generate_aggregation_code: Generate data.table Aggregation Code from Metadata

In DBmaps: A Metadata-Driven Framework for Streamlining Database Joins

Generate data.table Aggregation Code from Metadata

Description

Reads metadata from a master data.table and generates executable data.table code strings for performing aggregations.

Usage

generate_aggregation_code(table_name_filter, metadata_dt)

Arguments

table_name_filter	Character string, the name of the table for which to generate aggregation code.
metadata_dt	A data.table containing the master metadata, created by calling table_info() for multiple tables and combining them.

Value

A named character vector where each element is a runnable data.table code string, and the names correspond to the grouping variables.

Examples

# First, create some metadata
customers_info <- table_info(
  table_name = "customers",
  source_identifier = "customers.csv",
  identifier_columns = "customer_id",
  key_outcome_specs = list(
    list(OutcomeName = "CustomerCount", ValueExpression = 1, AggregationMethods = list(
      list(AggregatedName = "CountByRegion", AggregationFunction = "sum",
           GroupingVariables = "region")
    ))
))

transactions_info <- table_info(
  table_name = "transactions",
  source_identifier = "transactions.csv",
  identifier_columns = "transaction_id",
  key_outcome_specs = list(
    list(OutcomeName = "Revenue", ValueExpression = quote(amount), AggregationMethods = list(
      list(AggregatedName = "RevenueByCustomer", AggregationFunction = "sum",
           GroupingVariables = "customer_id"),
      list(AggregatedName = "RevenueByProduct", AggregationFunction = "sum",
           GroupingVariables = "product_id")
    )),
    list(OutcomeName = "Transactions", ValueExpression = 1, AggregationMethods = list(
      list(AggregatedName = "TransactionsByCustomer", AggregationFunction = "sum",
           GroupingVariables = "customer_id")
    ))
))

master_metadata <- data.table::rbindlist(list(customers_info, transactions_info))

# Now, generate the code for the "transactions" table
generated_code <- generate_aggregation_code("transactions", master_metadata)
print(generated_code)

# To demonstrate execution:
# 1. Create the sample data
transactions <- data.table::data.table(
  transaction_id = c("T001", "T002", "T003"),
  customer_id = c("C001", "C002", "C001"),
  product_id = c("P001", "P002", "P001"),
  amount = c(10.0, 20.0, 15.0)
)

# 2. Parse and evaluate the first generated statement
revenue_by_customer_code <- generated_code["customer_id"]
cat("Executing code:\n", revenue_by_customer_code)
revenue_by_customer_dt <- eval(parse(text = revenue_by_customer_code))
print(revenue_by_customer_dt)

DBmaps documentation built on Sept. 9, 2025, 5:44 p.m.