[Geotools-gt2-users] PostGIS Schema from empty GeoJSON set

[Patrick D <tru...@gm...>]

Hello,

I'm attempting to create a schema for some input GeoJSON so that I can
store this data using PostGIS transactions. I am experiencing a problem
with input that is an empty GeoJSON set.

```
{"type": "FeatureCollection", "features": []}
```

This is valid GeoJSON, so I'd like to support this case. I am retrieving a
PostGIS data store and then creating a schema for this GeoJSON.

```
FeatureJSON featureJSON = new FeatureJSON();
SimpleFeatureType featureSchema =
featureJSON.readFeatureCollectionSchema(inputStream, false);
DataStore postGisStore = GeoToolsUtil.getPostGisDataStore(/*params*/);
postGisStore.createSchema(featureSchema);
```

The final line throws an error because it cannot find the default geometry
field. This is because, for my empty GeoJSON set, there's obviously no
geometry and no attributes.

If I turn on FINEST logging, I can see the commit statement that is failing:

`FINE: Create schema: CREATE TABLE "public"."feature" ( "fid" SERIAL
PRIMARY KEY,  )`

The SQL statement is attempting to set a primary key, but since my GeoJSON
is empty, no value exists.

Is there a way I can get this schema creation to succeed with an empty
GeoJSON set? I would like to add more feature data to it later, but I would
like to handle table creation immediately upon being provided with this
initial GeoJSON.

Thanks.