---
url: >-
  /statelake/scripting-reference/json-for-scripts/modifying-child-elements-of-json-objects-and-arrays.md
---

# Modifying Child Elements Of JSON Objects And Arrays

## Adding Or Updating Children Of TJSONObject

To add or update a child of a JSON object you can use the square brackets operator:

Object\[‘key’] := SomeJSONValue;

Make sure the passed value is a **TJSONValue**. For example, if you want to put a string field into a JSON object, you need to create a **TJSONString** object and upcast it to **TJSONValue**:

Object\[‘key’] := TJSONString.Create(‘Hello World’) **as** TJSONValue;

**Remember**: Once you enclosed one **TJSONValue** into another, the enclosed object will belong to its new owner, which means that **Free** method of the owner will take care of releasing the enclosed **TJSONValue** object memory.

If the value already exists by the specified key, it’s recommended to remove it and release its memory first. (see “**Removing Children From TJSONObject**”)

You can enclose JSON objects into each other following the same approach:

```pascal
var
    ParentObject, ChildObject: TJSONObject;
begin
    ParentObject := TJSONObject.Create;
    ChildObject := TJSONObject.Create;
    ParentObject[‘subobject’] := ChildObject;
    ParentObject.Free;
end;
```

## Removing Children From TJSONObject

To remove a child from **TJSONObject** you can use **TJSONObject.Remove** method:

Object.Remove(‘key’);

**Remember**: This method does not release the memory of the removed entity, it only removes a child from a list of children. You can either move the reference to the removed entity into another variable:

```pascal
var
    RemovedValue: TJSONValue;
…
RemovedValue := Object.Remove(‘key’);
```

or release its memory straight away as follows:

Object.Remove(‘key’).Free;

**Remember**: If you ignore the result of **Remove** method, you will cause a memory leak.

## Adding Children To TJSONArray

To add an element to a **TJSONArray** object you may use the **Add** method:

Array.Add(Value);

The passed value must be a **TJSONValue**. For example, if you want to put a string value into a JSON array, you need to create a **TJSONString** object and upcast it to **TJSONValue**:

Array.Add(TJSONString.Create(‘Hello World’) **as** TJSONValue);

```pascal
var
    Arr: TJSONArray;
begin
    Arr := TJSONArray.Create;
    Arr.Add(TJSONNumber.Create(100) as TJSONValue);
    Arr.Add(TJSONNumber.Create(200) as TJSONValue);
    …
    Arr.Free;
end;
```

## Removing Children From TJSONArray

To remove an item from a JSON array, you may use the **Remove** method:

Array.Remove(0);

However, this method does not release the memory of the removed entity, it only removes a child from a list of children. You can either move the reference to the removed entity into another variable:

```pascal
var
   RemovedValue: TJSONValue;
   …
RemovedValue := Array.Remove(0);
```

or release its memory straight away as follows:

Array.Remove(0).Free;

**Remember**: If you ignore the result of **Remove** method, you will cause a memory leak.