Apache metamodel example for CouchDB

Question

I am tasked with using Apache Metamodel with CouchDB and Node.js. Despite trying it out in google, i could not get an example for the same. Th examples found seem to be more suited for RDBMS! Can i get an example to connect to couchdb, list all dbs, fetch a document and insert document and attachments?

Answer 1

Assuming you have documents a la this one:

{
 "name": "John Doe",
 "address:" {
  "street": "21 3rd street"
 },
 "age": 42
}

Then you could query it like this:

CouchDbDataContext dc = ...;
DataSet ds = dc.query().from("my_database").select("name", "address", "age").execute();
while (ds.next()) {
  Row r = ds.getRow();
  String name = (String) r.getValue(0);
  Map<String,?> address = (Map<String, ?>) r.getValue(1);
  Number age = (Number) r.getValue(2);
}
ds.close();

And then to insert:

dc.executeUpdate(new UpdateScript() {
  public void run(UpdateCallback cb) {
    cb.insertInto("my_database").value("name", "Jane Doe").value("age", 43).execute();
  }
});

Does it mostly work for RDBMSes? I wouldn't say so. But it is correct that Apache MetaModel attempts to make a unified view on all datastore types which includes mapping them to a table/column/row abstraction which is obviously an interpretation on top of something like CouchDB. The advantage is of course that the above code snippets could just as well work on a CSV file, a SQL table or any other datastore type that MetaModel supports.