README

# Delphi-JsonToDelphiClass

This is a fork of Petar Georgiev with improvements of Jens Borrisholt and Marlon Nardi

JsonToDelphi Online

https://jsontodelphi.com

Fixes & Features: 20th May 2026

Features

• Modernized the online generator main screen with a new HTMLFrame-based interface.
• Added a larger JSON editor experience with direct actions for:
  • Generate Unit
  • Validate JSON
  • Sample Use
  • Pretty print
  • Clear JSON
• Improved generation options layout for PascalCase, JsonProperty attributes, zero-date suppression and class-name postfixing.
• Added a top PayPal donation button and kept project support links available in the support area.
• Improved SEO and AI discovery metadata:
  • Canonical URL
  • Open Graph tags
  • Twitter Card tags
  • Schema.org JSON-LD for WebSite and WebApplication
  • Richer keywords and application descriptions for JSON to Delphi, JSON to Pascal and Delphi DTO generation
• Corrected robots.txt sitemap URL and enriched sitemap.xml.

Build / publishing

• The uniGUI web application is published as an ISAPI DLL on IIS.
• Publication builds should keep UNIGUI_DLL enabled in unigui\JsonToDelphi.dpr.
• Latest DLL build produced during this update: 2.1.0.204.

Fixes & Features: 7th December 2025

Features

• Added full support for 2D arrays of simple JSON types (TArray<TArray<string>>).
• New internal logic to detect array dimensions during JSON parsing.
• Arrays up to 2 levels deep are now supported when containing only simple types (string, number, boolean).
• Automatic generation of TList<TArray<string>> wrapper properties compatible with Pkg.Json.DTO.

Fixes

• Issue #9 resolved – nested arrays no longer produce:
  "TPkgJsonMapper.GenerateUnit: Nested arrays are not supported!"
• Fixed memory leaks related to:
  • TPkgJsonMapper
  • TStubClass
  • TStubFieldList
  • TStubFieldObjectList
  • TStubArrayField
• Corrected destructor logic for stub lifecycle cleanup.
• Improved parser behavior to avoid invalid propagation of jtArray.
• Added validation to block unsupported cases:
  • Arrays of arrays containing objects
  • Arrays with more than two dimensions

Example

JSON Input

{
  "values":[
    ["a", "b"],
    ["c", "d"]
  ]
}

Before

❌ Nested arrays generated an exception:
Nested arrays are not supported!

After

✅ Full support for arrays like:

[ ["a","b"], ["c","d"] ]

Fixes & Features: 16th June 2024

Features

• JSON null property are now mapped to a string.

Eg this JSON

[
    {
        "createdAt": null,
        "updatedAt": "2013-05-28T15:47:57.962Z",
        "username": "jacquelyn88"
    }
]

Generates the following DTO:

  TItems = class
  private
    FCreatedAt: string;
    [SuppressZero]
    FUpdatedAt: TDateTime;
    FUsername: string;
  published
    property CreatedAt: string read FCreatedAt write FCreatedAt;
    property UpdatedAt: TDateTime read FUpdatedAt write FUpdatedAt;
    property Username: string read FUsername write FUsername;
  end;

Fixes & Features: 19th January 2024

Features

• Upgrade to Delphi 12
• Added Clone function on TJsonDTO class

Bugs:

• Unittest TestDateTime didnt pass under Delphi 12
• Added missing Reserved words

Fixes & Features: 06th February 2022

Features

• More interceptors where published in a new repo: https://github.com/JensBorrisholt/Json-Interceptors
• Added the possibility to download Pkg.Json.DTO.pas from https://jsontodelphi.com/

Fixes & Features: 26h December 2021

Features

• Added new class generation options

Bugs:

• Fixed rename unit on generation screen
• Fixed screen alignment

Fixes & Features: 03h October 2021

Bugs:

• Wrong type detection. '2019-08-29' wasn't recognized as a Date, but a string
• All unittests didn't pass
• In the generator main form, the correct JSON wans't allways read from the MEMO
• In the generator main form, the JSON wasn't allways updated

Features

• Upgraded to Delphi 11
• New property attribute : [SuppressZero] Delphi doesn't support Nullable types, so use this attribute to strip TDateTime property where value is 0.

