Sibele Lima Sibele Lima - 2 months ago 26
JSON Question

SQL 2016 - Converting XML to Json

I'm trying to convert a XML column to Json using FOR JSON PATH in SQL2016 but I'm having some issues. Given the following XML (note that some Product elements might have a list of Product inside):

<Request>
<SelectedProducts>
<Product id="D04C01S01" level="1" />
<Product id="158796" level="1" />
<Product id="7464" level="2">
<Product id="115561" level="3" />
</Product>
<Product id="907" level="2">
<Product id="12166" level="3" />
<Product id="33093" level="3" />
<Product id="33094" level="3" />
<Product id="28409" level="3" />
</Product>
<Product id="3123" level="2">
<Product id="38538" level="3" />
<Product id="37221" level="3" />
</Product>
</SelectedProducts>
</Request>


I can run the following statement on SQL (where @xml is the XML above):

SELECT
d.value('./@id', 'varchar(50)') AS 'Id'
,d.value('./@level', 'int') AS 'Level'
,(SELECT
--f.value('../@id', 'varchar(50)') AS 'ParentId'
f.value('./@id', 'varchar(50)') AS 'Id'
,f.value('./@level', 'int') AS 'Level'
--FROM @xml.nodes('/Request/SelectedProducts/Product[@id="3123"]/Product') AS e(f)
FROM @xml.nodes('/Request/SelectedProducts/Product/Product') AS e(f)
FOR JSON PATH) 'Product'
FROM @xml.nodes('/Request/SelectedProducts/Product') AS c(d)
FOR JSON PATH


The Json it generates is something like this:

[{"Id":"D04C01S01",
"Level":2,
"Product":[{"Id":"115561", "Level":3 }, {"Id":"12166","Level":3 }, { Id":"33093", "Level":3 }, {"Id":"33094","Level":3 }, {"Id":"28409","Level":3},
{"Id":"38538","Level":3},{"Id":"37221","Level":3 }]},

{"Id":"158796",
"Level":3,
"Product":[{"Id":"115561", "Level":3 }, {"Id":"12166","Level":3 }, { Id":"33093", "Level":3 }, {"Id":"33094","Level":3 }, {"Id":"28409","Level":3},
{"Id":"38538","Level":3},{"Id":"37221","Level":3 }]...


The problem as you can see is that in the Json generated all elements end up with all the Product regardless of their parent relationship.

I guess I am missing a WHERE clause where I would check it belongs to the parent node but I couldn't figure out how.

I tried to add a nodes Product[@id="3123"] (see commented line) but I need to replace the "3123" for the actual parent id and I don't know how to do it.

Another option was to actually save the parent id (see the commented line ParentId) and then using JSON_MODIFY in the result to delete the elements that didn't match but I wasn't successful also.

Does anyone have any ideas on how I can fix this? Or what else I could do?

-- EDIT
This is the Json that I am expecting:

[{"Request":
[{"Id":"D04C01S01","Level":1 },
{"Id":"158796","Level":1},
{"Id":"7464","Level":2,"Product":[{"Id":"115561","Level":3}]},
{"Id":"907","Level":2,"Product":[{"Id":"12166","Level":3},{"Id":"33093","Level":3},{"Id":"33094","Level":3},{"Id":"28409","Level":3}]},
{"Id":"3123","Level":2,"Product":[{"Id":"38538","Level":3},{"Id":"37221","Level":3}]}]}]


You may assume that if Level=1 then there will not be a Product sub-level and if Level=2 then there will be a Product sub-level.

Thank you

Answer Source

Your XPath on the inner node set is selecting all nodes from the XML and not just children of the outer node.

(I don't have a copy of SQL2016 on me but something like this should work.)

SELECT 
    d.value('./@id', 'varchar(50)') AS 'Id'
    ,d.value('./@level', 'int') AS 'Level'
    ,(SELECT 
        f.value('./@id', 'varchar(50)') AS 'Id'
        ,f.value('./@level', 'int') AS 'Level'
        FROM c.d.nodes('./Product') AS e(f)            
        FOR JSON PATH) 'Product'
FROM @xml.nodes('/Request/SelectedProducts/Product') AS c(d)
FOR JSON PATH