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when a to-many spread has only aggregates selected, then it's not wra…
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…pped in an array (treated as a to-one spread)
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@laurenceisla
laurenceisla committed Jan 2, 2025
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25 changes: 25 additions & 0 deletions docs/references/api/aggregate_functions.rst
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Expand Up @@ -318,3 +318,28 @@ For example:
"order_date": ["2023-09-01", "2023-09-03"]
}
]
However, there is an exception. If only aggregates are selected, i. e. if there is no other columns to group by, then we can always expect a single row to be returned.
So, we don't wrap the single result in an array and show it directly.
For example, if we do not group by the ``order_date`` anymore:

.. code-block:: bash
curl "http://localhost:3000/customers?select=name,city,state,...orders(amount.sum())"
.. code-block:: json
[
{
"name": "Customer A",
"city": "New York",
"state": "NY",
"sum": 1120.95
},
{
"name": "Customer B",
"city": "Los Angeles",
"state": "CA",
"sum": 755.58
}
]
23 changes: 15 additions & 8 deletions src/PostgREST/Plan.hs
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Expand Up @@ -329,8 +329,8 @@ readPlan qi@QualifiedIdentifier{..} AppConfig{configDbMaxRows, configDbAggregate
in
mapLeft ApiRequestError $
treeRestrictRange configDbMaxRows (iAction apiRequest) =<<
hoistSpreadAggFunctions =<<
addToManySpreadOrderSelects =<<
hoistSpreadAggFunctions =<<
validateAggFunctions configDbAggregates =<<
addRelSelects =<<
addNullEmbedFilters =<<
Expand Down Expand Up @@ -749,15 +749,22 @@ hoistIntoRelSelectFields aggList r@(Spread {rsSpreadSel = spreadSelects, rsAggAl
Nothing -> s
hoistIntoRelSelectFields _ r = r

-- | Handle ordering in a To-Many Spread Relationship
-- In case of a To-Many Spread, it removes the ordering done in the ReadPlan and moves it to the SpreadType.
-- We also select the ordering columns and alias them to avoid collisions. This is because it would be impossible
-- to order once it's aggregated if it's not selected in the inner query beforehand.
-- | Handle aggregates and ordering in a To-Many Spread Relationship
-- It does the following in case of a To-Many Spread
-- * When only aggregates are selected (no column to group by), it's always expected to return a single row.
-- That's why we treat these cases as a To-One Spread and they won't be wrapped in an array.
-- * It removes the ordering done in the ReadPlan and moves it to the SpreadType.
-- We also select the ordering columns and alias them to avoid collisions. This is because it would be impossible
-- to order once it's aggregated if it's not selected in the inner query beforehand.
addToManySpreadOrderSelects :: ReadPlanTree -> Either ApiRequestError ReadPlanTree
addToManySpreadOrderSelects (Node rp@ReadPlan { order, relAggAlias, relSpread = Just ToManySpread {}} forest) =
Node rp { order = [], relSpread = newRelSpread } <$> addToManySpreadOrderSelects `traverse` forest
addToManySpreadOrderSelects (Node rp@ReadPlan{order, select, relAggAlias, relSelect, relSpread = Just ToManySpread {}} forest) =
Node rp { order = newOrder, relSpread = newRelSpread } <$> addToManySpreadOrderSelects `traverse` forest
where
newRelSpread = Just ToManySpread { stExtraSelect = addSprExtraSelects, stOrder = addSprOrder}
(newOrder, newRelSpread)
| allAggsSel && allAggsRelSel = (order, Just ToOneSpread)
| otherwise = ([], Just ToManySpread { stExtraSelect = addSprExtraSelects, stOrder = addSprOrder})
allAggsSel = all (isJust . csAggFunction) select
allAggsRelSel = all (\case Spread sels _ -> all (isJust . ssSelAggFunction) sels; _ -> False) relSelect
(addSprExtraSelects, addSprOrder) = unzip $ zipWith ordToExtraSelsAndSprOrds [1..] order
ordToExtraSelsAndSprOrds i = \case
CoercibleOrderTerm fld dir ordr -> (
Expand Down
159 changes: 91 additions & 68 deletions test/spec/Feature/Query/AggregateFunctionsSpec.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -306,87 +306,95 @@ allowed =
it "supports the use of aggregates without grouping by any fields" $ do
