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Contents
module Polars
module IO
# Read a SQL query into a DataFrame.
#
# @param query [Object]
# ActiveRecord::Relation or ActiveRecord::Result.
# @param schema_overrides [Hash]
# A hash mapping column names to dtypes, used to override the schema
# inferred from the query.
#
# @return [DataFrame]
def read_database(query, schema_overrides: nil)
if !defined?(ActiveRecord)
raise Error, "Active Record not available"
end
result =
if query.is_a?(ActiveRecord::Result)
query
elsif query.is_a?(ActiveRecord::Relation)
query.connection.select_all(query.to_sql)
elsif query.is_a?(::String)
ActiveRecord::Base.connection.select_all(query)
else
raise ArgumentError, "Expected ActiveRecord::Relation, ActiveRecord::Result, or String"
end
data = {}
schema_overrides = (schema_overrides || {}).transform_keys(&:to_s)
result.columns.each_with_index do |k, i|
column_type = result.column_types[i]
data[k] =
if column_type
result.rows.map { |r| column_type.deserialize(r[i]) }
else
result.rows.map { |r| r[i] }
end
polars_type =
case column_type&.type
when :binary
Binary
when :boolean
Boolean
when :date
Date
when :datetime, :timestamp
Datetime
when :decimal
Decimal
when :float
Float64
when :integer
Int64
when :string, :text
String
when :time
Time
# TODO fix issue with null
# when :json, :jsonb
# Struct
end
schema_overrides[k] ||= polars_type if polars_type
end
DataFrame.new(data, schema_overrides: schema_overrides)
end
alias_method :read_sql, :read_database
end
end
Version data entries
28 entries across 28 versions & 1 rubygems