Printing Blog Posts

I like printing blog posts and reading them later, but too many blogs don’t provide functionality to print well formatted posts. I end up printing sidebars, advertisements and other clutter along with the post, thanks to lousy print formatting in browsers. What a waste !

It is actually quite easy to add a “Print This Post” button to a WordPress blog. One great option (the one I use on this blog) is WP-Print. Make sure you read Installation and Usage instructions. Brilliant job !

Another option is HP Blog Printing. This works with some other blogging platforms also. I like the simplicity of WP-Print more than the feature set of HP plugin. HP also requires you to sign up.

How do you format posts for printing, when a blog doesn’t have such feature ?

Leveraging XPATH Axes

XPATH axes come in very handy when nodes need to be selected based on (attribute’s or child element’s) values that must match those of other nodes elsewhere in the xml tree. Consider the following log4net configuration file :


<?xml version="1.0"?>

<configuration>
    <configSections>
        <section name="nhibernate"
            type="System.Configuration.NameValueSectionHandler, System,
            Version=2.0.0.0,Culture=neutral, PublicKeyToken=b77a5c561934e089" />
        <section name="log4net"
            type="log4net.Config.Log4NetConfigurationSectionHandler,log4net" />
    </configSections>
    <nhibernate>
        <add key="hibernate.connection.provider"
            value="NHibernate.Connection.DriverConnectionProvider" />
        <add key="hibernate.connection.driver_class"
            value="NHibernate.Driver.SqlClientDriver" />
        <add key="hibernate.connection.connection_string"
            value="Server=servername; Database=dbname;
            User=username; Password=secret;" />
        <add key="hibernate.connection.isolation" value="ReadCommitted" />
        <add key="hibernate.dialect"
            value="NHibernate.Dialect.MsSql2000Dialect" />
    </nhibernate>

    <log4net>
        <appender name="NHibernateFileLog"
        type="log4net.Appender.RollingFileAppender">
            <file value="Logs/nhibernate.txt" />
            <appendToFile value="true" />
            <rollingStyle value="Size" />
            <maxSizeRollBackups value="10" />
            <maximumFileSize value="100KB" />
            <staticLogFileName value="true" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern
                value="%d{HH:mm:ss.fff} [%t] %-5p %c - %m%n"  />
            </layout>
        </appender>

        <appender name="GeneralLog"
            type="log4net.Appender.RollingFileAppender">
            <file value="Logs/general.txt" />
            <appendToFile value="true" />
            <maximumFileSize value="100KB" />
            <rollingStyle value="Size" />
            <maxSizeRollBackups value="5" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern
                value="%d{HH:mm:ss.fff} [%t] %-5p %c - %m%n"  />
            </layout>
        </appender>
        <appender name="DataLog"
            type="log4net.Appender.RollingFileAppender">
            <file value="Logs/data.txt" />
            <appendToFile value="true" />
            <maximumFileSize value="100KB" />
            <rollingStyle value="Size" />
            <maxSizeRollBackups value="5" />
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern
                value="%d{HH:mm:ss.fff} [%t] %-5p %c - %m%n"  />
            </layout>
        </appender>

        <!-- levels: DEBUG, INFO, WARN, ERROR, FATAL -->

        <root>
            <level value="DEBUG"/>
            <appender-ref ref="GeneralLog" />
        </root>

        <logger name="NHibernate" additivity="false">
            <level value="DEBUG"/>
            <appender-ref ref="NHibernateFileLog"/>
        </logger>
        <logger name="Pushable.Data" additivity="false">
            <level value="DEBUG"/>
            <appender-ref ref="DataLog"/>
        </logger>
    </log4net>
</configuration>


The <appender>s are referenced by <logger>s using ‘ref’ attribute of their ‘appender-ref’ child elements, using the same value as the ‘name’ attribute of the <appender>. This type of linking is quite common in xml documents. Now, The first question is : How to list files that are referenced by <logger>s ?
In order to solve this problem you will need to reach the <appender>s that are referenced by each <logger> and then extract the ‘value’ of their <file>s.


Solution:

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">

    <xsl:output method="text"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="log4net">
        <xsl:apply-templates
            select="appender[@name=parent::log4net/logger/appender-ref/@ref]"/>
    </xsl:template>

    <xsl:template match="appender">
        <xsl:value-of
            select="file/@value"/> <xsl:text>&#10;</xsl:text>
    </xsl:template>

</xsl:stylesheet>


The second question is : How to write an xslt script to transform this xml document into an html document with a table that looks like this –

NHibernate Logs/nhibernate.txt
Pushable.Data Logs/data.txt

Solution:

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="1.0">

    <xsl:output method="html"/>

    <xsl:template match="log4net">
        <HTML>
            <HEAD>
                <TITLE>www.tewari.info : using xpath axes</TITLE>
            </HEAD>
            <BODY>
                <TABLE border="1" width="25%">
                    <TR><TH>Logger</TH><TH>File</TH></TR>
                    <xsl:apply-templates select="logger"/>
                </TABLE>
            </BODY>
        </HTML>
    </xsl:template>

    <xsl:template match="logger">
            <xsl:variable name="aName" select="appender-ref/@ref"/>
            <TR>
            <TD><xsl:value-of select="@name"/></TD>
            <TD><xsl:value-of
                select="parent::log4net/appender[@name=$aName]/file/@value"/></TD>
            </TR>
    </xsl:template>

</xsl:stylesheet>


Credits :

  • SketchPath is a brilliant tool to play with xpath. I love the “New Context” button : Click on a node and hit “New Context” to change the context for the xpath query processor !