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1 {{box cssClass="floatinginfobox" title="**Contents**"}}
2 {{toc/}}
3 {{/box}}
4
5 There are times when you wish to save data. The XWiki platform offers various places that you can use depending on your needs. Here's a rundown of all the options you have.
6
7 = Transient Saves =
8
9 == Execution Context ==
10
11 If the data to be saved should only be saved for the duration of a Request (i.e. a call to a XWiki URL), then you should use the **Execution Context**.
12
13 For example, from Java in a Component:
14
15 {{code language="java"}}
16 import org.xwiki.execution.*;
17
18 @Inject Execution execution;
19 ...
20 // Saving
21 ExecutionContext ec = execution.getContext();
22 ec.setProperty("mykey", myvalue);
23 ...
24 // Retrieving
25 Object myvalue = e.getProperty("mykey");
26 {{/code}}
27
28 From a wiki page (Note that [[we currently cannot access easily the Execution Context from a wiki page but this should be improved>>http://jira.xwiki.org/browse/XCOMMONS-242]] and currently it's not available only from Velocity but it is from Groovy for example):
29
30 {{code}}
31 {{groovy}}
32 import org.xwiki.context.*
33
34 def ec = services.component.getInstance(Execution.class).getContext()
35 ec.setProperty("mykey", myvalue)
36 {{/groovy}}
37 {{/code}}
38
39 Note that from a wiki page it's much easier to use the older **XWiki Context** (which is supposed to be fully replaced by the Execution Context at some point in the future). For example:
40
41 {{code}}
42 {{velocity}}
43 $xcontext.put("mykey", value)
44 {{/velocity}}
45 {{/code}}
46
47 == Servlet Session ==
48
49 If the data should last a little longer (i.e. for example span more than 1 request), you could save it in the Servlet Session.
50
51 For example, from Java in a Component:
52
53 {{code language="java"}}
54 import org.xwiki.container.*;
55
56 @Inject Container container;
57 ...
58 Request request = container.getRequest();
59 // Note that this is a bit of a hack and the notion of Session exists in the Container class (getSession()) but the Session interface is empty at the moment, making it useless)
60 if (request instanceof ServletRequest) {
61 HttpServletRequest servletRequest = (ServletRequest) request;
62 HttpSession session = servletRequest.getSession();
63 session.setAttribute("mykey", myvalue);
64 }
65 {{/code}}
66
67 == Temporary Directory ==
68
69 If the data should last even a little longer than a session, you could save it in a File in the Environment's Temporary Directory.
70
71 For example, from Java in a Component:
72
73 {{code language="java"}}
74 import org.xwiki.environment.*;
75 import org.apache.commons.io.*;
76
77 @Inject Environment environment;
78 ...
79 File tmpDir = environment.getTemporaryDirectory();
80 FileUtils.write(tmpDir, "something");
81 {{/code}}
82
83 == Servlet Context ==
84
85 If the Data should last as long as the web application is up, you could use the Servlet Context. It's not very easy to access it but it's possible.
86
87 For example, from Java in a Component:
88
89 {{code language="java"}}
90 import org.xwiki.container.*;
91 import com.xpn.xwiki.*;
92 import com.xpn.xwiki.web.*;
93
94 @Inject Execution execution;
95 ...
96 // Get the older XWiki Context
97 XWikiContext xc = (XWikiContext) execution.getContext().getProperty("xwikicontext");
98 XWikiEngineContext ec = xc.getEngineContext();
99 ec.setAttribute("mykey", myvalue);
100 {{/code}}
101
102 = Permanent Saves =
103
104 == Wiki Model ==
105
106 The best place to save Data is usually in the wiki itself (See the [[Data Model>>DevGuide.DataModel]] and the [[API Guide for some examples>>DevGuide.APIGuide]]). There are several places where you can store data in the model:
107 * In the Document content itself,
108 * In an XObject attached to a Document,
109 * In an Attachment
110
111 == Permanent Directory ==
112
113 Another possibility is to use the Environment's Permanent Directory.
114
115 For example, from Java in a Component:
116
117 {{code language="java"}}
118 import org.xwiki.environment.*;
119 import org.apache.commons.io.*;
120
121 @Inject Environment environment;
122 ...
123 File permDir = environment.getPermanentDirectory();
124 FileUtils.write(permDir, "something");
125 {{/code}}

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