Does anyone have any pointers?
Thank you.
On Fri, Feb 22, 2019 at 11:58 AM Mitko Haralanov <voidtrance@xxxxxxxxx> wrote:
>
> Hi,
>
> I've been trying to figure out how to use GVariantBuilder to build a
> complex structure with little success. The type of structure that I
> would like to build is meant to partially encode a GtkTreeModel
> structure. So, I thought that I could use GVariantBuilder to build a
> structure of nested dictionaries.
>
> The structure roughly follows this model:
> [
> {
> "id": { "key1": (<int>, <string>, ...), "children": [
> { "id2" : { "key1" : (<int>, <string>, ...),
> "children" : []},
> { "id3" : { "key1" : (<int>, <string>, ...),
> "children" : [
> { ... }
> ]}
> ]}},
> { "id" : ...}
> ]
>
> This type of encoding can naturally be done with recursion and using
> multiple GVariantBuilder's to add to the correct parent. However, I am
> having difficulty with getting the formatting strings correct. As it
> turns out, GLib insist on every dictionary entry being statically
> typed meaning that the values for both "key1" and "children" has to be
> of the same type. That seems to leave only 'v' as a valid format. So,
> I have the following code (only important parts are pasted, not a
> complete program):
>
> struct tree_entry_search {
> uint32_t type;
> const char *term;
> };
>
> struct tree_entry {
> const char *id;
> struct tree_entry_search search;
> GList *children;
> };
>
> void add_elem(GVariantBuilder *builder, struct tree_entry *elem)
> {
> GVariantBuilder *new, *child_builder;
> GVariant *new_dict, *new_array, *search;
> GList *item;
>
> new = g_variant_builder_new(G_VARIANT_TYPE_DICTIONARY);
> search = g_variant_new("(us)", elem->search.type, elem->search.term);
> g_variant_builder_add(new, "{sv}", "search", search);
> child_builder = g_variant_builder_new(G_VARIANT_TYPE("av"));
> for (item = elem->children; item; item = item->next)
> add_elem(child_builder, item->data);
> new_array = g_variant_builder_end(child_builder);
> g_variant_builder_unref(child_builder);
> g_variant_builder_add(new, "{sv}", "children", new_array);
> new_dict = g_variant_builder_end(new);
> g_variant_builder_unref(new);
> g_variant_builder_add(builder, "{sv}", elem->id, new_dict);
> }
>
> int main(void) {
> ...
> /* Build up a fake tree. */
> root.id = g_strdup("uid1");
> root.search.type = 1;
> root.search.term = g_strdup("term1");
> elem = g_new0(struct tree_entry, 1);
> elem->id = g_strdup("uid2");
> elem->search.type = 2;
> elem->search.term = g_strdup("term2");
> root.children = g_list_append(root.children, elem);
> elem = g_new0(struct tree_entry, 1);
> elem->id = g_strdup("uid3");
> elem->search.type = 2;
> elem->search.term = g_strdup("term3");
> root.children = g_list_append(root.children, elem);
> child = g_new0(struct tree_entry, 1);
> child->id = g_strdup("uid4");
> child->search.type = 3;
> child->search.term = g_strdup("term4");
> elem->children = g_list_append(elem->children, child);
>
> builder = g_variant_builder_new(G_VARIANT_TYPE_ARRAY);
> add_elem(builder, &root);
> dict = g_variant_builder_end(builder);
> dictionary = g_variant_print(dict, TRUE);
> printf("%s\n", dictionary);
> ...
> }
>
> But when I compile the above and run it, I get the following errors
> when the tree is more than one level deep:
>
> (process:3873): GLib-CRITICAL **: 11:44:03.826:
> g_variant_builder_add_value: assertion '!GVSB(builder)->expected_type
> || g_variant_is_of_type (value, GVSB(builder)->expected_type)' failed
>
> (process:3873): GLib-CRITICAL **: 11:44:03.827:
> g_variant_builder_add_value: assertion '!GVSB(builder)->expected_type
> || g_variant_is_of_type (value, GVSB(builder)->expected_type)' failed
>
> (process:3873): GLib-CRITICAL **: 11:44:03.827:
> g_variant_builder_add_value: assertion '!GVSB(builder)->expected_type
> || g_variant_is_of_type (value, GVSB(builder)->expected_type)' failed
>
> What's the correct way to specify the builder and variant types so I
> can build the nested dictionary structure?
>
> Thank you for the help.
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