La traducció d'aquesta pàgina encara no està acabada. Fins que ho sigui, algunes part correspondrà a la versió anglesa.
Creating a custom filetype
File recognition
Preferred Application
Extra Attributes
Filling in the data
Querying the database

Tutorial: Tipus de fitxers, Atributs, Índex i Consultes

This is a workshop to show the use of Attributes, Queries, the Index and custom Filetypes. As an example, we build a database to keep track of our DVD library.

index Preparació

Let's first decide what filetype and attributes would serve our needs. Originally, I planned to use a bookmark file with a link to the movie's IMdB page, but since Haiku didn't have a "bookmarkable" browser like BeOS' NetPositive at that time, I came up with this: The file itself will be a JPEG image for the movie cover.
With WebPositive, Haiku now has a browser using bookmark files again, so you could as well use a bookmark file instead of an image as basic filetype for our database files.
In any case, to these files we add a couple of attributes. Here we have to decide if we want to query it later (then we have to add it to the index) and if so, what type of attribute it should be. Numbers (int, float) can be evaluated differently than text (</=/> vs. is/contains/starts with).

Here are the attributes I'd like to see for my DVDs:

index Generar un nou tipus de fitxer

Start the Filetypes preferences, and click on the Add… button below the hierarchical list on the left. A small dialog opens and you specify in which MIME Group your new filetype will reside. You can also create a completely new group. Let's put it into "applications" and set the "Internal name" to DVDdb.


Now, a panel for your new DVDdb filetype opens:


index Icona

Double-click the icon well to open Icon-O-Matic to design an icon for your filetype. You can also drag & drop an icon from the icon well of another type, maybe as starting point for a modified version.

index Reconeixement de fitxers

You can add suffixes like .txt, .jpg, .mp3 to recognize files by their extention. Useful when working with files from systems without MIME typing. We don't need that for our example.

index Descripció

index Aplicació Preferida

This pop-up menu shows a list of all applications that can handle this particular filetype. From here you can choose which program should open this specific file when it's double-clicked.

Trieu... opens a file dialog where you choose the application to open with this filetype. Here, we set ShowImage to display the DVD's cover.
Igual que... opens a file dialog where you choose any file that already has the preferred application set that you're looking for.

index Altres Atributs

Here we enter all the custom attributes we decided on in our preparations. Clicking the Add… button opens a panel to enter all the data for the new attribute. You can edit an existing attribute with a double-click.


Now, insert all the info for our attributes:

Nom InternTipus d'atributEstà indexat?Descripció
DVDdb:title text Títol de la película
DVDdb:genre text Gènere
DVDdb:url text no URL
DVDdb:cast text Director/Repartiment
DVDdb:plot text no Plot
DVDdb:rating int-32 Valoració de 1 a 10
DVDdb:coord text no Prestatge
DVDdb:lent text Deixat a

index Indexat

Before we start entering data in our little DVD database, we should add certain attributes to the Index. Only indexed attributes can use Haiku's fast Queries.
So, what will we be searching in the future? We probably won't ask "What's in the B4 coordinate in my shelf?" or "Does the IMdB URL or the plot of the movie contain the word 'pope-shenooda'?".

This leaves these attributes:

Nom InternTipus d'atribut

To index them, we open a Terminal and simply add one attribute after the other:

mkindex -t string DVDdb:title
mkindex -t string DVDdb:genre
mkindex -t string DVDdb:cast
mkindex -t int DVDdb:rating

The -t option defines the type of attribute, which is "string" for all but the rating, which is an integer number.

index Omplint les dades

Now, everything's set and we can begin putting some data into our base.
Since our basic file is a cover image, we go to some online resource like IMdB, look for our first movie and save the cover or movie poster in a new folder where we want to keep our DVDdb files.

Opening that folder we see a typical Tracker window with one JPEG in it. Right-clicking it, we change its filetype to application/DVDdb with the Filetype Addon. There's more info on this in the Filetypes document.

Now, we activate all our DVDdb attributes from the Attributes menu of the Tracker window and rearrange the columns to our taste:


By clicking on a yet empty attribute (or pressing ALT E) we enter editing mode and fill each attribute. With TAB and SHIFT TAB you can navigate between attributes.

In our example, we usually start with a downloaded JPG cover and change its type to applications/DVDdb. There's another elegant way to produce a file to work with. Just copy an empty file of our filetype to /boot/home/config/settings/Tracker/Tracker New Templates and rename it to DVDdb.

Right-clicking into a Tracker window, you'll find a new entry under New… besides the default "New folder".

index Consultar la base de dades

Several hours of grunt work later, we have a nice little database that you can query to find all your Christina Ricci movies that have a 7 rating… :)

You can assign a sensible attribute layout for query results of a specific filetype.
Open the folder containing your DVDdb files and arrange the attributes how you'd like to have query results presented. Copy this layout with Attributes | Copy layout.

Open /boot/home/config/settings/Tracker/DefaultQueryTemplates, create a new folder and rename it to group/filetype, replacing slashes with underscores; in our case "application_DVDdb".

Open the new folder and paste in the layout with Attributes | Paste layout. Voilà: