsonString.Value ' : '  vContentRow.Get(j).JsonValue.Value);
      end;
    end;

    Memo2.Lines.Add(vContent.Value);
  finally

  end;
end;

What is the correct way to read the values ​​contained in 'Price'?

CodePudding user response：

Here is a sample code to parse your JSON:

uses
  System.IOUtils, System.JSON, System.Generics.Collections;

procedure TForm1.Button1Click(Sender: TObject);

  procedure GetPrices(const S: string);
  var
    V: TJsonValue;
    O, E, P: TJsonObject;
    A: TJsonArray;
  begin
    V := TJSONObject.ParseJSONValue(S);
    if not Assigned(V) then
      raise Exception.Create('Invalid JSON');
    try
      O := V as TJSONObject;
      A := O.GetValue<TJsonArray>('Content');
      for var I := 0 to A.Count - 1 do
      begin
        E := A.Items[I] as TJsonObject; // Element
        P := E.GetValue<TJsonObject>('Price');
        ShowMessage('Value: '   P.GetValue<string>('Value')   '  '   'Quantity: '    P.GetValue<string>('Quantity'));
      end;
    finally
      V.Free;
    end;
  end;

var
  S: string;
begin
  S := TFile.ReadAllText('d:\json.txt'); // Retrieve it using some webservice
  GetPrices(S);
end;

Note, your JSON is invalid, the corect definition is:

{
    "Content": [{
        "Identifier": "AABBCC",
        "Description": "test terfdfg",
        "GenericProductIdentifier": "AABBCC",
        "ProductFamilyDescription": "sampling",
        "LifeCycleStatus": "ACTIVE",
        "Price": {
            "Value": 1.00,
            "Quantity": 1000
        },
        "LeadTimeWeeks": "16",
        "FullBoxQty": 200
    }],
    "TotalElements": 1,
    "TotalPages": 1,
    "NumberOfElements": 1,
    "First": true,
    "Size": 1,
    "Number": 0
}

CodePudding user response：

You can use the JSON library of Delphi. The JSON library has the JsonToObject class function that can convert directly the string to an Object (Object structure)

See this: https://docwiki.embarcadero.com/Libraries/Sydney/en/REST.Json.TJson.JsonToObject

You can create the classes structure manually o using the web: https://jsontodelphi.com/

The classes structure for your JSON created is this:

type
  TPrice = class;

  TPrice = class
  private
    FQuantity: Integer;
    FValue: Double;
  published
    property Quantity: Integer read FQuantity write FQuantity;
    property Value: Double read FValue write FValue;
  end;
  
  TContent = class
  private
    FDescription: string;
    FFullBoxQty: Integer;
    FGenericProductIdentifier: string;
    FIdentifier: string;
    FLeadTimeWeeks: string;
    FLifeCycleStatus: string;
    FPrice: TPrice;
    FProductFamilyDescription: string;
  published
    property Description: string read FDescription write FDescription;
    property FullBoxQty: Integer read FFullBoxQty write FFullBoxQty;
    property GenericProductIdentifier: string read FGenericProductIdentifier write FGenericProductIdentifier;
    property Identifier: string read FIdentifier write FIdentifier;
    property LeadTimeWeeks: string read FLeadTimeWeeks write FLeadTimeWeeks;
    property LifeCycleStatus: string read FLifeCycleStatus write FLifeCycleStatus;
    property Price: TPrice read FPrice;
    property ProductFamilyDescription: string read FProductFamilyDescription write FProductFamilyDescription;
  public
    constructor Create;
    destructor Destroy; override;
  end;
  
  TRoot = class(TJsonDTO)
  private
    [JSONName('Content'), JSONMarshalled(False)]
    FContentArray: TArray<TContent>;
    [GenericListReflect]
    FContent: TObjectList<TContent>;
    FFirst: Boolean;
    FNumber: Integer;
    FNumberOfElements: Integer;
    FSize: Integer;
    FTotalElements: Integer;
    FTotalPages: Integer;
    function GetContent: TObjectList<TContent>;
  protected
    function GetAsJson: string; override;
  published
    property Content: TObjectList<TContent> read GetContent;
    property First: Boolean read FFirst write FFirst;
    property Number: Integer read FNumber write FNumber;
    property NumberOfElements: Integer read FNumberOfElements write FNumberOfElements;
    property Size: Integer read FSize write FSize;
    property TotalElements: Integer read FTotalElements write FTotalElements;
    property TotalPages: Integer read FTotalPages write FTotalPages;
  public
    destructor Destroy; override;
  end;

Now, the code for parse elements is more simple. You only need a code like this to access different properties of your structure:

var
  Root: TRoot;
begin
  root := TJSON.JsonToObject<TRoot>(Memo1.Lines.Text);
  lblid.Caption := 'TotalElements: '   Root.TotalElements.ToString;
  lblvalue.Caption := 'TotalPages: '   Root.TotalPages.ToString;
  lblcount.Caption := 'Identifier: '   Root.Content[0].Identifier;
  lblfirstonclick.Caption := 'Description: '   Root.Content[0].Description;
  lbllastonclick.Caption := 'Price/Quantity:'   Root.Content[0].Price.Quantity.ToString;
  //...