A Small example:

type
  TDateTimeDTO = class(TJsonDTO)
  private
    [SuppressZero]
    FSuppressDate: TDateTime;
    FNoSuppressDate: TDateTime;
  public
    property DateSuppress: TDateTime read FSuppressDate write FSuppressDate;
    property NoDateSuppress: TDateTime read FNoSuppressDate write FNoSuppressDate;
  end;

The above class will generate the following JSON, if both properties is 0

{
  "suppressDate": "",
  "noSuppressDate": "1899-12-30T00:00:00.000Z"
}

NOTE: You can turn off this feature in the settings form

Fixes & Features: 04th June 2021

Bugs:

• An error message occured when switching between the diffrent demo files
• Dates without timestamp wasn't recognized within the RegEx
• Compile error in unit tests
• Updated elements in a list wasn't applied to the generated json.
• Issue #2 Out of memory error and High CPU usage - Thank You MarkRSill

Features

• Added unit tests for updating elements in lists.

Fixes & Features: 26th Marts 2021

Bugs:

• The same class name could appear multiple times:

E.g this JSON generated faulty code:

{
  "/": {
    "readonly": true
  },
  "\\": {
    "readonly": true
  }
}

Fixes & Features: 22th December 2020

Bugs:

Features

• New main form. Completly rewritten.
• Support for BSON
• Support for Minify JSON
• Support for multiblt output formats
• JSON are now minifyed before posted to the validator. Means support for larger JSONs to be validated.
• Version 3.0 released.

Fixes & Features: 11th December 2020

Bugs:

• "id": "01010101" faulty generated a TDateTime property not string.
• Settings.AddJsonPropertyAttributes didn't generate a Property Attribute

Features

• JSON are now posted directly to the validator
• Better property name generator
• More unit tests

Fixes & Features: 24th November 2020

Bugs:

Features

• Possibility to change the postfix of ClassNames, via Settings Dialog. Default: DTO
• Settings Dialog rewritten to use LiveBindings
• Create a Demo Project, using your Json Data

Fixes & Features: 22th November 2020

Bugs:

• Demo generator didn't allways generate valid code
• Stopped the generator from generating surplus classes.

Features

• Non object arrays are now mapped into a TList<T> instead of TArray<T>
• Added a settings dialog and settings class
• Properties in PascalCase (Setting)
• Allways use JsonName property annotation (Setting)
• Support for objects with diffrents properties in an Array

Eg this JSON

{
  "ArrayTest": [
    {
      "S1": "5102"
    },
    {
      "S2": "True"
    }
  ]
}

Generates the following DTO:

  TArrayTestDTO = class
  private
    FS1: string;
    FS2: string;
  published
    property S1: string read FS1 write FS1;
    property S2: string read FS2 write FS2;
  end;

Previous changes

• Only floating point numbers are mapped to Double
• Numbers are mapped to Integer or Int64 depending on their size
• Generated code restructored, and simplified
• Generated classes inheriteds from TJsonDTO
• Socurce Code restructored
• Parser logic seperated from GUI logic
• Fixed bug in the RegEx for recognizing an ISO8601 Date
• Serialization removed the "noise" of List<T> i.e. includes internal properties that did not exist in the original JSON string.
• Generated code uses TObjectList<T>

Generates Delphi Classes based on JSON string. Just like XML Data Binding, but for JSON.

Main features

• Build entirely on the RTL (no external dependencies) so it's cross-platform;
• Accepts any valid JSON string, no matter how complex the object is;
• Visualizes the structure of the JSON objects in a treeview;
• Generates complete delphi unit (declaration and implementation), based on the JSON string input;
• Automatically prefixes reserved Delphi words with "&" (ampersand);
• Support for JSON string that contains empty Array;
• Adds support code to automatically destroy complex sub types. So you don't have to manage subobject's lifetime manually;
• Uses TObjectList<T> to represent lists;
• Adds helper serialization/deserialization functions;
• Serialization and deserialization results in the same JSON structure!
• Automatically detects date/datetime parts and maps them to TDate/TDateTime (as long as dates are ISO8601 compliant);
• Maps floating point numbers to Double
• Maps Number to Integer or Int64 depending on the number
• Maps true/false values to Boolean;
• Supports JSON pretty print to format the input string;
• Simple and responsive GUI;
• Automatic check for update, based on ITask (Parallel Programming Library)!
• It's open source! You can find the source code and binary releases on GitHub.

• If the JSON array is empty the contained type is unknown. Unit generation works only with known and supported types.

*** The releases of JsonToDelphiClass (source and binaries) are public and reside on GitHub. The update unit uses GitHub's REST API to enumerate tags/releases.

Report any problems/suggestions using GitHub's facilities.