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Index
Pregătiri
Crearea unui tip de fișier personalizat
Pictogramă
Recunoașterea fișierelor
Descriere
Aplicația preferată
Atribute extra
Indexare
Adăugarea datelor
Interogarea bazei de date

Seminar: Tipuri de fișiere, atribute, index și interogări

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 Pregătiri

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).

Acestea sunt atributele pe care aș vrea să le văd pentru DVD-urile mele:

index Crearea unui tip de fișier personalizat

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.

filetypes-new-file-type.png

Un panou pentru noul tip de fișier DVDdb se deschide:

filetypes-dvddb.png

index Pictogramă

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 Recunoașterea fișierelor

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 Descriere

index Aplicația preferată

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.

Selectare... deschide un dialog de fișier unde alegeți aplicația de deschis cu acest tip de fișier. Aici vom stabili ShowImage ca să afișeze coperta DVD.
La fel ca... deschide un dialog de fișier unde alegeți orice fișier care are deja stabilită aplicația preferată pe care o căutați.

index Atribute extra

Aici introducem toate atributele personalizate asupra cărora ne-am decis în pregătirile precedente. Clic pe butonul Adăugare... deschide un panou pentru a introduce datele pentru atributul nou. Puteți edita un atribut existent cu dublu clic.

filetype-extra-attribute.png

Acum introduceți toate informațiile pentru atribute:

Nume internTip de atributindexat?Descriere
DVDdb:title text da Titlu film
DVDdb:genre text da Gen
DVDdb:url text nu URL
DVDdb:cast text da Director/Actori
DVDdb:plot text nu Subiect
DVDdb:rating int-32 da Evaluare 1 la 10
DVDdb:coord text nu Raft
DVDdb:lent text da Împrumutat la

index Indexare

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'?".

Aceasta lasă următoarele atribute:

Nume internTip de atribut
DVDdb:titletext
DVDdb:genretext
DVDdb:casttext
DVDdb:ratingint-32

Pentru a le indexa, deschidem un Terminal și adăugăm pur și simplu atributele unul după altul:

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

Opțiunea -t definește tipul de atribut, care e „string” pentru toate în afară de evaluare, care este un număr întreg.

index Adăugarea datelor

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:

filetypes-dvddb-empty.png

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 Interogarea bazei de date

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 "applications_DVDdb".

Deschideți un dosar nou și lipiți aranjamentul cu Atribute | Lipire aranjament. Voilà:

query-dvddb.png