Class Poco::JSON::Object

File Information

Library: JSON
Package: JSON
Header: Poco/JSON/Object.h

Description

Represents a JSON object. Object provides a representation based on shared pointers and optimized for performance. It is possible to convert Object to DynamicStruct. Conversion requires copying and therefore has performance penalty; the benefit is in improved syntax, eg:

std::string json = "{ \"test\" : { \"property\" : \"value\" } }";
Parser parser;
Var result = parser.parse(json);

// use pointers to avoid copying
Object::Ptr object = result.extract<Object::Ptr>();
Var test = object->get("test"); // holds { "property" : "value" }
Object::Ptr subObject = test.extract<Object::Ptr>();
test = subObject->get("property");
std::string val = test.toString(); // val holds "value"

// copy/convert to Poco::DynamicStruct
Poco::DynamicStruct ds = *object;
val = ds["test"]["property"]; // val holds "value"

Member Summary

Member Functions: begin, clear, end, get, getArray, getEscapeUnicode, getLowercaseHex, getNames, getNullableValue, getObject, getValue, has, isArray, isNull, isObject, makeOrderedStruct, makeStruct, operator =, optValue, remove, set, setEscapeUnicode, setLowercaseHex, size, stringify

Types Aliases

ConstIterator

using ConstIterator = ValueMap::const_iterator;

Iterator

using Iterator = ValueMap::iterator;

NameList

using NameList = std::vector < std::string >;

Ptr

using Ptr = SharedPtr < Object >;

ValueMap

using ValueMap = std::map < std::string, Dynamic::Var >;

ValueType

using ValueType = ValueMap::value_type;

Constructors

Object

explicit Object(
int options = 0
);

Creates an empty Object.

If JSON_PRESERVE_KEY_ORDER is specified, the object will preserve the items insertion order. Otherwise, items will be sorted by keys.

If JSON_ESCAPE_UNICODE is specified, when the object is stringified, all unicode characters will be escaped in the resulting string.

Object

Object(
const Object & copy
);

Creates an Object by copying another one.

Struct is not copied to keep the operation as efficient as possible (when needed, it will be generated upon request).

Object

Object(
Object && other
) noexcept;

Move constructor

Destructor

~Object

~Object();

Destroys the Object.

Member Functions

begin

Iterator begin();

Returns begin iterator for values.

begin

ConstIterator begin() const;

Returns const begin iterator for values.

clear

void clear();

Cast operator to Poco::OrderedDynamiStruct. Cast operator to Poco::DynamiStruct. Clears the contents of the object.

Insertion order preservation property is left intact.

end

Iterator end();

Returns end iterator for values.

end

ConstIterator end() const;

Returns const end iterator for values.

get

Dynamic::Var get(
const std::string & key
) const;

Retrieves a property. An empty value is returned when the property doesn't exist.

getArray

Array::Ptr getArray(
const std::string & key
) const;

Returns a SharedPtr to an array when the property is an array. An empty SharedPtr is returned when the element doesn't exist or is not an array.

getEscapeUnicode

bool getEscapeUnicode() const;

Returns the flag for escaping unicode.

getLowercaseHex

bool getLowercaseHex() const;

Returns the flag for using lowercase hex numbers

getNames

void getNames(
NameList & names
) const;

Fills the supplied vector with all property names.

getNames

NameList getNames() const;

Returns all property names.

getNullableValue

template < typename T > Poco::Nullable < T > getNullableValue(
const std::string & key
) const;

Retrieves the property with the given name and will try to convert the value to the given template type.

The convert<T> method of Var is called which can also throw exceptions for invalid values. Note: This will not work for an array or an object.

getObject

Object::Ptr getObject(
const std::string & key
) const;

Returns a SharedPtr to an object when the property is an object. An empty SharedPtr is returned when the property doesn't exist or is not an object

getValue

template < typename T > T getValue(
const std::string & key
) const;

Retrieves the property with the given name and will try to convert the value to the given template type. The convert<T>() method of Var is called which can also throw exceptions for invalid values. Note: This will not work for an array or an object.