Build a Tree

The parse() method takes input from an XML file object and builds a hierarchical tree as a collection of elements. Each element may have multiple child elements or no child elements. The root element is instantiated by the getroot() method (Listing 3).

tree = ET.parse(xmlinfile)
root = tree.getroot()

Track Dictionary

Track metadata is a hybrid of nested lists and dictionaries with key-value pairs. The dictionary containing the metadata is nested two levels below the root. The find() method in the two statements shown in Listing 4 finds the next level descendant with a <dict> tag.

dict_gen1 = root.find('dict')
dict_gen2 = dict_gen1.find('dict')

The second-generation dictionary contains a list of all track dictionaries in the library or playlist. After locating the track dictionaries, you can work on the child elements that contain the metadata for each track.

Element Tags and Text

To get the track metadata, you need to find the track metadata tags and then retrieve the text from those tags. The statement in Listing 5 uses the findall() method to find all child elements of each track dictionary beneath dict_gen2 and creates a list object named tracklist that contains a list of dictionaries.

tracklist=list(dict_gen2.findall('dict'))

Next extract from tracklist nested lists of child elements that have track metadata. Not all <dict> tags will contain the metadata that you want, so you can use the Artist text string of the <key> tag to identify the desired dictionaries. See Figure 2 and Listing 6. The element text is accessed with the element.text attribute.

itunes_music = []
for item in tracklist:
    x = list(item)
    for i in range( len(x) ):
        if x[i].text == "Artist":
            itunes_music.append( list(item) )

Figure 2: Tag and text.

The itunes_music list object is a list of all song tracks contained in the input XML file. At this point, you may want to inspect the resulting metadata in the itunes_music list. Each <key> tag is followed by the corresponding <string> or <integer> tag. The code in Listing 7 assumes that the tagtrue() function was previously defined (for brevity, code not shown here), tests for <key> tag text that matches the desired metadata strings (Figure 3), and then prints the key and value pair text strings to your screen.

for i in range(len(itunes_music)):
    for j in range(len(itunes_music[i])):
        if tagtrue(itunes_music[i][j].text):
            print(itunes_music[i][j].text\
                , itunes_music[i][j+1].text)

Figure 3: Loop index rows and columns.

After confirming the metadata, you can then utilize it as you need. Because the list is organized as a two-dimensional array, I will represent it in table form as it would appear in a spreadsheet or database table (Figure 3). Note that the i loop (or outer loop variable) represents rows, and the j loop (or inner loop variable) represents columns.