Groovy's SQL support allows us to access ResultSetMetaData with a closure when we use the query methods rows() and eachRow(). We can pass a closure as the last argument of these methods. The closure parameter is the ResultSetMetaData object. The closure is only invoked once after the query is executed.
@Grapes([
@Grab(group='com.h2database', module='h2', version='1.3.160'),
@GrabConfig(systemClassLoader = true)
])
import com.h2database.*
import groovy.sql.*
def db = Sql.newInstance('jdbc:h2:mem:', 'sa', '', 'org.h2.Driver')
// Setup database.
db.execute '''
create table if not exists languages(
id int primary key,
name varchar(20) not null
)
'''
db.execute "insert into languages values(1, 'Groovy')"
db.execute "insert into languages values(2, 'Java')"
// Sample of meta closure:
String query = 'select id as identifier, name as langName from languages'
def rows = db.rows(query, { meta ->
assert meta.tableName == 'languages'
assert meta.columnCount == 2
assert meta.getColumnLabel(1) == 'IDENTIFIER'
assert meta.getColumnName(1) == 'ID'
assert meta.getColumnTypeName(1) == 'INTEGER'
assert meta.getColumnLabel(2) == 'LANGNAME'
assert meta.getColumnName(2) == 'NAME'
assert meta.getColumnTypeName(2) == 'VARCHAR'
})
