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Rely on search_path (instead of "public") when deciding to fully-qualify view name #401

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@smudge smudge commented Jan 17, 2024

This should resolve the discrepancies in #327 and #325, and is in response to a behavior introduced in #152.

The heart of the issue is in how "public" was hardcoded in #152, because it assumes that "public" will be at the front of the search path (and is therefore the reason a view name should or should not be fully-qualified in schema.rb). But "public" being first in the search path is just a default configuration1 that can be overridden in a few different ways (e.g. schema_search_path in database.yml, or by setting it at the user/connection level, which some PAAS providers do).

In reality, PostgreSQL will create unqualified tables/views in current_schema(), and so we can rely on that to determine whether a view was created in the observer's default schema. (This is how Rails handles enum names when returning a list of all defined enums, a lookup case which otherwise appears very similar to what the scenic gem does for views.2)

This should resolve issues where laptop 1 and laptop 2 have different default schemas (or where different environments/deployments use different default schema names) but must share a schema.rb file; as long as the view is locally created in the (local's) default schema, the view will go unnamespaced in the generated schema file, but for anyone who writes a migration that explicitly creates a view in a non-default schema, that explicit schema name will survive the round-trip, as desired. Win-win 👍 .

Footnotes

  1. Technically "$user" (which resolves to the current PG user's name) is first by default, but that schema also doesn't exist by default, so current_schema() ends up being "public" by default.

  2. This was introduced in Support schemas in Postgresql enum_types rails/rails#45740

@@ -41,9 +42,9 @@ def views_from_postgres
end

def to_scenic_view(result)
namespace, viewname = result.values_at "namespace", "viewname"
namespace, viewname, current_schema = result.values_at "namespace", "viewname", "current_schema"
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Metrics/LineLength: Line is too long. [106/80]

view_definition = "SELECT 'needle'::text AS haystack"
Search.connection.execute "CREATE SCHEMA scenic; SET search_path TO scenic, public"
Search.connection.create_view :"scenic.searches", sql_definition: view_definition
Search.connection.create_view :"public.searches", sql_definition: view_definition
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Metrics/LineLength: Line is too long. [89/80]

it "dumps a create_view including namespace for a view in the database" do
view_definition = "SELECT 'needle'::text AS haystack"
Search.connection.execute "CREATE SCHEMA scenic; SET search_path TO scenic, public"
Search.connection.create_view :"scenic.searches", sql_definition: view_definition
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Metrics/LineLength: Line is too long. [89/80]

context 'when "public" is not the primary search path' do
it "dumps a create_view including namespace for a view in the database" do
view_definition = "SELECT 'needle'::text AS haystack"
Search.connection.execute "CREATE SCHEMA scenic; SET search_path TO scenic, public"
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Metrics/LineLength: Line is too long. [91/80]

Search.connection.create_view :"scenic.searches", sql_definition: view_definition
Search.connection.create_view :"public.searches", sql_definition: view_definition
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Metrics/LineLength: Line is too long. [87/80]

@@ -58,16 +58,38 @@ class SearchInAHaystack < ActiveRecord::Base
context "with views in non public schemas" do
it "dumps a create_view including namespace for a view in the database" do
view_definition = "SELECT 'needle'::text AS haystack"
Search.connection.execute "CREATE SCHEMA scenic; SET search_path TO scenic, public"
Search.connection.execute "CREATE SCHEMA scenic; SET search_path TO public, scenic"
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Metrics/LineLength: Line is too long. [89/80]

@smudge
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smudge commented Jan 17, 2024

Hmm, it seems the existing code was already in violation of the line length -- I assume hound only runs on the changed lines? 🤔

@calebhearth
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calebhearth commented Jan 17, 2024 via email

@smudge smudge force-pushed the avoid-hardcoding-public branch from bb11555 to 6f15271 Compare January 19, 2024 22:28
@smudge
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smudge commented Jan 19, 2024

(rebased due to file conflicts)

@teoljungberg
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I'd be interesting in hearing what you reason about this @calebhearth - as @smudge has laid forth a similar proposal in fx (teoljungberg/fx#140). I'd like if Scenic and fx handled this the same way.

@calebhearth calebhearth added this to the 2.0 milestone Jan 20, 2024
@derekprior
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My thought right now is that adding specific handling of schema to scenic was a mistake and that we should remove it. It has led to a number of issues raised by users. I think it makes sense to behave exactly as rails behaves with tables. If you want to store views in a different schema then you need a different search path. I think #402 would make that something that could be done rather trivially and in line with Rails conventions.

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4 participants