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Show Commands

One of the most common patterns with command line programs is the need to print properties of objects. cliff provides a base class for commands of this type so that they only need to prepare the data, and the user can choose from one of several output formatter plugins to see the data in their preferred format.

ShowOne

The cliff.show.ShowOne base class API extends Command to allow take_action to return data to be formatted using a user-selectable formatter. Subclasses should provide a take_action implementation that returns a two member tuple containing a tuple with the names of the columns in the dataset and an iterable that contains the data values associated with those names. See the description of the file command in the demoapp <demoapp-show> for details.

Show Output Formatters

cliff is delivered with output formatters for show commands. ShowOne adds a command line switch to let the user specify the formatter they want, so you don't have to do any extra work in your application.

html

The html formatter uses tablib to produce HTML output as a table.

(.venv)$ cliffdemo file -f html setup.py
<table>
<thead>
<tr><th>Field</th>
<th>Value</th></tr>
</thead>
<tr><td>Name</td>
<td>setup.py</td></tr>
<tr><td>Size</td>
<td>6373</td></tr>
<tr><td>UID</td>
<td>527</td></tr>
<tr><td>GID</td>
<td>501</td></tr>
<tr><td>Modified Time</td>
<td>1336353173.0</td></tr>
</table>

json

The json formatter uses tablib to produce JSON output.

(.venv)$ cliffdemo file -f json setup.py
[{"Field": "Name", "Value": "setup.py"}, {"Field": "Size",
"Value": 6373}, {"Field": "UID", "Value": 527}, {"Field": "GID",
"Value": 501}, {"Field": "Modified Time", "Value": 1336353173.0}]

shell

The shell formatter produces output that can be parsed directly by a typical UNIX shell as variable assignments. This avoids extra parsing overhead in shell scripts.

(.venv)$ cliffdemo file -f shell setup.py
name="setup.py"
size="5916"
uid="527"
gid="501"
modified_time="1335655655.0"

(.venv)$ eval "$(cliffdemo file -f shell --prefix example_ setup.py)"
(.venv)$ echo $example_size
5916

table

The table formatter uses PrettyTable to produce output formatted for human consumption.

(.venv)$ cliffdemo file setup.py
+---------------+--------------+
|     Field     |    Value     |
+---------------+--------------+
| Name          | setup.py     |
| Size          | 5825         |
| UID           | 502          |
| GID           | 20           |
| Modified Time | 1335569964.0 |
+---------------+--------------+

yaml

The yaml formatter uses tablib to produce YAML output as a sequence of mappings.

(.venv)$ cliffdemo file -f yaml setup.py
- {Field: Name, Value: setup.py}
- {Field: Size, Value: 6373}
- {Field: UID, Value: 527}
- {Field: GID, Value: 501}
- {Field: Modified Time, Value: 1336353173.0}

Creating Your Own Formatter

If the standard formatters do not meet your needs, you can bundle another formatter with your program by subclassing from cliff.formatters.base.ShowFormatter and registering the plugin in the cliff.formatter.show namespace.

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