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Custom export filters

JabRef allows you to define and use your own export filters, in the same way as the standard export filters are defined. An export filter is defined by one or more layout files, which with the help of a collection of built-in formatter routines specify the format of the exported files. Your layout files must be prepared in a text editor outside of JabRef.

Adding a custom export filter

The only requirement for a valid export filter is the existence of a file with the extension .layout. To add a new custom export filter, open the dialog box Options -> Manage custom exports, and click Add new. A new dialog box will appear, allowing you to specify a name for the export filter (which will appear as one of the choices in the File type dropdown menu of the file dialog when you use the File -> Export menu choice in the JabRef window), the path to the .layout file, and the preferred file extension for the export filter (which will be the suggested extension in the file dialog when you use the export filter).

Creating the export filter

To see examples of how export filters are made, look for the package containing the layout files for the standard export filters on our download page.

Layout files

Let us assume that we are creating an HTML export filter.

While the export filter only needs to consist of a single .layout file, which in this case could be called html.layout, you may also want to add two files called html.begin.layout and html.end.layout. The former contains the header part of the output, and the latter the footer part. JabRef will look for these two files whenever the export filter is used, and if found, either of these will be copied verbatim to the output before or after the individual entries are written.

Note that these files must reside in the same directory as html.layout, and must be named by inserting .begin and .end, respectively.

In our example export filter, these could look like the following:

html.begin.layout:
<HTML>
<BODY> text="#275856">
<basefont size="4" color="#2F4958" face="arial">

html.end.layout:
</BODY>
</HTML>

The file html.layout provides the default template for exporting one single entry. If you want to use different templates for different entry types, you can do this by adding entry-specific .layout files. These must also reside in the same directory as the main layout file, and are named by inserting .entrytype into the name of the main layout file. The entry type name must be in all lowercase. In our example, we might want to add a template for book entries, and this would go into the file html.book.layout. For a PhD thesis we would add the file html.phdthesis.layout, and so on. These files are similar to the default layout file, except that they will only be used for entries of the matching type. Note that the default file can easily be made general enough to cover most entry types in most export filters.

The layout file format

Layout files are created using a simple markup format where commands are identified by a preceding backslash. All text not identified as part of a command will be copied verbatim to the output file.

Field commands

An arbitrary word preceded by a backslash, e.g. \author, \editor, \title or \year, will be interpreted as a reference to the corresponding field, which will be copied directly to the output.

Field formatters

Often there will be a need for some preprocessing of the field contents before output. This is done using a field formatter - a java class containing a single method that manipulates the contents of a field.

A formatter is used by inserting the \format command followed by the formatter name in square braces, and the field command in curly braces, e.g.:

\format[ToLowerCase]{\author}

You can also specify multiple formatters separated by commas. These will be called sequentially, from left to right, e.g.

\format[ToLowerCase,HTMLChars]{\author}

will cause the formatter ToLowerCase to be called first, and then HTMLChars will be called to format the result. You can list an arbitrary number of formatters in this way.

The argument to the formatters, withing the curly braces, does not have to be a field command. Instead, you can insert normal text, which will then be passed to the formatters instead of the contents of any field. This can be useful for some fomatters, e.g. the CurrentDate formatter (described below).

JabRef provides the following set of formatters, some of which depend on the others:

If none of the available formatters can do what you want to achieve, you can add your own by implementing the net.sf.jabref.export.layout.LayoutFormatter interface. If you insert your class into the net.sf.jabref.export.layout.format package, you can call the formatter by its class name only, like with the standard formatters. Otherwise, you must call the formatter by its fully qualified name (including package name). In any case, the formatter must be in your classpath when running JabRef.

Using Custom Name Formatters

With JabRef 2.2 it is now possible to define custom name formatters using the bibtex-sty-file syntax. This allows ultimate flexibility, but is a cumbersome to write

You can define your own formatter in the preference tab "Name Formatter" using the following format and then use it with the name given to it as any other formatter

<case1>@<range11>@<format>@<range12>@<format>@<range13>...@@
<case2>@<range21>@... and so on.

This format first splits the task to format a list of author into cases depending on how many authors there are (this is since some formats differ depending on how many authors there are). Each individual case is separated by @@ and contains instructions on how to format each author in the case. These instructions are separated by a @.

Cases are identified using integers (1, 2, 3, etc.) or the character * (matches any number of authors) and will tell the formatter to apply the following instructions if there are a number of less or equal of authors given.

Ranges are either <integer>..<integer>, <integer> or the character * using a 1 based index for indexing authors from the given list of authors. Integer indexes can be negative to denote them to start from the end of the list where -1 is the last author.

For instance with an authorlist of "Joe Doe and Mary Jane and Bruce Bar and Arthur Kay":

The <format>-strings use the Bibtex formatter format:

The four letters v, f, l, j indicate the name parts von, first, last, jr which are used within curly braces. A single letter v, f, l, j indicates that the name should be abbreviated. If one of these letters or letter pairs is encountered JabRef will output all the respective names (possibly abbreviated), but the whole expression in curly braces is only printed if the name part exists.

For instance if the format is "{ll} {vv {von Part}} {ff}" and the names are "Mary Kay and John von Neumann", then JabRef will output "Kay Mary" (with two space between last and first) and "Neuman von von Part John".

I give two examples but would rather point you to the bibtex documentation.

Small example: "{ll}, {f.}" will turn "Joe Doe" into "Doe, J."

Large example:

To turn:

"Joe Doe and Mary Jane and Bruce Bar and Arthur Kay"

into

"Doe, J., Jane, M., Bar, B. and Kay, A."

you would use

1@*@{ll}, {f}.@@2@1@{ll}, {f}.@2@ and {ll}, {f}.@@*@1..-3@{ll}, {f}., @-2@{ll}, {f}.@-1@ and {ll}, {f}.

If somebody would like to write a better tutorial about this: Write a mail to one of the JabRef mailinglists!

Conditional output

Some static output might only make sense if a specific field is set. For instance, say we want to follow the editor names with the text (Ed.). This can be done with the following text:

\format[HTMLChars,AuthorFirstFirst]{\editor} (Ed.)

However, if the editor field has not been set - it might not even make sense for the entry being exported - the (Ed.) would be left hanging. This can be prevented by instead using the \begin and \end commands:

\begin{editor}
\format[HTMLChars,AuthorFirstFirst]{\editor} (Ed.)
\end{editor}

The \begin and \end commands make sure the text in between is printed if and only if the field referred in the curly braces is defined for the ently being exported.

Note: Use of the \begin and \end commands is a key to creating layout files that work well with a variety of entry types.

Grouped output

If you wish to separate your entries into groups based on a certain field, use the grouped output commands. Grouped output is very similar to conditional output, except that the text in between is printed only if the field referred in the curly braces has changed value.

For example, let's assume I wish to group by keyword. Before exporting the file, make sure you have sorted your entries based on keyword. Now use the following commands to group by keyword:

\begingroup{keywords}New Category: \format[HTMLChars]{\keywords}
\endgroup{keywords}

Sharing your work

With external layout files, it's fairly simple to share custom export formats between users. If you write an export filter for a format not supported by JabRef, or an improvement over an existing one, we encourage you to post your work on our SourceForge.net page. The same goes for formatter classes that you write. We'd be happy to distribute a collection of submitted layout files, or to add to the selection of standard export filters and formatters.