Support JSON type

.docker/clickhouse/users.xml

@@ -4,6 +4,7 @@
   <profiles>
     <default>
       <load_balancing>random</load_balancing>
+      <enable_json_type>1</enable_json_type>
     </default>
   </profiles>
 
@@ -31,4 +32,4 @@
       </interval>
     </default>
   </quotas>
-</clickhouse>
+</clickhouse>

README.md

@@ -212,6 +212,7 @@ false`. The default integer is `UInt32`
 | UInt256         |                   0 to ...                   |                 8+ |
 | Array           |                     ...                      |                ... |
 | Map             |                     ...                      |                ... |
+| JSON            |                     ...                      |                ... |
 
 Example:
 

lib/active_record/connection_adapters/clickhouse_adapter.rb

@@ -110,6 +110,8 @@ class ClickhouseAdapter < AbstractAdapter
         uint64: { name: 'UInt64' },
         # uint128: { name: 'UInt128' }, not yet implemented in clickhouse
         uint256: { name: 'UInt256' },
+
+        json: { name: 'JSON' },
       }.freeze
 
       include Clickhouse::SchemaStatements
@@ -242,6 +244,8 @@ def initialize_type_map(m) # :nodoc:
           m.register_type(%r(Map)) do |sql_type|
             Clickhouse::OID::Map.new(sql_type)
           end
+
+          m.register_type %r(JSON)i, Type::Json.new
         end
       end
 

spec/fixtures/migrations/add_sample_data/1_create_sample_table.rb

@@ -12,6 +12,7 @@ def up
       t.string :byte_array
       t.uuid :relation_uuid
       t.decimal :decimal_value, precision: 38, scale: 16
+      t.json :json_value, null: false, default: {}
     end
   end
 end

spec/single/model_spec.rb

@@ -158,6 +158,28 @@ class ModelPk < ActiveRecord::Base
       end
     end
 
+    describe 'JSON column type' do
+      let(:json) { { 'key' => 'value' } }
+      let!(:record1) { Model.create!(event_name: 'some event', json_value: json) }
+
+      it 'is mapped to :json' do
+        type = Model.columns_hash['json_value'].type
+        expect(type).to eq(:json)
+      end
+
+      it 'keeps JSON value' do
+        expect(Model.first.json_value).to eq(json)
+      end
+
+      context 'when the JSON column is complex' do
+        let(:json) { { 'key' => { 'nested_key' => 'value', 'another_key' => ['something'] } } }
+
+        it 'keeps JSON value' do
+          expect(Model.first.json_value).to eq(json)
+        end
+      end
+    end
+
     describe 'boolean column type' do
       let!(:record1) { Model.create!(event_name: 'some event', event_value: 1, date: date) }