[gom] gom: Add better check on the primary-key property

[Bastien Nocera <hadess src gnome org>]

commit f416919a96d6fc087c01b9fdf1bec9d624790ec9
Author: Bastien Nocera <hadess hadess net>
Date:   Tue May 6 21:39:43 2014 +0200

    gom: Add better check on the primary-key property
    
    Make sure that the primary-key property isn't set as a construct-only
    property, or that its default value is non-NULL.
    
    Thanks to Mathieu Bridon for the code that needed those checks :)

 gom/gom-resource.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)
---
diff --git a/gom/gom-resource.c b/gom/gom-resource.c
index 225e8db..f138031 100644
--- a/gom/gom-resource.c
+++ b/gom/gom-resource.c
@@ -47,9 +47,31 @@ void
 gom_resource_class_set_primary_key (GomResourceClass *resource_class,
                                     const gchar      *primary_key)
 {
+   GParamSpec *pspec;
+   const GValue *value;
+
    g_return_if_fail(GOM_IS_RESOURCE_CLASS(resource_class));
    g_return_if_fail(primary_key != NULL);
 
+   pspec = g_object_class_find_property(G_OBJECT_CLASS(resource_class), primary_key);
+   if (!pspec) {
+      g_warning("Property for primary key '%s' isn't declared yet. Are you running 
gom_resource_class_set_primary_key() too early?",
+                primary_key);
+      return;
+   }
+
+   if (pspec->flags & G_PARAM_CONSTRUCT_ONLY) {
+      g_warning("Property for primary key '%s' is declared as construct-only. This will not work as 
expected.", primary_key);
+      return;
+   }
+
+   /* Same check as in has_primary_key() */
+   value = g_param_spec_get_default_value (pspec);
+   if (value->data[0].v_pointer) {
+      g_warning("Property for primary key '%s' has a non-NULL/non-zero default value. This will not work as 
expected.", primary_key);
+      return;
+   }
+
    g_snprintf(resource_class->primary_key,
               sizeof(resource_class->primary_key),
               "%s", primary_key);