Reusing the same parameter in WHERE fails to parse

[typeofweb]

The problem

Using the same argument in 2 places inside a WHERE fails to parse. For example:

/*
  @name FindAllQuestions1
*/
SELECT id FROM "Question" WHERE ( ( :category IS NULL ) OR ( "_categoryId" = :category ) );

Results in:

Error in query. Details: {
  errorCode: 'scanner_yyerror',
  hint: undefined,
  message: 'syntax error at or near ":"',
  position: '37'
}

However, if I keep the query almost the same but just remove one :category, it works:

/*
  @name FindAllQuestions2
*/
SELECT id FROM "Question" WHERE ( ( 123 IS NULL ) OR ( "_categoryId" = :category ) );

(No errors)

/*
  @name FindAllQuestions3
*/
SELECT id FROM "Question" WHERE ( ( :category IS NULL ) OR ( "_categoryId" = 'foo' ) );

(could not determine data type of parameter $1, which makes sense and it parsed just fine)

DB Logs

Looking at my database logs I can't help but notice that the first usage of the parameter was not replaced by $1:

db_1  | 2020-06-05 13:47:55.249 UTC [2572] ERROR:  syntax error at or near ":" at character 37
db_1  | 2020-06-05 13:47:55.249 UTC [2572] STATEMENT:  SELECT id FROM "Question" WHERE ( ( :category IS NULL ) OR ( "_categoryId" = $1 ) )