FJsonObjectConverter Class Reference

#include <JsonObjectConverter.h>

Public Types
using	CustomExportCallback = TDelegate< TSharedPtr< FJsonValue >(FProperty *Property, const void *Value)>
using	CustomImportCallback = TDelegate< bool(const TSharedPtr< FJsonValue > &JsonValue, FProperty *Property, void *Value)>

Static Public Member Functions
static JSONUTILITIES_API FString	StandardizeCase (const FString &StringIn)
static JSONUTILITIES_API bool	GetTextFromObject (const TSharedRef< FJsonObject > &Obj, FText &TextOut)
static JSONUTILITIES_API bool	GetTextFromField (const FString &FieldName, const TSharedPtr< FJsonValue > &FieldValue, FText &TextOut)
template<typename InStructType >
static TSharedPtr< FJsonObject >	UStructToJsonObject (const InStructType &InStruct, int64 CheckFlags=0, int64 SkipFlags=0, const CustomExportCallback *ExportCb=nullptr)
static JSONUTILITIES_API bool	UStructToJsonObject (const UStruct *StructDefinition, const void *Struct, TSharedRef< FJsonObject > OutJsonObject, int64 CheckFlags=0, int64 SkipFlags=0, const CustomExportCallback *ExportCb=nullptr, EJsonObjectConversionFlags ConversionFlags=EJsonObjectConversionFlags::None)
static JSONUTILITIES_API bool	UStructToJsonObjectString (const UStruct *StructDefinition, const void *Struct, FString &OutJsonString, int64 CheckFlags=0, int64 SkipFlags=0, int32 Indent=0, const CustomExportCallback *ExportCb=nullptr, bool bPrettyPrint=true)
template<typename InStructType >
static bool	UStructToJsonObjectString (const InStructType &InStruct, FString &OutJsonString, int64 CheckFlags=0, int64 SkipFlags=0, int32 Indent=0, const CustomExportCallback *ExportCb=nullptr, bool bPrettyPrint=true)
template<typename CharType , template< typename > class PrintPolicy>
static bool	UStructToFormattedJsonObjectString (const UStruct *StructDefinition, const void *Struct, FString &OutJsonString, int64 CheckFlags=0, int64 SkipFlags=0, int32 Indent=0, const CustomExportCallback *ExportCb=nullptr, EJsonObjectConversionFlags ConversionFlags=EJsonObjectConversionFlags::None)
static JSONUTILITIES_API bool	UStructToJsonAttributes (const UStruct *StructDefinition, const void *Struct, TMap< FString, TSharedPtr< FJsonValue > > &OutJsonAttributes, int64 CheckFlags=0, int64 SkipFlags=0, const CustomExportCallback *ExportCb=nullptr, EJsonObjectConversionFlags ConversionFlags=EJsonObjectConversionFlags::None)
static JSONUTILITIES_API TSharedPtr< FJsonValue >	UPropertyToJsonValue (FProperty *Property, const void *Value, int64 CheckFlags=0, int64 SkipFlags=0, const CustomExportCallback *ExportCb=nullptr, FProperty *OuterProperty=nullptr, EJsonObjectConversionFlags ConversionFlags=EJsonObjectConversionFlags::None)
static JSONUTILITIES_API bool	JsonObjectToUStruct (const TSharedRef< FJsonObject > &JsonObject, const UStruct *StructDefinition, void *OutStruct, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
template<typename OutStructType >
static bool	JsonObjectToUStruct (const TSharedRef< FJsonObject > &JsonObject, OutStructType *OutStruct, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
static JSONUTILITIES_API bool	JsonAttributesToUStruct (const TMap< FString, TSharedPtr< FJsonValue > > &JsonAttributes, const UStruct *StructDefinition, void *OutStruct, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
static JSONUTILITIES_API bool	JsonValueToUProperty (const TSharedPtr< FJsonValue > &JsonValue, FProperty *Property, void *OutValue, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
template<typename OutStructType >
static bool	JsonObjectStringToUStruct (const FString &JsonString, OutStructType *OutStruct, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
template<typename OutStructType >
static bool	JsonArrayStringToUStruct (const FString &JsonString, TArray< OutStructType > *OutStructArray, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
template<typename OutStructType >
static bool	JsonArrayToUStruct (const TArray< TSharedPtr< FJsonValue > > &JsonArray, TArray< OutStructType > *OutStructArray, int64 CheckFlags=0, int64 SkipFlags=0, const bool bStrictMode=false, FText *OutFailReason=nullptr, const CustomImportCallback *ImportCb=nullptr)
static JSONUTILITIES_API FFormatNamedArguments	ParseTextArgumentsFromJson (const TSharedPtr< const FJsonObject > &JsonObject)

