If you have time, I posted a gist containing a data access library I built
on top of Rich's sdb library (data.clj), and the modifications I made to his
sdb library (sdb.clj) for consistent reads, etc. This is some of the first
real clojure code I wrote, so not the prettiest, but maybe you can see some
of the pain points I had using the current sdb library.
To summarize:
- Whether or not to add asynchronous client support
- Not a nice generic way of building up select dsl maps
- I believe the select dsl 'where' clause only handles up to two predicates
- How to account for nil / blank values
- Automatically sync domains with a specified list
Certainly some of this belongs above the level of the sdb library, but some
of it should be handled there.
- Mark
On Sun, Feb 27, 2011 at 9:15 AM, Gijs S. <gijsstuur...@gmail.com> wrote:
> Yes, my suggestion without type indicators in SDB would look something
> like this:
>
> (def config {:sdb-client (AmazonSimpleDBClient. ...)
> :mapping {"Link" {"url" {:encode encode-string :decode
> decode-string}
> "points" sdb/integer-encoding
> "date" {:encode encode-jodadate :decode
> decode-jodadate}}
> "AnotherDomain" {...}})
>
> sdb/integer-encoding would be a library provided encoding/decoding
> map.
>
> In this approach each encoding/decoding pair is defined at the level
> of an attribute in a domain.
>
> A (get-attr config "Link" "id") will go through the mapping in the
> config to create a clojure datastructure with each attr properly
> decoded.
>
> A mapping map would allow for a bit more composition then one big
> encode fn in the config where a case construct needs to be extended
> for each attribute. For instance the mapping could be constructed like
> this: {:mapping (merge link-domain-map another-domain-map ...)}.
> Perhaps a library could provide a macro that expands (defdomain Link
> [url :string, point :int, date {:encode .. :decode ..}]) into such a
> mapping map.
>
> Because this approach doesn't have any type indicators in SDB, every
> attribute needs to have an encoding/decoding defined or there needs to
> be a default encode/decoding, which for Clojure could be print-string/
> read-string.
>
> -Gijs
>
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