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# `Fn::ToJsonString`
<a name="intrinsic-function-reference-ToJsonString"></a>

The `Fn::ToJsonString` intrinsic function converts an object or array to its corresponding JSON string.

**Important**  
You must use the [`AWS::LanguageExtensions` transform](transform-aws-languageextensions.md) to use the `Fn::ToJsonString` intrinsic function.

## Declaration
<a name="tojsonstring-declaration"></a>

### JSON
<a name="intrinsic-function-reference-tojsonstring-syntax.json"></a>

```
{ "Fn::ToJsonString": Object }
```

```
{ "Fn::ToJsonString": Array }
```

### YAML
<a name="intrinsic-function-reference-tojsonstring-syntax.yaml"></a>

```
Fn::ToJsonString: Object
```

```
Fn::ToJsonString: Array
```

## Parameters
<a name="tojsonstring-parameters"></a>

`Object`  
The object you want to convert to a JSON string.

`Array`  
The array you want to convert to a JSON string.

## Return value
<a name="intrinsic-function-reference-tojsonstring-return"></a>

The object or array converted to a JSON string. 

## Examples
<a name="intrinsic-function-reference-tojsonstring-examples"></a>

### Convert an object to a JSON string
<a name="intrinsic-function-reference-tojsonstring-example-subsection"></a>

This example snippet converts the object passed to the intrinsic function to a JSON string.

#### JSON
<a name="intrinsic-function-reference-tojsonstring-example.json"></a>

```
{
//...
    "Transform": "AWS::LanguageExtensions"
    //...
        "Fn::ToJsonString": {
            "key1": "value1",
            "key2": { 
                "Ref": "ParameterName"
            }
        }
//...
}
```

#### YAML
<a name="intrinsic-function-reference-tojsonstring-example.yaml"></a>

```
Transform: 'AWS::LanguageExtensions'
#...
  Fn::ToJsonString: 
    key1: value1
    key2: !Ref ParameterName
#...
```

In both of these examples, if the `Ref` to `ParameterName` resolves to `resolvedValue`, the function resolves to the following JSON string:

```
"{\"key1\":\"value1\",\"key2\":\"resolvedValue\"}"
```

### Convert an array to a JSON string
<a name="intrinsic-function-reference-tojsonstring-example2"></a>

This example snippet converts the array passed to the intrinsic function to a JSON string.

#### JSON
<a name="intrinsic-function-reference-tojsonstring-example2.json"></a>

```
{
//...
    "Transform": "AWS::LanguageExtensions"
    //...
        "Fn::ToJsonString": [{
            "key1": "value1",
            "key2": { 
                "Ref": "ParameterName" 
            }
        }]
//...
}
```

#### YAML
<a name="intrinsic-function-reference-tojsonstring-example2.yaml"></a>

```
Transform: 'AWS::LanguageExtensions'
#...
  Fn::ToJsonString: 
    - key1: value1
      key2: !Ref ParameterName
#...
```

In both of these examples, if the `Ref` to `ParameterName` resolves to `resolvedValue`, the function resolves to the following JSON String:

```
"[{\"key1\":\"value1\"},{\"key2\":\"resolvedValue\"}]"
```

## Supported functions
<a name="tojsonstring-supported-functions"></a>

You can use the following functions in the `Fn::ToJsonString` intrinsic function or array:
+ `Fn::Base64`
+ `Fn::FindInMap`
+ `Fn::GetAtt`
+ `Fn::GetAZs`
+ `Fn::If`
+ `Fn::ImportValue`
+ `Fn::Join`
+ `Fn::Length`
+ `Fn::Select`
+ `Fn::Split`
+ `Fn::Sub`
+ `Fn::ToJsonString`
+ `Ref`