Static Public Attributes
static JSONUTILITIES_API const CustomExportCallback	ExportCallback_WriteISO8601Dates

Detailed Description

Class that handles converting Json objects to and from UStructs

Member Typedef Documentation

CustomExportCallback

using FJsonObjectConverter::CustomExportCallback = TDelegate<TSharedPtr<FJsonValue>(FProperty* Property, const void* Value)>

Optional callback that will be run when exporting a single property to Json. If this returns a valid value it will be inserted into the export chain. If this returns nullptr or is not bound, it will try generic type-specific export behavior before falling back to outputting ExportText as a string.

CustomImportCallback

using FJsonObjectConverter::CustomImportCallback = TDelegate<bool(const TSharedPtr<FJsonValue>& JsonValue, FProperty* Property, void* Value)>

Optional callback that will be run when importing a single property from Json. If this returns true, it should have successfully turned the Json value into the property value. If this returns false or is not bound, it will try generic type-specific import behavior before failing.

Member Function Documentation

GetTextFromField()

bool FJsonObjectConverter::GetTextFromField ( const FString &  FieldName, const TSharedPtr< FJsonValue > &  FieldValue, FText &  TextOut  )

static

Convert a Json value to text (takes some hints from the value name)

GetTextFromObject()

bool FJsonObjectConverter::GetTextFromObject ( const TSharedRef< FJsonObject > &  Obj, FText &  TextOut  )

static

Parse an FText from a json object (assumed to be of the form where keys are culture codes and values are strings)

JsonArrayStringToUStruct()

template<typename OutStructType >

static bool FJsonObjectConverter::JsonArrayStringToUStruct ( const FString &  JsonString, TArray< OutStructType > *  OutStructArray, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

inlinestatic

Converts from a json string containing an array to an array of UStructs

Parameters

JsonString	String containing JSON formatted data.
OutStructArray	The UStruct array to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags.
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any properties matched but failed to deserialize.

JsonArrayToUStruct()

template<typename OutStructType >

static bool FJsonObjectConverter::JsonArrayToUStruct ( const TArray< TSharedPtr< FJsonValue > > &  JsonArray, TArray< OutStructType > *  OutStructArray, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

inlinestatic

Converts from an array of json values to an array of UStructs.

Parameters

JsonArray	Array containing json values to convert.
OutStructArray	The UStruct array to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags.
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any of the matching elements are not an object, or if one of the matching elements could not be converted to the specified UStruct type.

JsonAttributesToUStruct()

bool FJsonObjectConverter::JsonAttributesToUStruct ( const TMap< FString, TSharedPtr< FJsonValue > > &  JsonAttributes, const UStruct *  StructDefinition, void *  OutStruct, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

static

Converts a set of json attributes (possibly from within a JsonObject) to a UStruct, using importText

Parameters

JsonAttributes	Json Object to copy data out of
StructDefinition	UStruct definition that is looked over for properties
OutStruct	The UStruct instance to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any properties matched but failed to deserialize

JsonObjectStringToUStruct()

template<typename OutStructType >

static bool FJsonObjectConverter::JsonObjectStringToUStruct ( const FString &  JsonString, OutStructType *  OutStruct, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

inlinestatic

Converts from a json string containing an object to a UStruct

Parameters

JsonString	String containing JSON formatted data.
OutStruct	The UStruct instance to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any properties matched but failed to deserialize

