[wdmmg-dev] Proposed model overhaul

[Martin Keegan]

Can we link in the "before" and "after" examples?

On Tue, Oct 4, 2011 at 11:51 AM, Friedrich Lindenberg
<friedrich.lindenberg at okfn.org> wrote:
> Hi Martin,
>
> On Tue, Oct 4, 2011 at 12:36 PM, Martin Keegan <martin.keegan at okfn.org> wrote:
>>>> a payment in respect of which we want to record a value in more than
>>>> one currency?
>>>
>>> This, otoh, feels like its two ways of looking at the same payment
>>> (i.e. a split between currencies would duplicate the amount in the
>>> DB). One way to type for currency would be to have a flag on the
>>> measure to specify its currency on a per-measure basis, rather than
>>> per-dataset. I actually like this a lot, since it emphasises the fact
>>> that we deal with spending. We now can decide on how specific we want
>>> to be there (i.e. "USD" or "2010 USD" or "31.12.2009 USD").
>>
>> So, the main case I am thinking of is:
>>
>> you have a NGO which spends money in several currencies, and someone
>> has dumped their raw bank statements onto you (this is not
>> unrealistic), and these are in more than one currency (this is very
>> realistic indeed)
>
> I think we are talking about two separate issues here: one is a case
> of having the right data (e.g. spending in multiple currencies) and
> wanting to represent it - which is clearly within scope of the model
> language.
>
> The other issue is having incomplete data and wanting to infer the
> remaining data from what is there (e.g. filling up a measure with
> currency conversion). This, IMO, is very much outside the scope of the
> model language.
>
> If we are to include it, I propose we have a special section in the
> model (e.g. "pre-load-transform") and allow users to specify
> JSON-wrapped snippets of JavaScript that can will be executed by etl
> before import. This could then have a library function to perform
> currency conversion. The task specification language used could be
> that of Google Refine (I still want someone to re-implement the Refine
> service in Python for us and ScraperWiki to include).
>
> I just think that including more and more quasi-procedural options
> into the model format will lead us to doom (or re-building Windows
> NT).
>
> - Friedrich
>
> For reference, a Refine snippet:
>
> [
>  {
>    "op": "core/column-addition",
>    "description": "Create column name_munged at index 2 based on
> column name using expression grel:value.strip().toLowercase()",
>    "engineConfig": {
>      "facets": [],
>      "mode": "row-based"
>    },
>    "newColumnName": "name_munged",
>    "columnInsertIndex": 2,
>    "baseColumnName": "name",
>    "expression": "grel:value.strip().toLowercase()",
>    "onError": "set-to-blank"
>  }
> ]
>