Allow property.select to override the property field name. - #375

I would call it something like mapsTo rather than column so it generalizes for non SQL stores.
As far as I can see you would like to:
1/ be able to name the model property differently than in the datastore
2/ be able to do a custom transform for a field?? I'm not sure. What is select for?

Yes, it kills two birds with one stone.
The second case allows customization - code that is specific to a driver.
Things like this:

orm.db.defineType('GeoJSON', {
    datastoreType: function(prop) {
        return 'geometry(Geometry, 4326)';
    },
    datastoreSelect: function(prop, helper) {
        return 'ST_AsGeoJSON(' + prop + ') AS ' + prop;
    },
    valueToProperty: function(value, prop) {
        if (value == null) return function() { return 'NULL'; };
        else if (typeof value == "string") return JSON.parse(value);
        else return value;
    },
    propertyToValue: function(value, prop) {
        if (value == null) return value;
        else return function(h) {
            return "ST_SetSRID(ST_GeomFromGeoJSON(" + h.escapeVal(JSON.stringify(value)) + "), 4326)";
        };
    }
});

I haven't looked at any node-orm2 code so I can't comment on the content of this PR, but I am interested in getting this feature.

@dxg I agree with you, I would prefer something like mapsTo or mapping or something like that. Since I've merged sql-ddl-sync with this module, this also has to be passed on to it, so the correct column/property name is used when synching.

We have the concept of custom datatypes - which I think covers # 2. See this test.

Point # 1 sounds like a definite one for the todo list.

While i understand the "datastoreSelect" function looks a bit like a trick, the fact it allows more than just
an alias is necessary in that case because it's an actual call to a conversion function
that is available in the postgis database (and quite difficult to emulate to javascript).
Of course, it binds the model to a specific database, and being able to do that while still keeping the
nice API of orm is why i chose it over other orm modules.

How can I upvote this commit? ;) Possibility of using above mentioned pair of ST_AsGeoJSON() and ST_GeomFromGeoJSON() functions over column in table is exactly what I need. It will be great to make it public.

I've added this to the next milestone.
Hopefully get to it soon.

@kapouer , @unibasil and any other PostGIS users out there, please install the custom-properties branch by modifying your package.json:

"orm": "https://github.com/dresende/node-orm2.git#custom-properties",

(you may need to rm node_modules/orm)

There is a sample test showing the new functionality here:
custom-properties/test/integration/property-custom.js#L75.

I need to know if this works with PostGIS, or if something else needs to be done.
Consider the custom-properties branch as experimental, so other things may be broken (tests do pass though).
datastoreGet should be analogous to datastoreSelect in the example above.

The PR has been merged. Basic PostGIS support should now be available, however I suspect more work will be needed for complete PostGIS support.

it works quite nicely - thank you.
datastoreGet works all right.

Great, thank you.