Merge pull request #1114 from suketa/issue922

Issue922 sample script

Author: suketa

sample/issue922.rb

@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+require 'duckdb'
+require 'polars-df'
+
+df = Polars::DataFrame.new(
+  {
+    a: [1, 2, 3],
+    b: %w[one two three]
+  }
+)
+
+module DuckDB
+  class TableFunction
+    @table_adapters = {}
+    class << self
+      def add_table_adapter(klass, adapter)
+        @table_adapters[klass] = adapter
+      end
+
+      def table_adapter_for(klass)
+        @table_adapters[klass]
+      end
+    end
+  end
+
+  class Connection
+    def create_table_function(object, name)
+      adapter = TableFunction.table_adapter_for(object.class)
+      raise ArgumentError, "No table adapter registered for #{object.class}" if adapter.nil?
+
+      tf = adapter.call(object, name)
+      register_table_function(tf)
+    end
+  end
+
+  module Polars
+    module DataFrame
+      class TableAdapter
+        def call(df, name) # rubocop:disable Metrics/MethodLength, Naming/MethodParameterName
+          columns = df.columns.each_with_object({}) { |header, hash| hash[header] = LogicalType::VARCHAR }
+          counter = 0
+          height = df.height
+          width = df.columns.length
+
+          DuckDB::TableFunction.create(
+            name:,
+            columns:
+          ) do |_func_info, output|
+            if counter < height
+              width.times do |index|
+                output.set_value(index, 0, df[counter, index])
+              end
+              counter += 1
+              1
+            else
+              counter = 0
+              0
+            end
+          end
+        end
+      end
+    end
+  end
+  TableFunction.add_table_adapter(::Polars::DataFrame, DuckDB::Polars::DataFrame::TableAdapter.new)
+end
+
+db = DuckDB::Database.open
+
+con = db.connect
+con.query('SET threads=1')
+con.create_table_function(df, 'polars_df')
+result = con.query('SELECT * FROM polars_df()').to_a
+p result
+puts result.first.first == '1'
+
+con.close
+db.close