Clojure XML 解析
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Clojure XML Parsing
提问by Hamza Yerlikaya
I can not find any info on how to parse xml documents and access elements.
我找不到有关如何解析 xml 文档和访问元素的任何信息。
I have found two ways to parse the xml document
我找到了两种解析xml文档的方法
(clojure.zip/xml-zip (clojure.xml/parse file))
and
和
(parse-seq file)
but i can seem to find any info on how to process the resulting structure?
但我似乎可以找到有关如何处理结果结构的任何信息？
Source file's refers to zip-query.clj on how to query the result but that seems to missing too.
源文件是指关于如何查询结果的 zip-query.clj，但这似乎也缺失了。
回答by Pinochle
Suppose you have the following xml to parse in your file:
假设您的文件中有以下 xml 需要解析：
<high-node>
<low-node>my text</low-node>
</high-node>
you load clojure.xml:
你加载clojure.xml：
user=> (use 'clojure.xml)
when parsed, the xml will have the following structure:
解析后，xml 将具有以下结构：
{:tag :high-node, :attrs nil, :content [{:tag :low-node, :attrs nil, :content ["my text"]}]}
and then you can seq over the content of the file to get the content of the low-node:
然后您可以对文件的内容进行 seq 以获取以下内容low-node：
user=> (for [x (xml-seq
(parse (java.io.File. file)))
:when (= :low-node (:tag x))]
(first (:content x)))
("my text")
Similarly, if you wanted to have access to the entire list of information on low-node, you would change the :whenpredicate to (= (:high-node (:tag x))):
同样，如果您想访问低节点上的整个信息列表，您可以将:when谓词更改为(= (:high-node (:tag x)))：
user=> (for [x (xml-seq
(parse (java.io.File. file)))
:when (= :high-node (:tag x))]
(first (:content x)))
({:tag :low-node, :attrs nil, :content ["my text"]})
This works because the keywords can operate as functions. See Questions about lists and other stuff in Clojureand Data Structures: Keywords
这是有效的，因为关键字可以作为函数运行。请参阅有关 Clojure和数据结构中的列表和其他内容的问题：关键字
回答by overthink
The above answer works, but I find it a lot easier to use clojure.data.zip.xml(used to be clojure-contrib.zip-filter.xmlprior to Clojure 1.3).
上面的答案有效，但我发现它更容易使用clojure.data.zip.xml（曾经clojure-contrib.zip-filter.xml在 Clojure 1.3 之前）。
file:
文件：
myfile.xml:
myfile.xml：
<songs>
<track id="t1"><name>Track one</name></track>
<track id="t2"><name>Track two</name></track>
</songs>
code:
代码：
; Clojure 1.3
(ns example
(:use [clojure.data.zip.xml :only (attr text xml->)]) ; dep: see below
(:require [clojure.xml :as xml]
[clojure.zip :as zip]))
(def xml (xml/parse "myfile.xml"))
(def zipped (zip/xml-zip xml))
(xml-> zipped :track :name text) ; ("Track one" "Track two")
(xml-> zipped :track (attr :id)) ; ("t1" "t2")
Unfortunately, you need to pull in a dependency on data.zipto get this nice read/filter functionality. It's worth the dependency :)In leinit would be (as of 17-Aug-2013):
不幸的是，您需要依赖于data.zip才能获得这个不错的读取/过滤功能。 值得依赖:)在lein中（截至 2013 年 8 月 17 日）：
[org.clojure/data.zip "0.1.1"]
And as for docs for data.zip.xml... I just look at the relatively small source file hereto see what is possible. Another good SO answer here, too.
至于文档data.zip.xml...我只是看看这里相对较小的源文件，看看有什么可能。这里也是另一个很好的 SO 答案。