get "/factories?select=name,...factory_buildings(size.sum())" `shouldRespondWith`
[json|[
{"name":"Factory A","sum":[350]},
{"name":"Factory B","sum":[170]},
{"name":"Factory C","sum":[240]},
{"name":"Factory D","sum":[310]}]|]
{"name":"Factory A","sum":350},
{"name":"Factory B","sum":170},
{"name":"Factory C","sum":240},
{"name":"Factory D","sum":310}]|]
{ matchHeaders = [matchContentTypeJson] }
it "supports many aggregates at the same time" $ do
get "/factories?select=name,...factory_buildings(size.min(),size.max(),size.sum())" `shouldRespondWith`
[json|[
{"name":"Factory A","min":[150],"max":[200],"sum":[350]},
{"name":"Factory B","min":[50],"max":[120],"sum":[170]},
{"name":"Factory C","min":[240],"max":[240],"sum":[240]},
{"name":"Factory D","min":[310],"max":[310],"sum":[310]}]|]
{"name":"Factory A","min":150,"max":200,"sum":350},
{"name":"Factory B","min":50,"max":120,"sum":170},
{"name":"Factory C","min":240,"max":240,"sum":240},
{"name":"Factory D","min":310,"max":310,"sum":310}]|]
{ matchHeaders = [matchContentTypeJson] }
it "supports aggregates inside nested to-one spread relationships" $ do
get "/supervisors?select=name,...processes(...process_costs(cost.sum()))&order=name" `shouldRespondWith`
[json|[
{"name":"Jane","sum":[null]},
{"name":"John","sum":[270.00]},
{"name":"Mary","sum":[220.00]},
{"name":"Peter","sum":[290.00]},
{"name":"Sarah","sum":[180.00]}]|]
{"name":"Jane","sum":null},
{"name":"John","sum":270.00},
{"name":"Mary","sum":220.00},
{"name":"Peter","sum":290.00},
{"name":"Sarah","sum":180.00}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/supervisors?select=supervisor:name,...processes(...process_costs(cost_sum:cost.sum()))&order=name" `shouldRespondWith`
[json|[
{"supervisor":"Jane","cost_sum":[null]},
{"supervisor":"John","cost_sum":[270.00]},
{"supervisor":"Mary","cost_sum":[220.00]},
{"supervisor":"Peter","cost_sum":[290.00]},
{"supervisor":"Sarah","cost_sum":[180.00]}]|]
{"supervisor":"Jane","cost_sum":null},
{"supervisor":"John","cost_sum":270.00},
{"supervisor":"Mary","cost_sum":220.00},
{"supervisor":"Peter","cost_sum":290.00},
{"supervisor":"Sarah","cost_sum":180.00}]|]
{ matchHeaders = [matchContentTypeJson] }
it "supports aggregates alongside the aggregates nested in to-one spread relationships" $ do
get "/supervisors?select=name,...processes(id.count(),...process_costs(cost.sum()))&order=name" `shouldRespondWith`
[json|[
{"name":"Jane","count":[0],"sum":[null]},
{"name":"John","count":[2],"sum":[270.00]},
{"name":"Mary","count":[2],"sum":[220.00]},
{"name":"Peter","count":[3],"sum":[290.00]},
{"name":"Sarah","count":[1],"sum":[180.00]}]|]
{"name":"Jane","count":0,"sum":null},
{"name":"John","count":2,"sum":270.00},
{"name":"Mary","count":2,"sum":220.00},
{"name":"Peter","count":3,"sum":290.00},
{"name":"Sarah","count":1,"sum":180.00}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/supervisors?select=supervisor:name,...processes(process_count:count(),...process_costs(cost_sum:cost.sum()))&order=name" `shouldRespondWith`
[json|[
{"supervisor":"Jane","process_count":[0],"cost_sum":[null]},
{"supervisor":"John","process_count":[2],"cost_sum":[270.00]},
{"supervisor":"Mary","process_count":[2],"cost_sum":[220.00]},
{"supervisor":"Peter","process_count":[3],"cost_sum":[290.00]},
{"supervisor":"Sarah","process_count":[1],"cost_sum":[180.00]}]|]
{"supervisor":"Jane","process_count":0,"cost_sum":null},
{"supervisor":"John","process_count":2,"cost_sum":270.00},
{"supervisor":"Mary","process_count":2,"cost_sum":220.00},
{"supervisor":"Peter","process_count":3,"cost_sum":290.00},
{"supervisor":"Sarah","process_count":1,"cost_sum":180.00}]|]
{ matchHeaders = [matchContentTypeJson] }
it "supports aggregates on nested relationships" $ do
get "/operators?select=name,...processes(id,...factories(...factory_buildings(size.sum())))&order=name" `shouldRespondWith`
[json|[
{"name":"Alfred","id":[6, 7],"sum":[[240], [240]]},
{"name":"Anne","id":[1, 2, 4],"sum":[[350], [350], [170]]},
{"name":"Jeff","id":[2, 3, 4, 6],"sum":[[350], [170], [170], [240]]},
{"name":"Alfred","id":[6, 7],"sum":[240, 240]},
{"name":"Anne","id":[1, 2, 4],"sum":[350, 350, 170]},
{"name":"Jeff","id":[2, 3, 4, 6],"sum":[350, 170, 170, 240]},
{"name":"Liz","id":[],"sum":[]},
