XPath Style XML Selection

The xml API in scala allows xpath like (although not true xpath) queries. In combination with matching this makes it very easy to process XML documents. I am only going to discuss xpath style selection now. The code section is very long but primarily because the results are often quite lengthy.

1. scala> val address = <address>
2.      | <CI_Address>
3.      | <deliveryPoint>
4.      | <CharacterString>Viale delle Terme di Caracalla
5.      | </CharacterString>
6.      | </deliveryPoint>
7.      | <city>
8.      | <CharacterString>Rome</CharacterString>
9.      | </city>
10.      | <administrativeArea>
11.      | <CharacterString />
12.      | </administrativeArea>
13.      | <postalCode>
14.      | <CharacterString>00153</CharacterString>
15.      | </postalCode>
16.      | <country>
17.      | <CharacterString>Italy</CharacterString>
18.      | </country>
19.      | <electronicMailAddress>
20.      | <CharacterString>jippe.hoogeveen@fao.org
21.      | </CharacterString>
22.      | </electronicMailAddress>
23.      | </CI_Address>
24.      | </address>
25. address: scala.xml.Elem =
26. <address>
27.        <CI_Address>
28.       ...
30. // create a pretty printer for writing out the document nicely
31. scala>  val pp = new scala.xml.PrettyPrinter(80, 5);
32. pp: scala.xml.PrettyPrinter = scala.xml.PrettyPrinter@6d87c12a
34. // select the city
35. scala> println( pp.formatNodes( address \ "CI_Address" \ "city" ) )                   
36. <city>
37.      <gco:CharacterString>Rome</gco:CharacterString>
38. </city>
40. // a second way to select city
41. scala> println( pp.formatNodes( address \\ "city" ) )      
42. <city>
43.      <gco:CharacterString>Rome</gco:CharacterString>
44. </city>
46. // select all characterStrings and print then one per line (unless there is a \n in the text)
47. scala> (address \\ "CharacterString").mkString( "\n" )
48. res2: String =
49. <CharacterString>Viale delle Terme di Caracalla
50.        </CharacterString>
51. <CharacterString>Rome</CharacterString>
52. <CharacterString></CharacterString>
53. <CharacterString>00153</CharacterString>
54. <CharacterString>Italy</CharacterString>
55. <CharacterString>jippe.hoogeveen@fao.org
56.        </CharacterString>
58. // iterate over the city node and all of its child nodes.
59. scala> println( pp.formatNodes( address \\ "city" \\ "_"))
60. <city>
61.      <CharacterString>Rome</CharacterString>
62. </city><CharacterString>Rome</CharacterString>
64. // similar as above but iterate over all CI_Address nodes and each of its children
65. scala>println( pp.formatNodes( address \\ "CI_Address" \\ "_")) 
66. <CI_Address>
67.      <deliveryPoint>
68.           <CharacterString>Viale delle Terme di Caracalla </CharacterString>
69.      </deliveryPoint>
70.      <city>
71.           <CharacterString>Rome</CharacterString>
72.      </city>
73.      <administrativeArea>
74.           <CharacterString></CharacterString>
75.      </administrativeArea>
76.      <postalCode>
77.           <CharacterString>00153</CharacterString>
78.      </postalCode>
79.      <country>
80.           <CharacterString>Italy</CharacterString>
81.      </country>
82.      <electronicMailAddress>
83.           <CharacterString>jippe.hoogeveen@fao.org </CharacterString>
84.      </electronicMailAddress>
85. </CI_Address><deliveryPoint>
86.      <CharacterString>Viale delle Terme di Caracalla </CharacterString>
87. </deliveryPoint><CharacterString>Viale delle Terme di Caracalla </CharacterString><city>
88.      <CharacterString>Rome</CharacterString>
89. </city><CharacterString>Rome</CharacterString><administrativeArea>
90.      <CharacterString></CharacterString>
91. </administrativeArea><CharacterString></CharacterString><postalCode>
92.      <CharacterString>00153</CharacterString>
93. </postalCode><CharacterString>00153</CharacterString><country>
94.      <CharacterString>Italy</CharacterString>
95. </country><CharacterString>Italy</CharacterString><electronicMailAddress>
96.      <CharacterString>jippe.hoogeveen@fao.org </CharacterString>
97. </electronicMailAddress><CharacterString>jippe.hoogeveen@fao.org </CharacterString>
100. // print all text
101. scala> address.text                      
102. res4: String =
104.       
105.       
106.        Viale delle Terme di Caracalla
107.       
108.       
109.       
110.        Rome
111.       
112.       
113.       
114.       
115.       
116.        00153
117.       
118.       
119.        Italy
120.       
121.       
122.        jippe.hoogeveen@fao.org
123.       
124. // print all character string text
125. scala> (address \\ "CharacterString").text            
126. res3: String =
127. Viale delle Terme di Caracalla
128.        Rome00153Italyjippe.hoogeveen@fao.org
129.       
130. // print all character string text one per line
131. scala> (address \\ "CharacterString").map( _.text ).mkString("\n")
132. res6: String =
133. Viale delle Terme di Caracalla
134.       
135. Rome
137. 00153
138. Italy
139. jippe.hoogeveen@fao.org
141. // find the longest character string
142. scala> (address \\ "CharacterString").reduceRight(  
143.      | (elem, longest) => {
144.      | if( elem.text.length > longest.text.length ) elem
145.      | else longest
146.      | })
147. res8: scala.xml.Node =
148. <CharacterString>Viale delle Terme di Caracalla
149.        </CharacterString>
152. // find the alphabetically first characterstring
153. scala> (address \\ "CharacterString").reduceRight( (elem, longest) => {
154.      | if( elem.text > longest.text ) elem
155.      | else longest
156.      | })
157. res9: scala.xml.Node =
158. <CharacterString>jippe.hoogeveen@fao.org
159.        </CharacterString>