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From Rohit Yadav <rohityada...@gmail.com>
Subject Re: [PROPOSAL][QUESTION] Map parameters in API Commands
Date Tue, 11 Feb 2014 16:38:47 GMT
Hi Antonio,

On Tue, Feb 11, 2014 at 9:57 PM, Antonio ForniƩ Casarrubios
<antonio.fornie@gmail.com> wrote:
> Hi all,
>
> When invoking a CS API command that has parameters of type Map, the request
> will be something like this:
> URL/api?command=createTags&tags[0].key=region&tags[0].value=canada&tags[1].key=name&tags[1].value=bob
>
> in order to send a Map with the pairs:
>
> tags{
>    region : "canada",
>    name : "bob"
> }
>
> Then in the server side the parameters go through several stages (IMHO too
> many), and have different formats. At some point
>
> apiDispatcher#setFieldValue
>
> will assign the value to the command property (CreateTagsCmd#tag in the
> example) in a VERY strange way:
>
> CreateTagsCmd#tag = {
>    0 : {
>       "key" : "region",
>       "value" : "canada"
>    },
>    1 : {
>       "key" : "name",
>       "value" : "bob"
>    }
> }
>
> This is true for several Cmd classes. And the funny thing is they usually
> provide a public getter method to get the Map in an already "normalized"
> structure. The problem is we have this method again a again in each of
> these commands, only with different name depending on what property the
> get, and the body is almost copy and pasted. so my next refactoring would
> be to have a generic method only once in BaseCmd so that all subclasses can
> reuse it for their Map getters. Pretty obvious, but...

This is a well know issue and is such a pain, both for the users of
the API to create this API and the programmer who have to put hack at
the backend to extract the map.

> Is it really necessary to have this strange format? Wouldn't it be much
> better to just store it in a more normal way from the beginning, and have
> the getters just standard getters? Does it have any use to have those Maps
> of Maps?

Changing the API will break many client so no one attempted it for
keeping backward-compatibility I think.

The HTTP RFC states that if same keys are sent in param they must be
received as an array. For example, /api?q=1&q=2&q=3 should received q
= [1,2,3] which is what we're not doing.

We should do that and this way we can capture maps using keys and
values in order, so for example,
/api?q.key1=value1&q.key2=value2&q.key1=value3&q.key2=value4 should be
received as as array of maps: [{key1: value1, key2: value2},
{key3:value3, key4: value4}] etc.

I think it does not have to be maps of maps, but since our API is
query based these ugly hacks were invented. We should definitely get
rid of them, and perhaps work on the RESTful API layer, cloud-engine
and other good stuff we were talking about more than a year ago and
deprecate the present query API over next few years. Thoughts, flames?

Regards.

>
> Thanks. Cheers
> Antonio Fornie
> Schuberg Philis - MCE

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