{"name":"Louis","id":[1, 2],"sum":[[350], [350]]}]|]
{"name":"Louis","id":[1, 2],"sum":[350, 350]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/operators?select=name,...processes(process_id:id,...factories(...factory_buildings(factory_building_size_sum:size.sum())))&order=name" `shouldRespondWith`
[json|[
{"name":"Alfred","process_id":[6, 7],"factory_building_size_sum":[[240], [240]]},
{"name":"Anne","process_id":[1, 2, 4],"factory_building_size_sum":[[350], [350], [170]]},
{"name":"Jeff","process_id":[2, 3, 4, 6],"factory_building_size_sum":[[350], [170], [170], [240]]},
{"name":"Alfred","process_id":[6, 7],"factory_building_size_sum":[240, 240]},
{"name":"Anne","process_id":[1, 2, 4],"factory_building_size_sum":[350, 350, 170]},
{"name":"Jeff","process_id":[2, 3, 4, 6],"factory_building_size_sum":[350, 170, 170, 240]},
{"name":"Liz","process_id":[],"factory_building_size_sum":[]},
{"name":"Louis","process_id":[1, 2],"factory_building_size_sum":[[350], [350]]}]|]
{"name":"Louis","process_id":[1, 2],"factory_building_size_sum":[350, 350]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/operators?select=name,...processes(process_id:id,...factories(...factory_buildings(factory_building_size_sum:size.sum())))&processes.order=id.desc&order=name" `shouldRespondWith`
[json|[
{"name":"Alfred","process_id":[7, 6],"factory_building_size_sum":[240, 240]},
{"name":"Anne","process_id":[4, 2, 1],"factory_building_size_sum":[170, 350, 350]},
{"name":"Jeff","process_id":[6, 4, 3, 2],"factory_building_size_sum":[240, 170, 170, 350]},
{"name":"Liz","process_id":[],"factory_building_size_sum":[]},
{"name":"Louis","process_id":[2, 1],"factory_building_size_sum":[350, 350]}]|]
{ matchHeaders = [matchContentTypeJson] }

context "supports count() aggregate without specifying a field" $ do
context "one-to-many" $ do
it "works by itself in the embedded resource" $ do
get "/factories?select=name,...processes(count())&order=name" `shouldRespondWith`
[json|[
{"name":"Factory A","count":[2]},
{"name":"Factory B","count":[2]},
{"name":"Factory C","count":[4]},
{"name":"Factory D","count":[0]}]|]
{"name":"Factory A","count":2},
{"name":"Factory B","count":2},
{"name":"Factory C","count":4},
{"name":"Factory D","count":0}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/factories?select=factory:name,...processes(processes_count:count())&order=name" `shouldRespondWith`
[json|[
{"factory":"Factory A","processes_count":[2]},
{"factory":"Factory B","processes_count":[2]},
{"factory":"Factory C","processes_count":[4]},
{"factory":"Factory D","processes_count":[0]}]|]
{"factory":"Factory A","processes_count":2},
{"factory":"Factory B","processes_count":2},
{"factory":"Factory C","processes_count":4},
{"factory":"Factory D","processes_count":0}]|]
{ matchHeaders = [matchContentTypeJson] }
it "works alongside other columns in the embedded resource" $ do
get "/factories?select=name,...processes(category_id,count())&order=name" `shouldRespondWith`
Expand All @@ -413,36 +421,43 @@ allowed =
it "works on nested resources" $ do
get "/factories?select=id,...processes(name,...process_supervisor(count()))&order=id" `shouldRespondWith`
[json|[
{"id":1,"name":["Process A1", "Process A2"],"count":[[1], [1]]},
{"id":2,"name":["Process B1", "Process B2"],"count":[[2], [2]]},
{"id":3,"name":["Process C1", "Process C2", "Process XX", "Process YY"],"count":[[1], [1], [0], [0]]},
{"id":1,"name":["Process A1", "Process A2"],"count":[1, 1]},
{"id":2,"name":["Process B1", "Process B2"],"count":[2, 2]},
{"id":3,"name":["Process C1", "Process C2", "Process XX", "Process YY"],"count":[1, 1, 0, 0]},
{"id":4,"name":[],"count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/factories?select=id,...processes(process:name,...process_supervisor(ps_count:count()))&order=id" `shouldRespondWith`
[json|[
{"id":1,"process":["Process A1", "Process A2"],"ps_count":[[1], [1]]},
{"id":2,"process":["Process B1", "Process B2"],"ps_count":[[2], [2]]},
{"id":3,"process":["Process C1", "Process C2", "Process XX", "Process YY"],"ps_count":[[1], [1], [0], [0]]},
{"id":1,"process":["Process A1", "Process A2"],"ps_count":[1, 1]},
{"id":2,"process":["Process B1", "Process B2"],"ps_count":[2, 2]},
{"id":3,"process":["Process C1", "Process C2", "Process XX", "Process YY"],"ps_count":[1, 1, 0, 0]},
