feat: Allow backslash escaping inside double quotes

Examples:

- ?col=in.("Double\"Quote")
- ?col=in.("Back\\slash")

Backslashed chars get passed as is

- ?col=in.("\a\b\c") = ?col=in.(abc)

CHANGELOG.md

@@ -13,6 +13,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
    + Enables calling a function with a single json parameter without using `Prefer: params=single-object`
    + Enables uploading bytea to a function with `Content-Type: application/octet-stream`
    + Enables uploading raw text to a function with `Content-Type: text/plain`
+- #1938, Allow escaping inside double quotes with a backslash, e.g. `?col=in.("Double\"Quote")`, `?col=in.("Back\\slash")` - @steve-chavez
 
 ### Fixed
 

src/PostgREST/Request/Parsers.hs

@@ -207,7 +207,9 @@ pListElement :: Parser Text
 pListElement = try (pQuotedValue <* notFollowedBy (noneOf ",)")) <|> (toS <$> many (noneOf ",)"))
 
 pQuotedValue :: Parser Text
-pQuotedValue = toS <$> (char '"' *> many (noneOf "\"") <* char '"')
+pQuotedValue = toS <$> (char '"' *> many pCharsOrSlashed <* char '"')
+  where
+    pCharsOrSlashed = noneOf "\\\"" <|> (char '\\' *> anyChar)
 
 pDelimiter :: Parser Char
 pDelimiter = char '.' <?> "delimiter (.)"

test/Feature/QuerySpec.hs

@@ -953,6 +953,25 @@ spec actualPgVersion = do
         [json| [{"name":"Double O Seven(007)"}] |]
         { matchHeaders = [matchContentTypeJson] }
 
+    context "escaped chars" $ do
+      it "accepts escaped double quotes" $
+        get "/w_or_wo_comma_names?name=in.(\"Double\\\"Quote\\\"McGraw\\\"\")" `shouldRespondWith`
+          [json| [ { "name": "Double\"Quote\"McGraw\"" } ] |]
+          { matchHeaders = [matchContentTypeJson] }
+
+      it "accepts escaped backslashes" $ do
+        get "/w_or_wo_comma_names?name=in.(\"\\\\\")" `shouldRespondWith`
+          [json| [{ "name": "\\" }] |]
+          { matchHeaders = [matchContentTypeJson] }
+        get "/w_or_wo_comma_names?name=in.(\"/\\\\Slash/\\\\Beast/\\\\\")" `shouldRespondWith`
+          [json| [ { "name": "/\\Slash/\\Beast/\\" } ] |]
+          { matchHeaders = [matchContentTypeJson] }
+
+      it "passes any escaped char as the same char" $
+        get "/w_or_wo_comma_names?name=in.(\"D\\a\\vid W\\h\\ite\")" `shouldRespondWith`
+          [json| [{ "name": "David White" }] |]
+          { matchHeaders = [matchContentTypeJson] }
+
   describe "IN values without quotes" $ do
     it "accepts single double quotes as values" $ do
       get "/w_or_wo_comma_names?name=in.(\")" `shouldRespondWith`