# Unclear interaction of SMS2 FROM JSON with arrays **URL:** \ **Category:** Support\ **Created:** [August 4, 2023, 1:26pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522 "2023-08-04T13:26:39Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Boris\_Pelakh](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.stardog.com/boris_pelakh/32/1890_2.png) [@Boris\_Pelakh](https://community.stardog.com/u/Boris_Pelakh)\ **Post date:** [August 4, 2023, 1:26pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/1 "2023-08-04T13:26:39Z")
If I run SMS on a CSV, the order of bindings is pretty obvious - every row of the CSV is fed into the `WHERE` section, and the resulting bindings are then used to build the triples in the `TO` section. In this case, if do a `BIND(UUID() as ?row)` and then assert `?row a :Row`, I should expect one triple for each row in the CSV However, If I have a nested JSON data structure with arrays of varying sizes, e.g. ```auto { "elements": [ { "eid": 1, "props": { "A": [ { "pid": "1-A1" }, { "pid": "1-A2" } ], "B": [ { "pid": "1-B1" }, { "pid": "1-B2" }, { "pid": "1-B3" } ] } } ] } ``` which I then map with ```auto MAPPING :json_test FROM JSON { { "elements": [ { "eid": "?eid", "props": { "A": [ { "pid": "?prop_a_id" } ], "B": [ { "pid": "?prop_b_id" } ] } } ] } } TO { ?input_set :bindings ?bindings } WHERE { bind(uuid() as ?input_set) BIND(CONCAT(STR(?eid),'-', COALESCE(?prop_a_id, 'NO_A'),'-', COALESCE(?prop_b_id, 'NO_B') ) as ?bindings) } ``` would it result in a DFS traversal of the JSON structure with an input set emitted into the WHERE/TO at each leaf, i.e. I should expect 5 UUIDs bound with the inputs being ```auto {eid:1,a_prop_id:"1-A1"} {eid:1,a_prop_id:"1-A2"} {eid:1,b_prop_id:"1-B1"} {eid:1,b_prop_id:"1-B2"} {eid:1,b_prop_id:"1-B3"} ``` because what I am seeing is quite different - I am seeing a single UUID bound to a cross product (6 values) of As and Bs. It gets even more interesting if not all values are populated - if the B array is empty, for example, I will get 2 bindings, one with each A value + '-NO\_B', but if the 'B' element is removed entirely, I get no bindings, even though A values are there. Is there a way to make a sub-tree as optional? ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [September 11, 2023, 5:32pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/2 "2023-09-11T17:32:45Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [October 24, 2023, 5:51pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/3 "2023-10-24T17:51:16Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [December 11, 2023, 7:22pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/4 "2023-12-11T19:22:24Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [February 2, 2024, 2:50pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/5 "2024-02-02T14:50:43Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [March 30, 2024, 7:19pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/6 "2024-03-30T19:19:54Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [June 27, 2024, 10:43am UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/7 "2024-06-27T10:43:54Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [December 30, 2024, 8:16am UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/8 "2024-12-30T08:16:27Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [August 4, 2025, 11:09am UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/9 "2025-08-04T11:09:18Z")
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**Author:** ![system](https://canada1.discourse-cdn.com/flex030/uploads/stardog/original/2X/e/ed66b48a616f505106a4acde3c9cee7e6da9bc67.svg) [@system](https://community.stardog.com/u/system)\ **Post date:** [March 28, 2026, 2:16pm UTC](https://community.stardog.com/t/unclear-interaction-of-sms2-from-json-with-arrays/4522/10 "2026-03-28T14:16:04Z")