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Fix undefined method 'join' for an instance of String on hover #645

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Fix undefined method 'join' for an instance of String on hover #645

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97e0be8
create index to reproduce issue
cpgo Aug 16, 2025
007733d
handle when index[:columns] is Array or String
cpgo Aug 16, 2025
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10 changes: 9 additions & 1 deletion lib/ruby_lsp/ruby_lsp_rails/hover.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,15 @@ def generate_column_content(name)
@response_builder.push(
model[:indexes].map do |index|
uniqueness = index[:unique] ? " (unique)" : ""
"- **#{index[:name]}** (#{index[:columns].join(",")})#{uniqueness}"
columns = case index[:columns]
when Array
index[:columns].join(",")
when String
index[:columns]
else
index[:name]
end
"- **#{index[:name]}** (#{columns})#{uniqueness}"
Comment on lines +100 to +108
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Just trying to understand the different scenarios here. Array is the case when we have multiple columns associated to the index.

When is it a string? And when would it not be either (when do we reach the else block)?

In the case of the else block, we're essentially showing the index's name twice on the hover, which may not be super useful. Is there any other information for that scenario that we could show?

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@cpgo cpgo Aug 18, 2025 •
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I guess the else case is not really necessary, I just added because I'm not super familiar with the possible values here.

When is it a string?

I noticed on one of my applications when indexes contained "complex" sql processing like

execute "CREATE UNIQUE INDEX users_unique_complex ON users (COALESCE(country_id, 0), ltrim(first_name));"

In those cases .join was called on the whole index expression CREATE UNIQUE INDEX... instead of the array of columns

end.join("\n"),
category: :documentation,
)
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5 changes: 5 additions & 0 deletions test/dummy/db/migrate/20250816140957_add_complex_index_to_users.rb
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@@ -0,0 +1,5 @@
class AddComplexIndexToUsers < ActiveRecord::Migration[8.0]
def change
execute "CREATE UNIQUE INDEX users_unique_complex ON users (COALESCE(country_id, 0), ltrim(first_name));"
end
end
3 changes: 2 additions & 1 deletion test/dummy/db/schema.rb
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Expand Up @@ -10,7 +10,7 @@
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema[8.0].define(version: 2024_10_25_225348) do
ActiveRecord::Schema[8.0].define(version: 2025_08_16_140957) do
create_table "composite_primary_keys", primary_key: ["order_id", "product_id"], force: :cascade do |t|
t.integer "order_id"
t.integer "product_id"
Expand Down Expand Up @@ -55,6 +55,7 @@
t.datetime "updated_at", null: false
t.integer "country_id", null: false
t.boolean "active", default: true, null: false
t.index "COALESCE(country_id, 0), ltrim(first_name)", name: "users_unique_complex", unique: true
t.index ["country_id"], name: "index_users_on_country_id"
end

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63 changes: 63 additions & 0 deletions test/ruby_lsp_rails/hover_test.rb
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Expand Up @@ -321,6 +321,69 @@ class Bar < ApplicationRecord
CONTENT
end

test "handles complex indexes with expressions" do
expected_response = {
schema_file: "#{dummy_root}/db/schema.rb",
columns: [
["id", "integer", nil, false],
["first_name", "string", "", true],
["last_name", "string", nil, true],
["age", "integer", "0", true],
["created_at", "datetime", nil, false],
["updated_at", "datetime", nil, false],
["country_id", "integer", nil, false],
["active", "boolean", "true", false],
],
primary_keys: ["id"],
foreign_keys: ["country_id"],
indexes: [
{ name: "index_users_on_country_id", columns: ["country_id"], unique: false },
{ name: "users_unique_complex", columns: "COALESCE(country_id, 0), ltrim(first_name)", unique: true }
],
}

RunnerClient.any_instance.stubs(model: expected_response)

response = hover_on_source(<<~RUBY, { line: 3, character: 0 })
class User < ApplicationRecord
end

User
RUBY

assert_equal(<<~CONTENT.chomp, response.contents.value)
```ruby
User
```

**Definitions**: [fake.rb](file:///fake.rb#L1,1-2,4)


[Schema](#{URI::Generic.from_path(path: dummy_root + "/db/schema.rb")})

### Columns
- **id**: integer (PK)

- **first_name**: string - default: ""

- **last_name**: string

- **age**: integer - default: 0

- **created_at**: datetime - not null

- **updated_at**: datetime - not null

- **country_id**: integer (FK) - not null

- **active**: boolean - default: true - not null

### Indexes
- **index_users_on_country_id** (country_id)
- **users_unique_complex** (COALESCE(country_id, 0), ltrim(first_name)) (unique)
CONTENT
end

private

def hover_on_source(source, position)
Expand Down
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