gwutz / xml-glib

XML Serialization for GObject

XML Serialization for GObject

This library is intended to make it easier to serialize and deserialize GObject instances to XML files and back. It uses a similar serialization strategy then JSON-glib. If you don't specify special properties, then it is already capable to serialize without intervention. But you are able to implement an interface for special properties like lists, arrays and so on.

xml-glib utilizes libxml2 tree structures to build up a xml representation of your object. Therefore you have to interact with some structures from libxml2. I plan to add a dump method to handly only a string without interacting with libxml2. This is not decided at the moment.

Installation

This library gets installed typical with

# git clone https://github.com/gwutz/xml-glib.git
# cd xml-glib
# mkdir build && cd build
# meson ..
# ninja
# ninja install

Usage

The basic usage is to use

GObject *myobj = my_super_object_new ();

xmlNodePtr root = xml_gobject_serialize (myobj);
xmlDocPtr doc = xmlNewDoc ("1.0");
xmlDocSetRootElement (doc, root);

xmlDocDump (stdout, doc);

Special properties

If you want to control the output or you have special properties like a List of items, we have to implement the XmlSerializable interface to convert the property correctly (C cannot guess which pointers getting stored in a linked list - so we have to tell him)

struct _XmlSerializableInterface
{
  GTypeInterface parent;

  xmlNodePtr (* serialize_property)   (XmlSerializable *serializable,
                                       const gchar     *property_name,
                                       const GValue    *value,
                                       GParamSpec      *pspec);
  gboolean   (* deserialize_property) (XmlSerializable *serializable,
                                       const gchar     *property_name,
                                       GValue          *value,
                                       GParamSpec      *pspec,
                                       xmlNodePtr       node);
  const gchar *(* get_root_name)      (XmlSerializable *serializable);
};

The serialize_property method gets used if the interface is implemented. For standard properties you can still use the default behaviour from xml-glib. Just call xml_serializable_default_serialize_property at the end of serialize_property if you filtered your special properties. A typical implementation could look like (you can find the whole example under test/xml-addresslist.c/.h and address-test.c):

static xmlNodePtr
xml_addresslist_serialize_property (XmlSerializable *serializable,
                                    const gchar     *property_name,
                                    const GValue    *value,
                                    GParamSpec      *pspec)
{
  if (g_strcmp0 (property_name, "addresses") == 0) {
    GPtrArray *arr = g_value_get_boxed (value);
    xmlNodePtr first;

    for (int i = 0; i < arr->len; i++) {
      XmlAddress *a = g_ptr_array_index (arr, i);

      xmlNodePtr n = xml_gobject_serialize (G_OBJECT (a));
      if (i == 0) first = n;
      else xmlAddSibling (first, n);
    }

    return first;
  }

  return xml_serializable_default_serialize_property (serializable, property_name, value, pspec);
}