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From "Oliver Heger (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CONFIGURATION-677) FileBasedConfigurationBuilder allowFailOnInit vs HomeDirectoryLocationStrategy
Date Sat, 02 Dec 2017 20:15:00 GMT

    [ https://issues.apache.org/jira/browse/CONFIGURATION-677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16275730#comment-16275730
] 

Oliver Heger commented on CONFIGURATION-677:
--------------------------------------------

Thanks for this report.

I agree that based on the documentation a user may expect too much. The ideal solution in
your case would probably be that the configuration file was created correctly in the user's
home directory. With the current interfaces of location strategies this cannot be achieved,
however. HomeDirectoryLocationStrategy can only find out that the requested file does not
exist, but there is no way for it to give a hint upstream where the file should be stored
once it has been created. (With multiple location strategies in place, there would probably
be no clear solution which one should define the target location.)

So an update of documentation would be appropriate. The feature of optional configuration
sources was originally intended to be used together with {{CombinedConfigurationBuilder}}.
Here optional sources can be included, and by using interpolation with system properties the
target path can be specified exactly. I will try to improve the documentation in this area.

> FileBasedConfigurationBuilder allowFailOnInit vs HomeDirectoryLocationStrategy
> ------------------------------------------------------------------------------
>
>                 Key: CONFIGURATION-677
>                 URL: https://issues.apache.org/jira/browse/CONFIGURATION-677
>             Project: Commons Configuration
>          Issue Type: Bug
>          Components: Documentation, File reloading
>    Affects Versions: 2.2
>         Environment: macOS Sierra 10.12.6, Java 1.8.0_152
>            Reporter: Piotr Skowronek
>             Fix For: 2.x
>
>
> It seems there's a problem with configuration creation when using FileBasedConfigurationBuilder
with allowFailOnInit together with HomeDirectoryLocationStrategy and autoSave option.
> If the configuration is present in user.home directory (let's say ~/.some.config) it
is being loaded and updated properly, but if the file does *not exist* then the configuration
is created in current working directory (where the java program was launched) and *not* in
user home directory.
> Javadoc of BasicConfigurationBuilder states as follow:
> {quote}A builder instance can be constructed with an <em>allowFailOnInit</em>
>  * flag. If set to <strong>true</strong>, exceptions during initialization
>  * of the configuration are ignored; in such a case an empty configuration
>  * object is returned. A use case for this flag is a scenario in which a
>  * configuration is optional and created on demand the first time configuration
>  * data is to be stored. Consider an application that stores user-specific
>  * configuration data in the user's home directory: When started for the first
>  * time by a new user there is no configuration file; so it makes sense to
>  * start with an empty configuration object. On application exit, settings
>  * can be stored in this object and written to the associated file. Then they
>  * are available on next application start.
> {quote}
> So, either it is a bug and it should be fixed in the Configuration project or it is the
correct behavior and it is the programmer to ensure to write the configuration in the right
place for the first time. If the latter then I would suggest to update javadoc to state that
clearly enough (and maybe provide an example on the project website).
> Code sample:
> {code}
>         // file not present: ~/.some.config
>         BuilderParameters params = new Parameters().properties().setFileName(".some.config")
>             .setLocationStrategy(new HomeDirectoryLocationStrategy());
>         builder = new FileBasedConfigurationBuilder<FileBasedConfiguration>(PropertiesConfiguration.class,
params.getParameters(), true);
>         builder.setAutoSave(true);
>         config = builder.getConfiguration();
>         config.setProperty("test", "test);
>         // config file .some.config not present in ~/.some.config but present in CWD
> {code}



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