Trouble iterating over resultset and generating json - sql

Question

I am struggling a bit trying to generate some JSON from a query I execute. All of the groovy JsonBuilder examples I've looked at only seem to deal with statically defining a dataset.
code:
def db = new Sql(datasource)
def builder = new JsonBuilder()
db.eachRow('SELECT t.day, t.start FROM mytable') { row ->
builder.days {
day(
date row.day
)
}
}
println builder.toString()
I had it at 1 point where it was printing only the last value in the resultset out.
Currently I am receiving the following error:
unexpected token: $ # line 46, column 18.
date row.day
I'm still a bit of a novice at groovy, any help greatly appreciated.

Answer 1

I generally prefer to present JsonBuilder with a complete object rather than use the DSL, so my solution would look something like this:
def map = [days:[]]
def db = new Sql(dataSource)
db.eachRow('SELECT t.day, t.start FROM mytable') { row ->
map.days << [day : [date: row.day]]
}
println new JsonBuilder(map).toString()
If you have a large number of results, this approach has the advantage of not forcing you to compile a huge list of GroovyRowResult objects, only a huge list of much smaller LinkedHashMap objects.

Answer 2

The builder there does not opening a list, add items, then close it. you would have to provide it in a single go. E.g. collect all rows as maps:
def builder = new groovy.json.JsonBuilder()
def dbresult = [1,2,3]
builder {
days dbresult.collect{
[day: [date: it]]
}
}
println builder
Use db.rows to get the list. You might have to try, what is happening, if you just send in the result. Maybe needs a cast to a Map or you have to do the mapping yourself.
If your rowcount is very high, you might be better off some other library, that don't need you to manifest the list beforehand.