🔖 Tags

You can define custom groupings of pipes with tags. Consider the example below:

Although both pipes have different connectors and metrics, they share the tag baz, so they can be selected together with --tags baz.

Selecting Pipes with Tags

The --tags syntax is simple yet powerful:

• Spaces are joined by OR.
• Commas are joined by AND.
• Underscores negate tags, overriding OR and AND.

You can read groups of tag pairs with commas. For example, the following will select pipes tagged as both red and cat or as blue and dog:

mrsm show pipes --tags red,cat blue,dog

Prefixing any tag with an underscore will negate it from the entire selection. The following selects all pipes tagged as pet except those tagged as bird:

mrsm show pipes --tags pet _bird

Examining Tags

Like show pipes, the action show tags accepts the standard filter flags (-c, -m, -l, -t) and displays pipes grouped together by common tags (with repeats as necessary).

Use positional arguments (instead of --tags) to limit the output of show tags to specific tags.

In the above example, we have four pipes:

• Greenville weather (gvl)
• Clemson weather (clemson)
• Atlanta weather (atl)
• Athens colors (athens)

Three tags are shared amongst these pipes:

• ga (Georgia)
• sc (South Carolina)
• production

From the screenshot, we can quickly tell that:

• atl and athens are tagged with ga.
• clemson and gvl are tagged with sc.
• atl, clemson, and gvl are tagged as production.

Even though we only specified the tags sc and ga, the mutual tag production was included in the output. This can be omitted by specifying the tags as positional arguments:

mrsm show tags sc ga

Writing Tags

The quickest way to write tags is with the tag pipes action:

mrsm tag pipes production -c sql:main

Note that new tags must be specified as positional arguments ― the flag --tags is used for filtering.

Removing Tags

You may also remove tags with the action tag pipes by prefixing tags with an underscore. In this example, we are removing the tag production from all pipes currently tagged as production.

mrsm tag pipes _production --tags production

Tags in Python

You can define tags in the Pipe constructor:

>>> import meerschaum as mrsm
>>> mrsm.Pipe(
...   "sql:foo", "bar",
...   tags = ['tag1', 'tag2'],
... )
>>>

Tags Live in Parameters

To edit your tags interactively, just define a list under the tags key with edit pipes:

mrsm edit pipes -c sql:foo -m bar

tags:
  - tag1
  - tag2
columns:
  datetime: date
  id: station_id

Finally, you can also add tags to an existing pipe by setting .tags:

>>> import meerschaum as mrsm
>>> pipe = mrsm.get_pipes(as_list=True)[0]
>>> pipe.tags = ['tag1', 'tag2']
>>> pipe.edit() ### Persist the tags in the database.