Reader

json.reader.Reader provides a simple, cursor-based API for parsing a JSON DOM.

It is similar, in spirit, to the XML Reader API.

Using json.reader.Reader

g_autoptr(JsonParser) parser = json_parser_new ();

// str is defined elsewhere
json_parser_load_from_data (parser, str, -1, NULL);

g_autoptr(JsonReader) reader = json_reader_new (json_parser_get_root (parser));

json_reader_read_member (reader, "url");
  const char *url = json_reader_get_string_value (reader);
  json_reader_end_member (reader);

json_reader_read_member (reader, "size");
  json_reader_read_element (reader, 0);
    int width = json_reader_get_int_value (reader);
    json_reader_end_element (reader);
  json_reader_read_element (reader, 1);
    int height = json_reader_get_int_value (reader);
    json_reader_end_element (reader);
  json_reader_end_member (reader);

Error handling

In case of error, json.reader.Reader will be set in an error state; all subsequent calls will simply be ignored until a function that resets the error state is called, e.g.:

// ask for the 7th element; if the element does not exist, the
// reader will be put in an error state
json_reader_read_element (reader, 6);

// in case of error, this will return NULL, otherwise it will
// return the value of the element
str = json_reader_get_string_value (value);

// this function resets the error state if any was set
json_reader_end_element (reader);

If you want to detect the error state as soon as possible, you can use json.reader.Reader.getError:

// like the example above, but in this case we print out the
// error immediately
if (!json_reader_read_element (reader, 6))
  {
    const GError *error = json_reader_get_error (reader);
    g_print ("Unable to read the element: %s", error->message);
  }

Constructors

this this(json.node.Node node): Creates a new reader.

Members

Functions

countElements int countElements(): Counts the elements of the current position, if the reader is positioned on an array.
countMembers int countMembers(): Counts the members of the current position, if the reader is positioned on an object.
endElement void endElement(): Moves the cursor back to the previous node after being positioned inside an array.
endMember void endMember(): Moves the cursor back to the previous node after being positioned inside an object.
getBooleanValue bool getBooleanValue(): Retrieves the boolean value of the current position of the reader.
getCurrentNode json.node.Node getCurrentNode(): Retrieves the reader node at the current position.
getDoubleValue double getDoubleValue(): Retrieves the floating point value of the current position of the reader.
getError glib.error.ErrorG getError(): Retrieves the error currently set on the reader.
getIntValue long getIntValue(): Retrieves the integer value of the current position of the reader.
getMemberName string getMemberName(): Retrieves the name of the current member.
getNullValue bool getNullValue(): Checks whether the value of the current position of the reader is null.
getStringValue string getStringValue(): Retrieves the string value of the current position of the reader.
getValue json.node.Node getValue(): Retrieves the value node at the current position of the reader.
isArray bool isArray(): Checks whether the reader is currently on an array.
isObject bool isObject(): Checks whether the reader is currently on an object.
isValue bool isValue(): Checks whether the reader is currently on a value.
listMembers string[] listMembers(): Retrieves a list of member names from the current position, if the reader is positioned on an object.
readElement bool readElement(uint index): Advances the cursor of the reader to the element of the array or the member of the object at the given position.
readMember bool readMember(string memberName): Advances the cursor of the reader to the member_name of the object at the current position.
setRoot void setRoot(json.node.Node root): Sets the root node of the JSON tree to be read by reader.

Inherited Members

From ObjectG

setGObject void setGObject(void* cObj, Flag!"Take" take): Set the GObject of a D ObjectG wrapper.
cPtr void* cPtr(Flag!"Dup" dup): Get a pointer to the underlying C object.
ref_ void* ref_(void* gObj): Calls g_object_ref() on a GObject.
unref unref(void* gObj): Calls g_object_unref() on a GObject.
getType GType getType(): Get the GType of an object.
gType GType gType [@property getter]: GObject GType property.
self ObjectG self(): Convenience method to return this cast to a type. For use in D with statements.
getDObject T getDObject(void* cptr, Flag!"Take" take): Template to get the D object from a C GObject and cast it to the given D object type.
connectSignalClosure ulong connectSignalClosure(string signalDetail, DClosure closure, Flag!"After" after): Connect a D closure to an object signal.
setProperty void setProperty(string propertyName, T val): Template for setting a GObject property.
getProperty T getProperty(string propertyName): Template for getting a GObject property.
compatControl size_t compatControl(size_t what, void* data)
bindProperty gobject.binding.Binding bindProperty(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags): Creates a binding between source_property on source and target_property on target.
bindPropertyFull gobject.binding.Binding bindPropertyFull(string sourceProperty, gobject.object.ObjectG target, string targetProperty, gobject.types.BindingFlags flags, gobject.closure.Closure transformTo, gobject.closure.Closure transformFrom): Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.
forceFloating void forceFloating(): This function is intended for #GObject implementations to re-enforce a floating[floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling gobject.object.ObjectG.refSink.
freezeNotify void freezeNotify(): Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one #GObject::notify signal is emitted for each property modified while the object is frozen.
getData void* getData(string key): Gets a named field from the objects table of associations (see gobject.object.ObjectG.setData).
getProperty void getProperty(string propertyName, gobject.value.Value value): Gets a property of an object.
getQdata void* getQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata.
getv void getv(string[] names, gobject.value.Value[] values): Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.
isFloating bool isFloating(): Checks whether object has a floating[floating-ref] reference.
notify void notify(string propertyName): Emits a "notify" signal for the property property_name on object.
notifyByPspec void notifyByPspec(gobject.param_spec.ParamSpec pspec): Emits a "notify" signal for the property specified by pspec on object.
refSink gobject.object.ObjectG refSink(): Increase the reference count of object, and possibly remove the floating[floating-ref] reference, if object has a floating reference.
runDispose void runDispose(): Releases all references to other objects. This can be used to break reference cycles.
setData void setData(string key, void* data): Each object carries around a table of associations from strings to pointers. This function lets you set an association.
setProperty void setProperty(string propertyName, gobject.value.Value value): Sets a property on an object.
stealData void* stealData(string key): Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
stealQdata void* stealQdata(glib.types.Quark quark): This function gets back user data pointers stored via gobject.object.ObjectG.setQdata and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:
thawNotify void thawNotify(): Reverts the effect of a previous call to gobject.object.ObjectG.freezeNotify. The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.
watchClosure void watchClosure(gobject.closure.Closure closure): This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling gobject.closure.Closure.invalidate on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, gobject.object.ObjectG.ref_ and gobject.object.ObjectG.unref are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.
connectNotify ulong connectNotify(string detail, T callback, Flag!"After" after): Connect to Notify signal.

json reader classes

Reader