How to escape the ? (question mark) operator to query Postgresql JSONB type in Rails

问题

I'm working with Rails 4.2 and Postgres 9.4 to try out the new JSONB data type. One of the JSONB columns in my database holds an array, and I want to be able to query for records where this array contains a certain value. I figured out how to do this using the new JSONB "question mark" ("contains") operator, as documented here: http://www.postgresql.org/docs/9.4/static/functions-json.html

So in raw SQL I can get this to work as in this example:

SELECT * FROM people WHERE roles ? '32486d83-4a38-42ba-afdb-f77ca40ea1fc';

But I can't see any way to do this query from within Rails via ActiveRecord. I've tried doing a raw query using the "where" method, as follows:

Person.where("roles ? ?", "32486d83-4a38-42ba-afdb-f77ca40ea1fc")

But since the question mark is a special character used to replace parameters, I get this error:

ActiveRecord::PreparedStatementInvalid: wrong number of bind variables (1 for 2) in: roles ? ?

I guess I need a way to escape the "?" character since I want it to pass through literally. I've tried \? and ?? with no luck. Any help is appreciated!

回答1:

You should call this as below :

Person.where("roles ? :name", name: "32486d83-4a38-42ba-afdb-f77ca40ea1fc")

回答2:

A workaround. Run this query to find out what function your operator maps to:

SELECT 
  oprname, 
  oprcode || '(' || format_type(oprleft,  NULL::integer) || ', ' 
                 || format_type(oprright, NULL::integer) || ')' AS function
FROM pg_operator 
WHERE oprname = '?';

It yields

oprname  function
?        jsonb_exists(jsonb, text)
?        exist(hstore, text)

Now use the function instead of the operator in your query:

Person.where("jsonb_exists(roles, ?)", "32486d83-4a38-42ba-afdb-f77ca40ea1fc")

来源：https://stackoverflow.com/questions/30629076/how-to-escape-the-question-mark-operator-to-query-postgresql-jsonb-type-in-r