mongodb/mongoid · error · Mongoid::Errors::InvalidQuery

# argument must be an array: #

Error message

#{operator} argument must be an array: #{Errors::InvalidQuery.truncate_expr(op_expr)}

What it means

add_logical_operator_expression validates the pieces of a $and/$or/$nor clause: the operator must be one of those three strings and its value must be an Array of sub-expressions. A non-array value fails this guard with the truncated expression shown.

Solutions

1. Pass logical operator values as arrays of hashes, e.g. [ { a: 1 }, { b: 2 } ]
2. Build $or/$and via any_of/all so the shape is constructed correctly

When it happens

Trigger: Thrown at lib/mongoid/criteria/queryable/storable.rb:110 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mongodb/mongoid@0da0e23d71 (2026-08-23). Data as JSON: /api/errors/44bfb0300dd78645. Report an issue: GitHub.

Appendix: source

Thrown at lib/mongoid/criteria/queryable/storable.rb:110

        # Such simplification is also expected to have already been performed
        # by the upstream code.
        #
        # This method mutates the receiver.
        #
        # @param [ String ] operator The operator to add.
        # @param [ Array<Hash> ] op_expr Operator value to add.
        #
        # @return [ Storable ] self.
        def add_logical_operator_expression(operator, op_expr)
          raise ArgumentError, "Operator must be a string: #{operator}" unless operator.is_a?(String)

          unless %w[$and $nor $or].include?(operator)
            raise ArgumentError,
                  "This method only handles logical operators ($and, $nor, $or). Operator given: #{operator}"
          end

          unless op_expr.is_a?(Array)
            raise Errors::InvalidQuery, "#{operator} argument must be an array: #{Errors::InvalidQuery.truncate_expr(op_expr)}"
          end

          if selector.length == 1 && selector.keys.first == operator
            new_value = selector.values.first + op_expr
            selector.store(operator, new_value)
          elsif operator == '$and' || selector.empty?
            # $and can always be added to top level and it will be combined
            # with whatever other conditions exist.
            if current_value = selector[operator]
              new_value = current_value + op_expr
              selector.store(operator, new_value)
            else
              selector.store(operator, op_expr)
            end
          elsif selector[operator]
            # Other operators need to be added separately
            add_logical_operator_expression('$and', [ { operator => op_expr } ])
          else

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