{"id":4,"process":[],"ps_count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/factories?select=id,...processes(process:name,...process_supervisor(ps_count:count()))&processes.order=name.desc&order=id" `shouldRespondWith`
[json|[
{"id":1,"process":["Process A2", "Process A1"],"ps_count":[1, 1]},
{"id":2,"process":["Process B2", "Process B1"],"ps_count":[2, 2]},
{"id":3,"process":["Process YY", "Process XX", "Process C2", "Process C1"],"ps_count":[0, 0, 1, 1]},
{"id":4,"process":[],"ps_count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }

context "many-to-many" $ do
it "works by itself in the embedded resource" $ do
get "/supervisors?select=name,...processes(count())&order=name" `shouldRespondWith`
[json|[
{"name":"Jane","count":[0]},
{"name":"John","count":[2]},
{"name":"Mary","count":[2]},
{"name":"Peter","count":[3]},
{"name":"Sarah","count":[1]}]|]
{"name":"Jane","count":0},
{"name":"John","count":2},
{"name":"Mary","count":2},
{"name":"Peter","count":3},
{"name":"Sarah","count":1}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/supervisors?select=supervisor:name,...processes(processes_count:count())&order=name" `shouldRespondWith`
[json|[
{"supervisor":"Jane","processes_count":[0]},
{"supervisor":"John","processes_count":[2]},
{"supervisor":"Mary","processes_count":[2]},
{"supervisor":"Peter","processes_count":[3]},
{"supervisor":"Sarah","processes_count":[1]}]|]
{"supervisor":"Jane","processes_count":0},
{"supervisor":"John","processes_count":2},
{"supervisor":"Mary","processes_count":2},
{"supervisor":"Peter","processes_count":3},
{"supervisor":"Sarah","processes_count":1}]|]
{ matchHeaders = [matchContentTypeJson] }
it "works alongside other columns in the embedded resource" $ do
get "/supervisors?select=name,...processes(category_id,count())&order=name" `shouldRespondWith`
Expand Down Expand Up @@ -472,18 +487,26 @@ allowed =
it "works on nested resources" $ do
get "/supervisors?select=id,...processes(name,...operators(count()))&order=id" `shouldRespondWith`
[json|[
{"id":1,"name":["Process A1", "Process B2"],"count":[[2], [2]]},
{"id":2,"name":["Process A2", "Process B2"],"count":[[3], [2]]},
{"id":3,"name":["Process B1", "Process C1", "Process C2"],"count":[[1], [0], [2]]},
{"id":4,"name":["Process B1"],"count":[[1]]},
{"id":1,"name":["Process A1", "Process B2"],"count":[2, 2]},
{"id":2,"name":["Process A2", "Process B2"],"count":[3, 2]},
{"id":3,"name":["Process B1", "Process C1", "Process C2"],"count":[1, 0, 2]},
{"id":4,"name":["Process B1"],"count":[1]},
{"id":5,"name":[],"count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/supervisors?select=supervisor:id,...processes(processes:name,...operators(operators_count:count()))&order=id" `shouldRespondWith`
[json|[
{"supervisor":1,"processes":["Process A1", "Process B2"],"operators_count":[[2], [2]]},
{"supervisor":2,"processes":["Process A2", "Process B2"],"operators_count":[[3], [2]]},
{"supervisor":3,"processes":["Process B1", "Process C1", "Process C2"],"operators_count":[[1], [0], [2]]},
{"supervisor":4,"processes":["Process B1"],"operators_count":[[1]]},
{"supervisor":1,"processes":["Process A1", "Process B2"],"operators_count":[2, 2]},
{"supervisor":2,"processes":["Process A2", "Process B2"],"operators_count":[3, 2]},
{"supervisor":3,"processes":["Process B1", "Process C1", "Process C2"],"operators_count":[1, 0, 2]},
{"supervisor":4,"processes":["Process B1"],"operators_count":[1]},
{"supervisor":5,"processes":[],"operators_count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }
get "/supervisors?select=supervisor:id,...processes(processes:name,...operators(operators_count:count()))&processes.order=name.desc&order=id" `shouldRespondWith`
[json|[
{"supervisor":1,"processes":["Process B2", "Process A1"],"operators_count":[2, 2]},
{"supervisor":2,"processes":["Process B2", "Process A2"],"operators_count":[2, 3]},
{"supervisor":3,"processes":["Process C2", "Process C1", "Process B1"],"operators_count":[2, 0, 1]},
{"supervisor":4,"processes":["Process B1"],"operators_count":[1]},
{"supervisor":5,"processes":[],"operators_count":[]}]|]
{ matchHeaders = [matchContentTypeJson] }

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