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Topic: Watching tag edits to update metadb hashes (Read 1152 times) previous topic - next topic
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Watching tag edits to update metadb hashes

So thanks to Peter's help I've been able to get my plugin working correctly with creating a metadb, and storing values in it based on a hash.  Now what I need is a way to move the data in the metadb from the old to new hash when tag content changes (I'm trying to emulate foo_playcount's behavior).

I'm using metadb_io_edit_callback because I need before and after values. Here's what I've got so far:

Code: [Select]
	class metadb_io_edit_callback_impl : public metadb_io_edit_callback {
	public:
		typedef const pfc::list_base_const_t<const file_info*> & t_infosref;
		void on_edited(metadb_handle_list_cref items, t_infosref before, t_infosref after) {
			for (size_t t = 0; t < items.get_count(); t++) {
				metadb_handle_ptr p_item = items[t];
				file_info_impl info;
				if (p_item->get_info(info)) {
					pfc::string8 artist;
					pfc::string8 album;
					pfc::string8 title;
					artist = info.meta_get("ARTIST", 0);
					album = info.meta_get("ALBUM", 0);
					title = info.meta_get("TITLE", 0);
					metadb_index_hash hash;
					g_client->hashHandle(p_item, hash);
					FB2K_console_formatter() << artist << " - " << album << " - " << title << " - " << hash;

					artist = after[t]->meta_get("ARTIST", 0);
					album = after[t]->meta_get("ALBUM", 0);
					title = after[t]->meta_get("TITLE", 0);
					FB2K_console_formatter() << "after: " << artist << " - " << album << " - " << title;
				}
			}
		}
	};

	static service_factory_single_t<metadb_io_edit_callback_impl> g_my_metadb_io;

This works great so far. Calling meta_get on the entries in metadb_handle_list_cref spits out the old pre-edit values just fine, and because it's the old values I can only assume that the hash is the pre-edit hash. Calling meta_get() on the after[t] also returns the post-edit values. I'm logging to the console for sanity purposes and it all looks correct.

Where I'm stuck now is I'm not sure how to actually take the file_info* I get from after[t] and turn that into the new hash. Maybe I have to do this manually the same way it's done in the metadb_index_client::transform() I have?

I obviously also need to figure out how to copy the value at the old hash and store it at the new hash, but I assume that's mostly trivial once I know what the post change hash is going to be.

Any help you guys can provide would be much appreciated.

Re: Watching tag edits to update metadb hashes

Reply #1 –
In case anyone was having the same issue I was, I figured out how to do it. I'm not 100% sure if this is the BEST way to do it, and I really hate being forced to use individual meta_get's instead of a single title format, but unless I'm missing something meta_get is the only option on a file_info*.

Code: [Select]
	class metadb_io_edit_callback_impl : public metadb_io_edit_callback {
	public:
		typedef const pfc::list_base_const_t<const file_info*> & t_infosref;
		void on_edited(metadb_handle_list_cref items, t_infosref before, t_infosref after) {
			static static_api_ptr_t<metadb_index_manager> api;	// initialized once here
			for (size_t t = 0; t < items.get_count(); t++) {
				metadb_index_hash hashOld, hashNew;

				g_client->hashHandle(items[t], hashOld);

				// my hash is pinned to "%artist% %album% $if2(%discnumber%,1) %tracknumber% %title% 
				pfc::string8 artist = meta_get_if_exists(after[t], "ARTIST", "");
				pfc::string8 album = meta_get_if_exists(after[t], "ALBUM", "");
				pfc::string8 discnum = meta_get_if_exists(after[t], "DISCNUMBER", "1");
				pfc::string8 tracknum = meta_get_if_exists(after[t], "TRACKNUMBER", "");
				pfc::string8 title = meta_get_if_exists(after[t], "TITLE", "");

				pfc::string_formatter strAfter;
				strAfter << artist << " " << album << " " << discnum << " " << tracknum << " " << title;

				hashNew = static_api_ptr_t<hasher_md5>()->process_single_string(strAfter).xorHalve();
				if (hashOld != hashNew) {
					record_t record = getRecord(hashOld, api); // this is my function for retrieving the data structure from metadb
					record_t newRecord = getRecord(hashNew, api);
					// use whatever logic you want to determine if a record at the old hash exists and whether to overwrite a record at the new hash
				}
			}
		}
	};

	static service_factory_single_t<metadb_io_edit_callback_impl> g_my_metadb_io;

	// helper function to get meta value or return default if not found. equivalent to $if2
	pfc::string8 meta_get_if_exists(const file_info * info, const char* key, const char* default) {
		if (info->meta_exists(key)) {
			return info->meta_get(key, 0);
		} 
		return default;
	}