[ckan-dev] what are context and data_dicts?

[Adrià Mercader]

Hi George,

As you will have noticed, all functions from the logic layer accept
the context and data_dict parameters.
The context provides information about the environment in which a
function is executed (ie the context). Generally the more important
pieces of information that you need are the model and the user that is
performing the action, so the authorization checks can be performed.
It can also have other keys specific to each function.

data_dict is the actual data that the function will use. For functions
that eg interact with datasets like package_create or package_update
this is the actual dataset dict that will get added or updated on the
database. In others like the "current_package_list_with_resources"
case they hold parameters that affect the returned value. The keys
shown on the docs (eg [1]) are the ones that go on package dict.

The good news is that if you use get_action, the context object is
automatically populated for you with the model and user keys, so you
don't need to worry about it. BTW, always use get_action from the
plugins toolkit when writing extensions, that way your extension will
keep working if we change the implementation on CKAN core.

So, for example if you only want 10 datasets starting from page 2:

import ckan.plugins as p
result = p.toolkit.get_action('current_package_list_with_resources')({},{'limit':
10, 'page': 2})


Hope this helps,

Adrià



[1] http://docs.ckan.org/en/latest/ckan.logic.action.get.html#ckan.logic.action.get.current_package_list_with_resources

On 16 May 2013 03:56, George Sattler <George.sattler at xvt.com.au> wrote:
> Hello Everyone.
>
>
>
> I am writing an extension and I want to use:
>
> result = ckan.logic.get_action('current_package_list_with_resources')()
>
>
>
> Or even just on command line (without the recommended use of ‘get_action’):
>
> result = ckan.logic.action.get.current_package_list_with_resources()
>
>
>
> However this function requires that you pass it ‘context’ and a ‘data_dict’
> objects. I have no idea what exactly these objects are or how I can generate
> them and the documentation here
> http://docs.ckan.org/en/latest/ckan.logic.action.get.html#ckan.logic.action.get.current_package_list_with_resources
> doesn’t seem clear enough (to me, anyway).
>
>
>
> Would someone please be able to explain what params I should be supplying.
>
>
>
> Thanks
>
> George
>
>
>
>
>
>
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