Data Sources
Contents or URLs can be searched for using the <contents>,
<templates> or <media> tags, which allow
you to search a data source (directory, delimiter-separated-values file,
database etc.) for a pattern.
Currently two data source protocols are defined, file: and svfile: .
Attributes Supported By Datasource Tags
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src
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All datasources require this attribute, which
specifies a protocol and path, in a URL-style syntax:
protocol:path . file: is the default protocol, if none is
specified.
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name
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This attribute is used to specify the pattern of data,
under this path, which will be converted into content items. The part
of the data's location which matches this name pattern will become the
name of the item. Typically, WebMake glob patterns, such as
"*.txt" or ".../*.html" are used.
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prefix
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The items' names can be further modified by specifying
a prefix and/or suffix; these strings are prepended or
appended to the raw name to make the name the content is given.
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suffix
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See above.
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namesubst
-
a Perl-formatted s// substitution, which is used to
convert source filenames to content names. See the example under
The File: Protocol, below.
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nametr
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a Perl tr// translation, which is used to convert
source filenames to content names.
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listname
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a name of a content item. This content item will be
created, and will contain the names of all content items picked up by
the <contents> or <media> search.
In addition, the attributes supported by the content tag can
be specified as attributes to <contents>, including
format, up, map, etc.
The content blocks picked up from a <contents> search can
also contain meta-data, such as headlines, visibilty dates, workflow approval
statuses, etc. by including metadata.
The file: Protocol
The file: protocol loads content from a directory; each file is made into one
content chunk. The src attribute indicates the source directory, the
name attribute indicates the glob pattern that will pick up the
content items in question.
<contents src="stories" name="*.txt" />
The filename of the file will be used as the content chunk's name -- unless
you use the namesubst command; see below for details on this.
Note that, for efficiency, the files in question are not actually opened until
their content chunks are referenced using ${name} or
get_content("name").
Searching Recursively Through A Directory Tree
Normally only the top level of files inside the src directory are added to
the content set. However, if the name pattern starts with .../, the
directory will be searched recursively:
<contents src="stories" name=".../*.txt" />
The resulting content items will contain the full path from that directory
down, i.e. the file stories/dir1/foo/bar.txt exists, the example above
would define a content item called ${dir1/foo/bar.txt}.
The namesubst Option
If you use the namesubst command, the filename will be modified using that
substitution, to give the content item's name. So, for example, this contents
tag:
<contents src="stories" name="*.txt" namesubst="s/.txt//" />
will load these example files as follows:
Filename
|
Content Name
|
stories/index.txt
|
${index}
|
stories/foo.txt
|
${foo}
|
stories/directory/bar.txt
|
${directory/bar}
|
stories/zz/gum/baz.txt
|
${zz/gum/baz}
|
The svfile: Protocol
The svfile: protocol loads content from a delimiter-separated-file; the
src attribute is the name of the file, the name is the glob
pattern used to catch the relevant content items. The namefield
attribute specifies the field number (counting from 1) which the name
pattern is matched against, and the valuefield specifies the number of
the field from which the content chunk is read. The delimiter
attribute specifies the delimiter used to separate values in the file.
<contents src="svfile:stories.csv" name="*"
namefield=1 valuefield=2 delimiter="," />
Adding New Protocols
New data sources for <contents> and <media> tags are added by
writing an implementation of the DataSourceBase.pm module, in the
HTML::WebMake::DataSources package space (the
lib/HTML/WebMake/DataSources directory of the distribution).
Every data source needs a protocol, an alphanumeric lowercase identifier
to use at the start of the src attribute to indicate that a data source is
of that type.
Each implementation of this module should implement these methods:
-
new ($parent)
-
instantiate the object, as usual.
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add ()
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add all the items in that data source as content
chunks. (See below!)
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get_location_url ($location)
-
get the location (in URL
format) of a content chunk loaded by add() .
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get_location_contents ($location)
-
get the contents of the
location. The location, again, is the string provided by add() .
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get_location_mod_time ($location)
-
get the current modification
date of a location for dependency checking. The location, again, is
in the format of the string provided by add() .
Notes:
-
If you want add() to read the content immediately, call
$self->{parent}->add_text ($name, $text, $self->{src},
$modtime) .
-
add() can defer opening and reading content chunks straight away.
If it calls $self->{parent}->add_location ($name, $location,
$lastmod) , providing a location string which starts with the data
source's protocol identifier, the content will not be loaded until
it is needed, at which point get_location_contents() is called.
-
This location string should contain all the information needed to
access that content chunk later, even if add() was not been
called. Consider it as similar to a URL. This is required so that
get_location_mod_time() (see below) can work.
-
All implementations of add() should call $fixed =
$self->{parent}->fixname ($name); to modify the name of each
content chunk appropriately, followed by
$self->{parent}->add_file_to_list ($fixed); to add the content
chunk's name to the filelist content item.
-
Data sources that support the <media> tag need to implement
get_location_url , otherwise an error message will be output.
-
Data sources that support the <contents> tag, and defer
reading the content until it's required, need to implement
get_location_contents , which is used to provide content from a
location set using $self->{parent}->add_location() .
-
Data sources that support the <contents> tag need to implement
get_location_mod_time . This is used to support dependency
checking, and should return the modification time (in UNIX
time_t format) of that location. Note that since this is used
to compare the modification time of a content chunk from the
previous time webmake was run, and the current modification time,
this is called before the real data source is opened.
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