How to select field from a sibling array? - couchbase

Question

I would like to select value ('Value') from element with FieldName=Field4 where value ('Value') is null from element with FieldName=Field2.
{
"FormName":"Form1",
"Id": "ID1",
"Module":{
"ModuleType":"Form",
"Layout":"Vertical",
"ControlList":[
{
"ControlType":"Widget",
"Layout":"Vertical",
"FieldList":[
{
"FieldType":"TextBox",
"FieldName":"Field1",
"Value":"field1"
},
{
"FieldType":"TextBox",
"FieldName":"Field2",
"Value":null
},
{
"FieldType":"TextBox",
"FieldName":"Field1",
"Value":"field3"
}
]
},
{
"ControlType":"Widget",
"Layout":"Vertical",
"FieldList":[
{
"row":[
{
"FieldType":"TextBox",
"FieldName":"Field3",
"Value":"field3"
},
{
"FieldType":"TextBox",
"FieldName":"Field4",
"Value":"field4"
}
]
}
]
}
]
}
}
I understand how to get the right dataset:
select
form.Id
from
`test` as form
where
any cl in form.Module.ControlList satisfies
any fl in cl.FieldList satisfies fl.FieldName = 'Field2' AND fl.`Value` is null
end
end;
... returning:
[
{
"Id": "ID1"
}
]
But how should my select statement look like to get this:
[
{
"Value": "field4"
}
]

Answer 1

Use ARRAY construct
SELECT
ARRAY_FLATTEN((ARRAY (ARRAY (ARRAY {r.`Value`}
FOR r IN f.`row`
WHEN r.FieldName = "Field4"
END)
FOR f IN c.FieldList
END)
FOR c IN t.Module.ControlList
END),3)[0].*
FROM `test` AS t
WHERE (ANY cl IN t.Module.ControlList
SATISFIES (ANY fl IN cl.FieldList
SATISFIES fl.FieldName = 'Field2' AND fl.`Value` IS NULL
END)
END);