JsonObjectToUStruct() [1/2]

bool FJsonObjectConverter::JsonObjectToUStruct ( const TSharedRef< FJsonObject > &  JsonObject, const UStruct *  StructDefinition, void *  OutStruct, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

static

Converts from a Json Object to a UStruct, using importText

Parameters

JsonObject	Json Object to copy data out of
StructDefinition	UStruct definition that is looked over for properties
OutStruct	The UStruct instance to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any properties matched but failed to deserialize

JsonObjectToUStruct() [2/2]

template<typename OutStructType >

static bool FJsonObjectConverter::JsonObjectToUStruct ( const TSharedRef< FJsonObject > &  JsonObject, OutStructType *  OutStruct, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

inlinestatic

Templated version of JsonObjectToUStruct

Parameters

JsonObject	Json Object to copy data out of
OutStruct	The UStruct instance to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if any properties matched but failed to deserialize

JsonValueToUProperty()

bool FJsonObjectConverter::JsonValueToUProperty ( const TSharedPtr< FJsonValue > &  JsonValue, FProperty *  Property, void *  OutValue, int64  CheckFlags = 0, int64  SkipFlags = 0, const bool  bStrictMode = false, FText *  OutFailReason = nullptr, const CustomImportCallback *  ImportCb = nullptr  )

static

Converts a single JsonValue to the corresponding FProperty (this may recurse if the property is a UStruct for instance).

Parameters

JsonValue	The value to assign to this property
Property	The FProperty definition of the property we're setting.
OutValue	Pointer to the property instance to be modified.
CheckFlags	Only convert sub-properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip sub-properties that match any of these flags
bStrictMode	Whether to strictly check the json attributes
OutFailReason	Reason of the failure if any
ImportCb	Optional callback to override import behaviour, if this returns false it will fallback to the default

Returns

False if the property failed to serialize

ParseTextArgumentsFromJson()

FFormatNamedArguments FJsonObjectConverter::ParseTextArgumentsFromJson ( const TSharedPtr< const FJsonObject > &  JsonObject )

static

StandardizeCase()

FString FJsonObjectConverter::StandardizeCase ( const FString &  StringIn )

static

FName case insensitivity can make the casing of UPROPERTIES unpredictable. Attempt to standardize output.

UPropertyToJsonValue()

TSharedPtr< FJsonValue > FJsonObjectConverter::UPropertyToJsonValue ( FProperty *  Property, const void *  Value, int64  CheckFlags = 0, int64  SkipFlags = 0, const CustomExportCallback *  ExportCb = nullptr, FProperty *  OuterProperty = nullptr, EJsonObjectConversionFlags  ConversionFlags = EJsonObjectConversionFlags::None  )

static

UStructToFormattedJsonObjectString()

template<typename CharType , template< typename > class PrintPolicy>

static bool FJsonObjectConverter::UStructToFormattedJsonObjectString ( const UStruct *  StructDefinition, const void *  Struct, FString &  OutJsonString, int64  CheckFlags = 0, int64  SkipFlags = 0, int32  Indent = 0, const CustomExportCallback *  ExportCb = nullptr, EJsonObjectConversionFlags  ConversionFlags = EJsonObjectConversionFlags::None  )

inlinestatic

Wrapper to UStructToJsonObjectString that allows a print policy to be specified.

UStructToJsonAttributes()

bool FJsonObjectConverter::UStructToJsonAttributes ( const UStruct *  StructDefinition, const void *  Struct, TMap< FString, TSharedPtr< FJsonValue > > &  OutJsonAttributes, int64  CheckFlags = 0, int64  SkipFlags = 0, const CustomExportCallback *  ExportCb = nullptr, EJsonObjectConversionFlags  ConversionFlags = EJsonObjectConversionFlags::None  )

static

Converts from a UStruct to a set of json attributes (possibly from within a JsonObject)

Parameters

StructDefinition	UStruct definition that is looked over for properties
Struct	The UStruct instance to copy out of
OutJsonAttributes	Map of attributes to copy in to
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
ExportCb	Optional callback to override export behavior, if this returns null it will fallback to the default
ConversionFlags	Bitwise flags to customize the conversion behavior

Returns

False if any properties failed to write

UStructToJsonObject() [1/2]

template<typename InStructType >

static TSharedPtr< FJsonObject > FJsonObjectConverter::UStructToJsonObject ( const InStructType &  InStruct, int64  CheckFlags = 0, int64  SkipFlags = 0, const CustomExportCallback *  ExportCb = nullptr  )

inlinestatic

Templated version of UStructToJsonObject to try and make most of the params. Also serves as an example use case

Parameters

InStruct	The UStruct instance to read from
ExportCb	Optional callback to override export behavior, if this returns null it will fallback to the default
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags

Returns

FJsonObject pointer. Invalid if an error occurred.

