Allow property.select to override the property field name.

[kapouer]

This is a generic way to address
#273
Important: property.select can be a function, whose
return value won't be escaped.

I'll happily add a test and modify readme.md if that PR is ok.

[dxg]

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?

[kapouer]

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)";
        };
    }
});

[bblack]

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.

[dresende]

@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.

[dxg]

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.

[kapouer]

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.

[unibasil]

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.

[dxg]

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

[dxg]

@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.

[dxg]

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

[kapouer]

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

[unibasil]

Great, thank you.