---
title: "Rails 6 deprecates where.not as NOR & Rails 6.1 as NAND"
description:
  "Rails 6 adds a deprecation warning for where.not as NOR and will change in
  Rails 6.1 to NAND"
canonical_url: "https://www.bigbinary.com/blog/rails-6-deprecates-where-not-working-as-nor-and-will-change-to-nand-in-rails-6-1"
markdown_url: "https://www.bigbinary.com/blog/rails-6-deprecates-where-not-working-as-nor-and-will-change-to-nand-in-rails-6-1.md"
---

# Rails 6 deprecates where.not as NOR & Rails 6.1 as NAND

Rails 6 adds a deprecation warning for where.not as NOR and will change in Rails
6.1 to NAND

- Author: Taha Husain
- Published: July 31, 2019
- Categories: Rails 6, Rails

A notable deprecation warning has been added in Rails 6 when using `where.not`
with multiple attributes.

Before Rails 6, if we use `where.not` with multiple attributes, it applies
logical _NOR (NOT(A) AND NOT(B))_ in _WHERE_ clause of the query. This does not
always work as expected.

Let's look at an example to understand this better.

We have `Post` model with a polymorphic association.

##### Rails 5.2

```ruby

>> Post.all
=> #<ActiveRecord::Relation [
#<Post id: 1, title: "First Post", source_type: "Feed", source_id: 100>,
#<Post id: 2, title: "Second Post", source_type: "Feed", source_id: 101>]>

>> Post.where(source_type: "Feed", source_id: 100)
=> #<ActiveRecord::Relation [#<Post id: 1, title: "First Post", source_type: "Feed", source_id: 100>]>

>> Post.where.not(source_type: "Feed", source_id: 100)
=> #<ActiveRecord::Relation []>

```

In the last query, we expect ActiveRecord to fetch one record.

Let's check SQL generated for the above case.

```ruby

>> Post.where.not(source_type: "Feed", source_id: 100).to_sql

=> SELECT "posts".* FROM "posts" WHERE "posts"."source_type" != 'Feed' AND "posts"."source_id" != 100

```

`where.not` applies _AND_ to the negation of `source_type` and `source_id`, and
fails to fetch expected records.

In such cases, correct implementation of `where.not` would be logical _NAND_
_(NOT(A) OR NOT(B))_.

Let us query `posts` table using NAND this time.

```ruby

>> Post.where("source_type != 'Feed' OR source_id != 100")

   SELECT "posts".* FROM "posts" WHERE (source_type != 'Feed' OR source_id != 100)

=> #<ActiveRecord::Relation [#<Post id: 2, title: "Second Post", source_type: "Feed", source_id: 101>]>

```

Above query works as expected and returns one record. Rails 6.1 will change
`where.not` working to NAND similar to the above query.

##### Rails 6.0.0.rc1

```ruby

>> Post.where.not(source_type: "Feed", source_id: 100)

DEPRECATION WARNING: NOT conditions will no longer behave as NOR in Rails 6.1. To continue using NOR conditions, NOT each conditions manually (`.where.not(:source_type => ...).where.not(:source_id => ...)`). (called from irb_binding at (irb):1)

=> #<ActiveRecord::Relation []>

```

It is well mentioned in deprecation warning that if we wish to use _NOR_
condition with multiple attributes, we can chain multiple `where.not` using a
single predicate.

```ruby

>> Post.where.not(source_type: "Feed").where.not(source_id: 100)

```

Here's the relevant [discussion](https://github.com/rails/rails/issues/31209)
and [pull request](https://github.com/rails/rails/pull/36029) for this change.

## Links

- [Human page](https://www.bigbinary.com/blog/rails-6-deprecates-where-not-working-as-nor-and-will-change-to-nand-in-rails-6-1)