FluidDB Tags in 10 Minutes

So, with your namespaces structured it’s now time to add tags.

I’ll assume you already have a FluidDB session open. To add a tag to your current namespace:

>>> namespace.tag_names
>>> namespace.create_tag( "foo", "behold: the foo tag", False )
<FluidResponse (201, 'application/json', None, {'id': 'cac795ce-777f-4d64-94cc-6df5356eb651', 'URI': 'http://fluiddb.fluidinfo.com/tags/metaljoe/foo'})>
>>> namespace.tag_names

Okay, let’s take a look at that in more detail. The create_tag() method has three arguments: the tag name, the tag description and a mysterious boolean value at the end. The last value specifies whether the tag should be indexed – in this case, I have left it unindexed. At present, I’m not sure how the indexing works or if it gives any noticeable advantages at present. I should really make an effort to find out….

When my tag has been created, FOM returns a response from FluidDB. For those not fluent in HTTP, 201 is the Created response status: my tag was successfully created. You can also see that FluidDB has assigned my tag a unique GUID, and that the URI of my tag is http://fluiddb.fluidinfo.com/tags/metaljoe/foo – everything in FluidDB can be referenced by a URL, FluidDB’s RESTful API, and everything has a GUID.

>>> namespace.tag_paths

Yup, that looks pretty conclusive.

Having a tag defined is one thing, the power of that tag comes when you apply it to objects in the system. Let’s find a suitable object first:

>>> from fom.mapping import Object
>>> mars = Object(about="planet:Mars")
>>> mars
<Object planet:Mars>

Tagging the object is trivial:

>>> mars.set( "metaljoe/foo", None )

As is retrieving the value of that tag:

>>> mars.get( "metaljoe/foo" )
(None, 'application/vnd.fluiddb.value+json')

Now, setting the value to None is pretty dull. How about we set it to something more interesting?

>>> mars.set( "metaljoe/foo", "The red planet" )
>>> mars.get( "metaljoe/foo" )
('The red planet', 'application/vnd.fluiddb.value+json')

Actually, we might not want the value set in the system as a FluidDB JSON value. Let’s try setting it to the text/plain MIME type:

>>> mars.set( "metaljoe/foo", "The red planet", "text/plain" )
>>> mars.get( "metaljoe/foo" )
('The red planet', 'text/plain')

Python lists can also be stored easily enough:

>>> mars.set( "metaljoe/foo", ["The red planet", "My favourite planet"] )
>>> mars.get( "metaljoe/foo" )
(['My favourite planet', 'The red planet'], 'application/vnd.fluiddb.value+json')

Finally, tags have their own class in FOM:

>>> from fom.mapping import Tag
>>> tag = Tag( "metaljoe/foo" )
>>> tag
<fom.mapping.Tag object at 0x5b62d0>
>>> tag.description
'behold: the foo tag'

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