Add support for hash and url configs to be used in connected_to #34196

gmcgibbon · 2018-10-11T22:02:38Z

Summary

I noticed when using the new connection switching API, if I use a string database name, it bubbles down to this connection resolution method which thinks strings are database URLs. Do we want to support URLs, or is this acceptable behaviour? If not, we should make DatabaseConfig#spec_name return a symbol instead of a string.

gmcgibbon · 2018-10-11T22:03:08Z

r? @eileencodes
cc @rafaelfranca

eileencodes · 2018-10-11T22:23:24Z

Right now connects_to wraps around establish_connection so it should behave the same exact way.

>> ActiveRecord::Base.establish_connection "primary"
ActiveRecord::AdapterNotSpecified: database configuration does not specify adapter
	from (irb):14

>> ActiveRecord::Base.connects_to database: { :writing => "primary" }
ActiveRecord::AdapterNotSpecified: database configuration does not specify adapter
	from (irb):15

To me a string that's not a URL causing an error is the correct behavior. I do think however this error message could be improved to note it expected a database URL instead.

gmcgibbon · 2018-10-11T22:52:00Z

Ok, I assumed it was different because you can't currently use a connection hash because of this to_sym call. What do you think of DatabaseConfig#spec_name returning a symbol then? I can also improve the error in another PR.

eileencodes · 2018-10-12T11:43:21Z

Ohhhh I see - I was thinking about connects_to. Yes in that case we should remove the to_sym call in connected_to. That was a mistake on my part. Can you update this PR to remove that and add a test for a URL configuration? Thanks!

eileencodes · 2018-10-12T11:49:59Z

The underlying problem is that there are a billion ways to make a configuration and connect to the database. Take a look at this test https://github.com/rails/rails/blob/master/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb and you'll get an idea of some of the possible scenarios. We may eventually want to say some of these are not going to be possible with a multi-db application but I don't think we're there yet. For example, I'm not sure how a DATABASE_URL would work with multiple databases - since you can only pass one at a time.

gmcgibbon · 2018-10-12T15:08:13Z

Done! I added a test for both hash configs and URLs since they both fail on master.

gmcgibbon · 2018-10-12T15:10:34Z

activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb

+
+          ActiveRecord::Base.connected_to(database: config) do
+            handler = ActiveRecord::Base.connection_handler
+            assert_equal handler, ActiveRecord::Base.connection_handlers[config]


I'm not sure how I feel about this. Should we try to lookup the config to store the handler with a symbol key and fallback to this behaviour if its not mentioned in database.yml?

Oh 💩 it just occurred to me this isn't going to work. It's fine if it's a symbol but what would the handler be if it was a url? We definitely don't want the handler to be postgres://blah so I think we need to change connects to to take a role and a database at the same time and only if it's a symbol use the database name as a handler. Thoughts?

Yeah, I think if we always lookup handlers using symbols, that makes the most sense. Does it make sense to always use roles for handler lookup or do we need to still try using the database spec/env/config/url/??? for legacy support?

We need the handler/role for when you're connected already and we need the database for connecting to a database that your model doesn't always want to be connected to (for example, readonly_slow). Role should always be symbol. I'm not sure what legacy support we would need? This is a new method so we can change it until 6 is released.

I've been thinking about this and I think we should either accept a symbol or a hash for the database option. If you need to pass a string then you need to also pass a role / name / handler with it.

ActiveRecord::Base.connected_to(database: { my_url_db: "postgres://blah" }) do # do something with this db end

Otherwise a symbol is expected.

I changed the logic around to use database if its a symbol or role if it isn't. That should solve the issue AFAICT.

I've been thinking about this and I think we should either accept a symbol or a hash for the database option. If you need to pass a string then you need to also pass a role / name / handler with it.

I've refactored the method to behave this way for both URLs and config hashes. WDYT?

eileencodes · 2018-10-26T13:02:21Z

activerecord/test/cases/connection_adapters/connection_handlers_multi_db_test.rb

+
+          ActiveRecord::Base.connected_to(database: config) do
+            handler = ActiveRecord::Base.connection_handler
+            assert_equal handler, ActiveRecord::Base.connection_handlers[config]


We need the handler/role for when you're connected already and we need the database for connecting to a database that your model doesn't always want to be connected to (for example, readonly_slow). Role should always be symbol. I'm not sure what legacy support we would need? This is a new method so we can change it until 6 is released.

I've been thinking about this and I think we should either accept a symbol or a hash for the database option. If you need to pass a string then you need to also pass a role / name / handler with it.

ActiveRecord::Base.connected_to(database: { my_url_db: "postgres://blah" }) do # do something with this db end

Otherwise a symbol is expected.

eileencodes · 2018-10-26T19:04:09Z

activerecord/lib/active_record/connection_handling.rb

        config_hash = resolve_config_for_connection(database)
-        handler = lookup_connection_handler(database.to_sym)
+        handler = lookup_connection_handler(hanlder_key)


You have a typo in handler 😄

🤦‍♂️

Add support for hash and url configs in database hash of `ActiveRecord::Base.connected_to`.

eileencodes · 2018-10-30T12:56:43Z

This looks great! Thank you!

Caused at #34196.

bogdanvlviv · 2018-11-01T21:15:20Z

activerecord/CHANGELOG.md

@@ -1,3 +1,18 @@
+*   Add support for hash and url configs in database hash of `ActiveRecord::Base.connected_to`.


Great addition. Thank you! Just want to note that we don't add changelog entries about complementing features that haven't been released.

rails-bot bot added the activerecord label Oct 11, 2018

rails-bot assigned eileencodes Oct 11, 2018

gmcgibbon force-pushed the connection_switch_string_name branch from 8a8d8a4 to cd80e72 Compare October 11, 2018 22:06

gmcgibbon force-pushed the connection_switch_string_name branch from cd80e72 to 634f546 Compare October 12, 2018 15:06

gmcgibbon changed the title ~~Allow connection switching with string database names~~ Add support for hash and url configs to be used in connected_to Oct 12, 2018

gmcgibbon commented Oct 12, 2018

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gmcgibbon force-pushed the connection_switch_string_name branch 4 times, most recently from 195dc38 to 8ad5850 Compare October 26, 2018 18:10

eileencodes reviewed Oct 26, 2018

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gmcgibbon force-pushed the connection_switch_string_name branch 3 times, most recently from c2d0a58 to d468d48 Compare October 26, 2018 20:26

Add support for hash and url configs in connected_to

abf5184

Add support for hash and url configs in database hash of `ActiveRecord::Base.connected_to`.

gmcgibbon force-pushed the connection_switch_string_name branch from d468d48 to abf5184 Compare October 26, 2018 20:28

eileencodes merged commit 6889e72 into rails:master Oct 30, 2018

kamipo added a commit that referenced this pull request Oct 31, 2018

Fix "warning: shadowing outer local variable - role"

b86c2a6

Caused at #34196.

bogdanvlviv reviewed Nov 1, 2018

View reviewed changes

gmcgibbon deleted the connection_switch_string_name branch November 1, 2018 21:33

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Add support for hash and url configs to be used in connected_to #34196

Add support for hash and url configs to be used in connected_to #34196

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eileencodes commented Oct 30, 2018

bogdanvlviv Nov 1, 2018

		@@ -1,3 +1,18 @@
		* Add support for hash and url configs in database hash of `ActiveRecord::Base.connected_to`.

Add support for hash and url configs to be used in connected_to #34196

Add support for hash and url configs to be used in connected_to #34196

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gmcgibbon commented Oct 11, 2018 • edited Loading

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eileencodes commented Oct 30, 2018

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