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<H2><A NAME="SECTION0082960000000000000000">
6.29.6 Formatter Objects</A>
</H2>

<P>
<tt class="class">Formatter</tt>s have the following attributes and methods. They are
responsible for converting a <tt class="class">LogRecord</tt> to (usually) a string
which can be interpreted by either a human or an external system. The
base
<tt class="class">Formatter</tt> allows a formatting string to be specified. If none is
supplied, the default value of <code>'%(message)s'</code> is used.

<P>
A Formatter can be initialized with a format string which makes use of
knowledge of the <tt class="class">LogRecord</tt> attributes - such as the default value
mentioned above making use of the fact that the user's message and
arguments are pre-formatted into a <tt class="class">LogRecord</tt>'s <var>message</var>
attribute.  This format string contains standard python %-style
mapping keys. See section <A href="typesseq-strings.html#typesseq-strings">2.3.6</A>, ``String Formatting
Operations,'' for more information on string formatting.

<P>
Currently, the useful mapping keys in a <tt class="class">LogRecord</tt> are:

<P>
<div class="center"><table class="realtable">
  <thead>
    <tr>
      <th class="left"  >Format</th>
      <th class="left"  >Description</th>
      </tr>
    </thead>
  <tbody>
    <tr><td class="left"   valign="baseline"><code>%(name)s</code></td>
        <td class="left"  >Name of the logger (logging channel).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(levelno)s</code></td>
        <td class="left"  >Numeric logging level for the message
                        (<tt class="constant">DEBUG</tt>, <tt class="constant">INFO</tt>,
                        <tt class="constant">WARNING</tt>, <tt class="constant">ERROR</tt>,
                        <tt class="constant">CRITICAL</tt>).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(levelname)s</code></td>
        <td class="left"  >Text logging level for the message
                        (<code>'DEBUG'</code>, <code>'INFO'</code>,
                        <code>'WARNING'</code>, <code>'ERROR'</code>,
                        <code>'CRITICAL'</code>).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(pathname)s</code></td>
        <td class="left"  >Full pathname of the source file where the logging
                        call was issued (if available).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(filename)s</code></td>
        <td class="left"  >Filename portion of pathname.</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(module)s</code></td>
        <td class="left"  >Module (name portion of filename).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(lineno)d</code></td>
        <td class="left"  >Source line number where the logging call was issued
                        (if available).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(created)f</code></td>
        <td class="left"  >Time when the <tt class="class">LogRecord</tt> was created (as
                        returned by <tt class="function">time.time()</tt>).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(asctime)s</code></td>
        <td class="left"  >Human-readable time when the <tt class="class">LogRecord</tt>
                        was created.  By default this is of the form
                        ``2003-07-08 16:49:45,896'' (the numbers after the
                        comma are millisecond portion of the time).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(msecs)d</code></td>
        <td class="left"  >Millisecond portion of the time when the
                        <tt class="class">LogRecord</tt> was created.</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(thread)d</code></td>
        <td class="left"  >Thread ID (if available).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(threadName)s</code></td>
        <td class="left"  >Thread name (if available).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(process)d</code></td>
        <td class="left"  >Process ID (if available).</td></tr>
    <tr><td class="left"   valign="baseline"><code>%(message)s</code></td>
        <td class="left"  >The logged message, computed as <code>msg % args</code>.</td></tr></tbody>
</table></div>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><span class="typelabel">class</span>&nbsp;<tt id='l2h-2555' xml:id='l2h-2555' class="class">Formatter</tt></b>(</nobr></td>
  <td><var></var><big>[</big><var>fmt</var><big>[</big><var>, datefmt</var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Returns a new instance of the <tt class="class">Formatter</tt> class. The
instance is initialized with a format string for the message as a whole,
as well as a format string for the date/time portion of a message. If
no <var>fmt</var> is specified, <code>'%(message)s'</code> is used. If no <var>datefmt</var>
is specified, the ISO8601 date format is used.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2556' xml:id='l2h-2556' class="method">format</tt></b>(</nobr></td>
  <td><var>record</var>)</td></tr></table></dt>
<dd>
The record's attribute dictionary is used as the operand to a
string formatting operation. Returns the resulting string.
Before formatting the dictionary, a couple of preparatory steps
are carried out. The <var>message</var> attribute of the record is computed
using <var>msg</var> % <var>args</var>. If the formatting string contains
<code>'(asctime)'</code>, <tt class="method">formatTime()</tt> is called to format the
event time. If there is exception information, it is formatted using
<tt class="method">formatException()</tt> and appended to the message.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2557' xml:id='l2h-2557' class="method">formatTime</tt></b>(</nobr></td>
  <td><var>record</var><big>[</big><var>, datefmt</var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
This method should be called from <tt class="method">format()</tt> by a formatter which
wants to make use of a formatted time. This method can be overridden
in formatters to provide for any specific requirement, but the
basic behavior is as follows: if <var>datefmt</var> (a string) is specified,
it is used with <tt class="function">time.strftime()</tt> to format the creation time of the
record. Otherwise, the ISO8601 format is used. The resulting
string is returned.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2558' xml:id='l2h-2558' class="method">formatException</tt></b>(</nobr></td>
  <td><var>exc_info</var>)</td></tr></table></dt>
<dd>
Formats the specified exception information (a standard exception tuple
as returned by <tt class="function">sys.exc_info()</tt>) as a string. This default
implementation just uses <tt class="function">traceback.print_exception()</tt>.
The resulting string is returned.
</dl>

<P>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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