SQL query to return Json including array - json

Question

I have a relational database (SQL Server) with normal data.
I am trying to build something with this format:
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"id": "1",
"properties": { "address": "2" },
"geometry": {
"type": "Point",
"coordinates": [36.33456, 59.523456]
}
},
{
"type": "Feature",
"id": "2",
"properties": { "address": "151" },
"geometry": {
"type": "Point",
"coordinates": [36.33456, 59.523456]
}
}]
}
So far I have written this query:
select top 10
'Feature' as [type],
m.Id as id, m.Address as 'properties.address',
'Point' as 'geometry.type',
'[' + m.location + ']' as 'geometry.coordinates'
from
Buildings m
where
m.Location is not null
and m.Location <> ''
for json path, root('features')
But what I receive in action is like:
{
"features": [{
"type": "Feature",
"id": 250343,
"properties": {
"address": "there"
},
"geometry": {
"type": "Point",
"coordinates": "[5714843008,3363769468.235179]"
}
}, {
"type": "Feature",
"id": 266306,
"properties": {
"address": "here"
},
"geometry": {
"type": "Point",
"coordinates": "[36.38449104993326,59.48238372802735]"
}
}}
How can I add "type": "FeatureCollection", before the root?
I want the coordinate part to hold an array of 2 numbers, but in my current code it is a string holding the array. How can I achieve an array?

Answer 1

It's difficult without test data, but I think that you can build the expected JSОN output using the following statement. You need one more FOR JSON PATH (to generate the outer JSON object) and a JSON_QUERY call (to return a JSON array of scalar values instead of text holding the array):
Table:
CREATE TABLE Buildings (
Id int,
Address varchar(100),
Location varchar(100)
)
INSERT INTO Buildings (Id, Address, Location)
VALUES
(250343, 'there', '5714843008,3363769468.235179'),
(266306, 'here', '36.38449104993326,59.48238372802735')
Statement:
SELECT
[type] = 'FeatureCollection',
[features] = JSON_QUERY((
select top 10
'Feature' as [type],
m.Id as id, m.Address as 'properties.address',
'Point' as 'geometry.type',
JSON_QUERY('[' + m.location + ']') as 'geometry.coordinates'
from
Buildings m
where
m.Location is not null
and m.Location <> ''
for json path
))
FOR JSON PATH, WITHOUT_ARRAY_WRAPPER
Result:
{
"type":"FeatureCollection",
"features":[
{
"type":"Feature",
"id":250343,
"properties":{
"address":"there"
},
"geometry":{
"type":"Point",
"coordinates":[
5714843008,
3363769468.235179
]
}
},
{
"type":"Feature",
"id":266306,
"properties":{
"address":"here"
},
"geometry":{
"type":"Point",
"coordinates":[
36.38449104993326,
59.48238372802735
]
}
}
]
}

Answer 2

I figured a way to build custom JSON using STUFF (GROUP_CONCAT in MySQL) and XML.
See if this works for you:
1 Answer to question 1 - Note, this is a TWO-STEP PROCESS:
a) VARIABLE TO HOLD QUERY DATA
DECLARE #QUERY_DATA varchar(8000)
b) CUSTOM QUERY TO FETCH QUERY DATA FORMATTED FOR INNER JSON METADATA (all in one line)
SET #QUERY_DATA = (
SELECT STUFF(
(
SELECT ',' + CONCAT('{"type": "Feature","id": ', m.Id, ',"properties": {"address": "', m.Address, '"},"geometry": {"type": "Point","coordinates": [', m.location, ']}}'
)
FROM
Buildings m
WHERE
m.Location is not null
and m.Location <> ''
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '')
+)
c) FINAL OUTPUT - Concatenate / Join your JSON
SELECT CONCAT('{ ''type'':''FeatureCollection''','','',',''FEATURES'': [ ', #QUERY_DATA, ' ] }')
2 - ANSWER TO QUESTION 2 with CONSOLIDATED solution using separated X and Y coordinates as two INTEGER Type elements
{''X'':', CAST(LEFT( m.location, CHARINDEX(',', m.location)-1) as int), ',''Y'':', cast(RIGHT( m.location, LEN( m.location)-CHARINDEX(',', m.location)) as int),'}
Therefore, when we add this together, your new query would look like the following:
a) VARIABLE TO HOLD QUERY DATA
+DECLARE #QUERY_DATA varchar(8000)
b) CUSTOM QUERY TO FETCH QUERY DATA FORMATTED FOR INNER JSON METADATA (all in one line), including splitting coordinates into two INTEGER Type elements
SET #QUERY_DATA = (
SELECT STUFF(
(
SELECT ',' + CONCAT('{"type": "Feature","id": ', m.Id, ',"properties": {"address": "', m.Address, '"},"geometry": {"type": "Point","coordinates": [ {''X'':', CAST(LEFT( m.location, CHARINDEX(',', m.location)-1) as int), ',''Y'':', cast(RIGHT( m.location, LEN( m.location)-CHARINDEX(',', m.location)) as int),'}]}}'
)
FROM
Buildings m
WHERE
m.Location is not null
and m.Location <> ''
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)'), 1, 1, '')
+)
c) FINAL OUTPUT - Concatenate / Join your OUTER and INNER JSON
SELECT CONCAT('{ ''type'':''FeatureCollection''','','',',''FEATURES'': [ ', #QUERY_DATA, ' ] }')