feat: allow aliases in spread embeddings

Author: laurenceisla

src/PostgREST/ApiRequest/QueryParams.hs

@@ -291,7 +291,7 @@ pTreePath = do
 -- Right [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []},Node {rootLabel = SelectRelation {selRelation = "client", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []},Node {rootLabel = SelectRelation {selRelation = "nested", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []}]}]}]
 --
 -- >>> P.parse pFieldForest "" "*,...client(*),other(*)"
--- Right [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []},Node {rootLabel = SpreadRelation {selRelation = "client", selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []}]},Node {rootLabel = SelectRelation {selRelation = "other", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []}]}]
+-- Right [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []},Node {rootLabel = SpreadRelation {selRelation = "client", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []}]},Node {rootLabel = SelectRelation {selRelation = "other", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing}, subForest = [Node {rootLabel = SelectField {selField = ("*",[]), selAggregateFunction = Nothing, selAggregateCast = Nothing, selCast = Nothing, selAlias = Nothing}, subForest = []}]}]
 --
 -- >>> P.parse pFieldForest "" ""
 -- Right []
@@ -555,10 +555,13 @@ pFieldSelect = lexeme $ try (do
 -- Parse spread relations in select
 --
 -- >>> P.parse pSpreadRelationSelect "" "...rel(*)"
--- Right (SpreadRelation {selRelation = "rel", selHint = Nothing, selJoinType = Nothing})
+-- Right (SpreadRelation {selRelation = "rel", selAlias = Nothing, selHint = Nothing, selJoinType = Nothing})
+--
+-- >>> P.parse pSpreadRelationSelect "" "...alias:rel(*)"
+-- Right (SpreadRelation {selRelation = "rel", selAlias = Just "alias", selHint = Nothing, selJoinType = Nothing})
 --
 -- >>> P.parse pSpreadRelationSelect "" "...rel!hint!inner(*)"
--- Right (SpreadRelation {selRelation = "rel", selHint = Just "hint", selJoinType = Just JTInner})
+-- Right (SpreadRelation {selRelation = "rel", selAlias = Nothing, selHint = Just "hint", selJoinType = Just JTInner})
 --
 -- >>> P.parse pSpreadRelationSelect "" "rel(*)"
 -- Left (line 1, column 1):
@@ -575,10 +578,11 @@ pFieldSelect = lexeme $ try (do
 -- unexpected '>'
 pSpreadRelationSelect :: Parser SelectItem
 pSpreadRelationSelect = lexeme $ do
-    name <- string "..." >> pFieldName
+    alias <- string "..." >> optionMaybe ( try(pFieldName <* aliasSeparator) )
+    name <- pFieldName
     (hint, jType) <- pEmbedParams
     try (void $ lookAhead (string "("))
-    return $ SpreadRelation name hint jType
+    return $ SpreadRelation name alias hint jType
 
 pEmbedParams :: Parser (Maybe Hint, Maybe JoinType)
 pEmbedParams = do

src/PostgREST/ApiRequest/Types.hs

@@ -64,6 +64,7 @@ data SelectItem
 -- | The value in `/tbl?select=...another_tbl(*)`
   | SpreadRelation
     { selRelation :: FieldName
+    , selAlias    :: Maybe Alias
     , selHint     :: Maybe Hint
     , selJoinType :: Maybe JoinType
     }

src/PostgREST/Plan.hs

@@ -367,7 +367,7 @@ initReadRequest ctx@ResolverContext{qi=QualifiedIdentifier{..}} =
         SpreadRelation{..} ->
           Node q $
             foldr (treeEntry nxtDepth)
-            (Node defReadPlan{from=QualifiedIdentifier qiSchema selRelation, relName=selRelation, relHint=selHint, relJoinType=selJoinType, depth=nxtDepth, relIsSpread=True} [])
+            (Node defReadPlan{from=QualifiedIdentifier qiSchema selRelation, relName=selRelation, relAlias=selAlias, relHint=selHint, relJoinType=selJoinType, depth=nxtDepth, relIsSpread=True} [])
             fldForest:rForest
         SelectField{..} ->
           Node q{select=CoercibleSelectField (resolveOutputField ctx{qi=from q} selField) selAggregateFunction selAggregateCast selCast selAlias:select q} rForest