Json.Reader¶

Subclasses:	None

Methods¶

Inherited:	GObject.Object (37)
Structs:	GObject.ObjectClass (5)

class	`new` (node)
	`count_elements` ()
	`count_members` ()
	`end_element` ()
	`end_member` ()
	`get_boolean_value` ()
	`get_double_value` ()
	`get_error` ()
	`get_int_value` ()
	`get_member_name` ()
	`get_null_value` ()
	`get_string_value` ()
	`get_value` ()
	`is_array` ()
	`is_object` ()
	`is_value` ()
	`list_members` ()
	`read_element` (index_)
	`read_member` (member_name)
	`set_root` (root)

Virtual Methods¶

Inherited:	GObject.Object (7)

Properties¶

Name	Type	Flags	Short Description
`root`	`Json.Node`	r/w/c	The root of the tree to read

Signals¶

Inherited:	GObject.Object (1)

Fields¶

Inherited:	GObject.Object (1)

Name	Type	Access	Description
parent_instance	`GObject.Object`	r

Class Details¶

class Json.Reader(**kwargs)¶

Bases:	`GObject.Object`
Abstract:	No
Structure:	`Json.ReaderClass`

The JsonReader structure contains only private data and should be accessed using the provided API

New in version 0.12.

classmethod new(node)¶

Parameters:	node (`Json.Node` or `None`) – a `Json.Node`, or `None`
Returns:	the newly created `Json.Reader`. Use `GObject.Object.unref`() to release the allocated resources when done
Return type:	`Json.Reader`

Creates a new Json.Reader. You can use this object to read the contents of the JSON tree starting from node

New in version 0.12.

count_elements()¶

Returns:	the number of elements, or -1. In case of failure the `Json.Reader` is set in an error state
Return type:	`int`

Counts the elements of the current position, if self is positioned on an array

New in version 0.12.

count_members()¶

Returns:	the number of members, or -1. In case of failure the `Json.Reader` is set in an error state
Return type:	`int`

Counts the members of the current position, if self is positioned on an object

New in version 0.12.

end_element()¶

Moves the cursor back to the previous node after being positioned inside an array

This function resets the error state of self, if any was set

New in version 0.12.

end_member()¶

Moves the cursor back to the previous node after being positioned inside an object

This function resets the error state of self, if any was set

New in version 0.12.

get_boolean_value()¶

Returns:	the boolean value
Return type:	`bool`

Retrieves the boolean value of the current position of self

New in version 0.12.

get_double_value()¶

Returns:	the floating point value
Return type:	`float`

Retrieves the floating point value of the current position of self

New in version 0.12.

get_error()¶

Returns:	the pointer to the error, or `None`
Return type:	`GLib.Error` or `None`

Retrieves the GLib.Error currently set on self, if the Json.Reader is in error state

New in version 0.12.

get_int_value()¶

Returns:	the integer value
Return type:	`int`

Retrieves the integer value of the current position of self

New in version 0.12.

get_member_name()¶

Returns:	the name of the member, or `None`
Return type:	`str` or `None`

Retrieves the name of the current member.

New in version 0.14.

get_null_value()¶

Returns:	`True` if ‘null’ is set, and `False` otherwise
Return type:	`bool`

Checks whether the value of the current position of self is ‘null’

New in version 0.12.

get_string_value()¶

Returns:	the string value
Return type:	`str`

Retrieves the string value of the current position of self

New in version 0.12.

get_value()¶

Returns:	a `Json.Node`, or `None`. The returned node is owned by the `Json.Reader` and it should not be modified or freed directly
Return type:	`Json.Node` or `None`

Retrieves the Json.Node of the current position of self

New in version 0.12.

is_array()¶

Returns:	`True` if the `Json.Reader` is on an array, and `False` otherwise
Return type:	`bool`

Checks whether the self is currently on an array

New in version 0.12.

is_object()¶

Returns:	`True` if the `Json.Reader` is on an object, and `False` otherwise
Return type:	`bool`

Checks whether the self is currently on an object

New in version 0.12.

is_value()¶

Returns:	`True` if the `Json.Reader` is on a value, and `False` otherwise
Return type:	`bool`

Checks whether the self is currently on a value

New in version 0.12.

list_members()¶

Returns:	a newly allocated, `None`-terminated array of strings holding the members name. Use `GLib.strfreev`() when done.
Return type:	[`str`]

Retrieves a list of member names from the current position, if self is positioned on an object.

New in version 0.14.

read_element(index_)¶

Parameters:	index (`int`) – the index of the element
Returns:	`True` on success, and `False` otherwise
Return type:	`bool`

Advances the cursor of self to the element index_ of the array or the object at the current position.

You can use the Json.Reader.get_value family of functions to retrieve the value of the element; for instance:

json_reader_read_element (reader, 0);
int_value = json_reader_get_int_value (reader);

After reading the value, Json.Reader.end_element() should be called to reposition the cursor inside the Json.Reader, e.g.:

json_reader_read_element (reader, 1);
str_value = json_reader_get_string_value (reader);
json_reader_end_element (reader);

json_reader_read_element (reader, 2);
str_value = json_reader_get_string_value (reader);
json_reader_end_element (reader);

If self is not currently on an array or an object, or if the index_ is bigger than the size of the array or the object, the Json.Reader will be put in an error state until Json.Reader.end_element() is called. This means that if used conditionally, Json.Reader.end_element() must be called on both code paths:

if (!json_reader_read_element (reader, 1))
  {
    json_reader_end_element (reader);
    g_set_error (error, …);
    return FALSE;
  }

str_value = json_reader_get_string_value (reader);
json_reader_end_element (reader);

New in version 0.12.

read_member(member_name)¶

Parameters:	member_name (`str`) – the name of the member to read
Returns:	`True` on success, and `False` otherwise
Return type:	`bool`

Advances the cursor of self to the member_name of the object at the current position.

You can use the Json.Reader.get_value family of functions to retrieve the value of the member; for instance:

json_reader_read_member (reader, "width");
width = json_reader_get_int_value (reader);

After reading the value, Json.Reader.end_member() should be called to reposition the cursor inside the Json.Reader, e.g.:

json_reader_read_member (reader, "author");
author = json_reader_get_string_value (reader);
json_reader_end_member (reader);

json_reader_read_member (reader, "title");
title = json_reader_get_string_value (reader);
json_reader_end_member (reader);

If self is not currently on an object, or if the member_name is not defined in the object, the Json.Reader will be put in an error state until Json.Reader.end_member() is called. This means that if used conditionally, Json.Reader.end_member() must be called on both code paths:

if (!json_reader_read_member (reader, "title"))
  {
    json_reader_end_member (reader);
    g_set_error (error, …);
    return FALSE;
  }

str_value = json_reader_get_string_value (reader);
json_reader_end_member (reader);

New in version 0.12.

set_root(root)¶

Parameters:	root (`Json.Node` or `None`) – a `Json.Node`

Sets the root Json.Node to be read by self. The self will take a copy of root

If another Json.Node is currently set as root, it will be replaced.

New in version 0.12.

Property Details¶

Json.Reader.props.root¶

Name:	`root`
Type:	`Json.Node`
Default Value:	`None`
Flags:	`READABLE`, `WRITABLE`, `CONSTRUCT`

The root of the JSON tree that the Json.Reader should read.

New in version 0.12.