Export lineage as a Mermaid flowchart

Serializes a lineage object to Mermaid flowchart text. Mermaid renders natively in GitHub markdown, Quarto, and most documentation tools, so this is the exporter to reach for when lineage should live in the docs: paste the output into a ```mermaid code fence and the diagram renders with no R, no htmlwidget, and no JavaScript bundle.

Usage

lineage_mermaid(lineage, path = NULL)

Arguments

lineage

The result of extract_lineage(), or any list with nodes and edges built with create_table_node() and create_column_edge().

path

Optional file to write the Mermaid text to. When supplied, the string is returned invisibly.

Value

A string containing the Mermaid flowchart definition.

Details

Each table becomes a subgraph containing its columns, colored by table type with the same palette as lineage_flow(). Non-identity edges are labeled with the column's defining expression, and indirect edges (from extract_lineage(include_indirect = TRUE)) draw dashed.

See also

extract_lineage() to compute lineage automatically

Other lineage exporters: lineage_graphml(), lineage_json(), lineage_openlineage()

Examples

lineage <- list(
  nodes = list(
    create_table_node("orders", c("order_id", "amount")),
    create_table_node("daily_totals", "total", table_type = "target")
  ),
  edges = list(
    create_column_edge("orders", "amount", "daily_totals", "total")
  )
)
cat(lineage_mermaid(lineage))
#> flowchart LR
#>   subgraph orders["orders"]
#>     orders_order_id["order_id"]
#>     orders_amount["amount"]
#>   end
#>   subgraph daily_totals["daily_totals"]
#>     daily_totals_total["total"]
#>   end
#>   orders_amount --> daily_totals_total
#>   classDef source fill:#f0f7ff,stroke:#3b82f6,color:#1d4ed8
#>   classDef transform fill:#fef3f2,stroke:#f59e0b,color:#d97706
#>   classDef target fill:#f0fdf4,stroke:#10b981,color:#059669
#>   class orders source
#>   class daily_totals target

# Ready to paste into a GitHub README or Quarto document:
cat("```mermaid\n", lineage_mermaid(lineage), "```\n", sep = "")
#> ```mermaid
#> flowchart LR
#>   subgraph orders["orders"]
#>     orders_order_id["order_id"]
#>     orders_amount["amount"]
#>   end
#>   subgraph daily_totals["daily_totals"]
#>     daily_totals_total["total"]
#>   end
#>   orders_amount --> daily_totals_total
#>   classDef source fill:#f0f7ff,stroke:#3b82f6,color:#1d4ed8
#>   classDef transform fill:#fef3f2,stroke:#f59e0b,color:#d97706
#>   classDef target fill:#f0fdf4,stroke:#10b981,color:#059669
#>   class orders source
#>   class daily_totals target
#> ```