UStructToJsonObject() [2/2]

bool FJsonObjectConverter::UStructToJsonObject ( const UStruct *  StructDefinition, const void *  Struct, TSharedRef< FJsonObject >  OutJsonObject, int64  CheckFlags = 0, int64  SkipFlags = 0, const CustomExportCallback *  ExportCb = nullptr, EJsonObjectConversionFlags  ConversionFlags = EJsonObjectConversionFlags::None  )

static

Converts from a UStruct to a Json Object, using exportText

Parameters

StructDefinition	UStruct definition that is looked over for properties
Struct	The UStruct instance to copy out of
OutJsonObject	Json Object to be filled in with data from the ustruct
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
ExportCb	Optional callback to override export behavior, if this returns null it will fallback to the default
ConversionFlags	Bitwise flags to customize the conversion behavior

Returns

False if any properties failed to write

UStructToJsonObjectString() [1/2]

template<typename InStructType >

static bool FJsonObjectConverter::UStructToJsonObjectString ( const InStructType &  InStruct, FString &  OutJsonString, int64  CheckFlags = 0, int64  SkipFlags = 0, int32  Indent = 0, const CustomExportCallback *  ExportCb = nullptr, bool  bPrettyPrint = true  )

inlinestatic

Templated version; Converts from a UStruct to a json string containing an object, using exportText

Parameters

InStruct	The UStruct instance to copy out of
OutJsonString	Json Object to be filled in with data from the ustruct
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
Indent	How many tabs to add to the json serializer
ExportCb	Optional callback to override export behavior, if this returns null it will fallback to the default
bPrettyPrint	Option to use pretty print (e.g., adds line endings) or condensed print

Returns

False if any properties failed to write

UStructToJsonObjectString() [2/2]

bool FJsonObjectConverter::UStructToJsonObjectString ( const UStruct *  StructDefinition, const void *  Struct, FString &  OutJsonString, int64  CheckFlags = 0, int64  SkipFlags = 0, int32  Indent = 0, const CustomExportCallback *  ExportCb = nullptr, bool  bPrettyPrint = true  )

static

Converts from a UStruct to a json string containing an object, using exportText

Parameters

StructDefinition	UStruct definition that is looked over for properties
Struct	The UStruct instance to copy out of
JsonObject	Json Object to be filled in with data from the ustruct
CheckFlags	Only convert properties that match at least one of these flags. If 0 check all properties.
SkipFlags	Skip properties that match any of these flags
Indent	How many tabs to add to the json serializer
ExportCb	Optional callback to override export behavior, if this returns null it will fallback to the default
bPrettyPrint	Option to use pretty print (e.g., adds line endings) or condensed print

Returns

False if any properties failed to write

Member Data Documentation

ExportCallback_WriteISO8601Dates

const FJsonObjectConverter::CustomExportCallback FJsonObjectConverter::ExportCallback_WriteISO8601Dates

static

Initial value:

= 
    FJsonObjectConverter::CustomExportCallback::CreateLambda(
        [](FProperty* Prop, const void* Data) -> TSharedPtr<FJsonValue>
        {
            if (FStructProperty* StructProperty = CastField<FStructProperty>(Prop))
            {
                checkSlow(StructProperty->Struct);
                if (StructProperty->Struct->GetFName() == NAME_DateTime)
                {
                    return MakeShared<FJsonValueString>(static_cast<const FDateTime*>(Data)->ToIso8601());
                }
            }
            return {};
        })

---

The documentation for this class was generated from the following files:

• Engine/Source/Runtime/JsonUtilities/Public/JsonObjectConverter.h
• Engine/Source/Runtime/JsonUtilities/Private/JsonObjectConverter.cpp