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124 changes: 124 additions & 0 deletions components/console/helpers/debug_formatter.rst
Original file line number Diff line number Diff line change
@@ -0,0 +1,124 @@
.. index::
single: Console Helpers; DebugFormatter Helper

Debug Formatter Helper
======================

.. versionadded:: 2.6
The Debug Formatter helper was introduced in Symfony 2.6.

The :class:`Symfony\\Component\\Console\\Helper\\DebugFormatterHelper` provides
functions to output debug information when running an external program, for
instance a process or HTTP request. It is included in the default helper set
and you can get it by calling
:method:`Symfony\\Component\\Console\\Command\\Command::getHelper`::

$debugFormatter = $this->getHelper('debug_formatter');
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The example is a bit confusing since you talk about getHelperSet(), but actually use getHelper().


The formatter only formats strings, which you can use to output to the console,
but also to log the information or do anything else.

All methods of this helper have an identifier as the first argument. This is a
unique value for each program. This way, the helper can debug information for
multiple programs at the same time. When using the
:doc:`Process component </components/process>`, you probably want to use
:phpfunction:`spl_object_hash`.

.. tip::

This information is often too verbose to be shown by default. You can use
:ref:`verbosity levels <verbosity-levels>` to only show it when in
debugging mode (``-vvv``).

Starting a Program
------------------

As soon as you start a program, you can use
:method:`Symfony\\Component\\Console\\Helper\\DebugFormatterHelper::start` to
display information that the program is started::

// ...
$process = new Process(...);
$process->run();

$output->writeln($debugFormatter->start(spl_object_hash($process), 'Some process description'));

This will output:

.. code-block:: text

RUN Some process description

You can tweak the prefix using the third argument::

$output->writeln($debugFormatter->start(spl_object_hash($process), 'Some process description', 'STARTED');
// will output:
// STARTED Some process description

Output Progress Information
---------------------------

Some programs give output while they are running. This information can be shown
using
:method:`Symfony\\Component\\Console\\Helper\\DebugFormatterHelper::progress`::

use Symfony\Component\Process\Process;

// ...
$process = new Process(...);

$process->run(function ($type, $buffer) use ($output, $debugFormatter, $process) {
$output->writeln(
$debugFormatter->progress(spl_object_hash($process), $buffer, Process::ERR === $type)
);
});
// ...

In case of success, this will output:

.. code-block:: text

OUT The output of the process

And this in case of failure:

.. code-block:: text

ERR The output of the process

The third argument is a boolean which tells the function if the output is error
output or not. When ``true``, the output is considered error output.
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The last sentence isn't necessary, is it? If you really want to make it more clear, you could write something like:

[...] if the output is error output (true is passed) or not.

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Well, I personally feel like true is a success, so using true to indicate an error message was quite surprising for me, that's why I've added the sentence explicitely.


The fourth and fifth argument allow you to override the prefix for the normal
output and error output respectively.

Stopping a Program
------------------

When a program is stopped, you can use
:method:`Symfony\\Component\\Console\\Helper\\DebugFormatterHelper::run` to
notify this to the users::

// ...
$output->writeln(
$debugFormatter->stop(
spl_object_hash($process),
'Some command description',
$process->isSuccessfull()
)
);

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Should this be run instead of progress? Or stop actually - that's what a I see in the initial PR for this feature.

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yeah, my bad :) Fixed it now

This will output:

.. code-block:: text

RES Some command description

In case of failure, this will be in red and in case of success it will be green.

Using multiple Programs
-----------------------

As said before, you can also use the helper to display more programs at the
same time. Information about different programs will be shown in different
colors, to make it clear which output belongs to which command.
1 change: 1 addition & 0 deletions components/console/helpers/index.rst
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Expand Up @@ -7,6 +7,7 @@ The Console Helpers
.. toctree::
:hidden:

debug_formatter
dialoghelper
formatterhelper
processhelper
Expand Down
1 change: 1 addition & 0 deletions components/console/helpers/map.rst.inc
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Expand Up @@ -6,3 +6,4 @@
* :doc:`/components/console/helpers/questionhelper`
* :doc:`/components/console/helpers/table`
* :doc:`/components/console/helpers/tablehelper`
* :doc:`/components/console/helpers/debug_formatter` (new in 2.6)