llm_render_messages: Render tidy messages without calling any API

In LLMR: Interface for Large Language Model APIs in R

Render tidy messages without calling any API

Description

Returns the per-row message objects that llm_fn() / llm_mutate() would build from prompt or .messages, using the same internal renderer they use. No request is sent and no file is read or encoded; a "file" role stays a (glued) path string. Use this to inspect templating, roles, and multimodal wiring before spending anything.

Usage

llm_render_messages(
  .data,
  prompt = NULL,
  .messages = NULL,
  .system_prompt = NULL,
  rows = NULL
)

Arguments

.data	A data.frame/tibble whose columns feed the glue templates.
prompt	A single glue template string (mutually exclusive with .messages).
.messages	A character vector of glue templates, optionally named by role ("system", "user", "assistant", "file"). Unnamed entries default to "user".
.system_prompt	Optional system string, prepended when a row has no "system" message.
rows	Optional integer vector selecting which rows to render (default: all rows).

Value

A list of length length(rows) (default nrow(.data)). Each element is either a bare character scalar (prompt only, no system) or a role-named character vector, identical to what the call path would dispatch.

See Also

llm_preview() for a row-level summary with issue flags and the batch plan; llm_fn(), llm_mutate().

Examples

df <- data.frame(text = c("good", "bad"), stringsAsFactors = FALSE)
llm_render_messages(df, prompt = "Sentiment of: {text}")
llm_render_messages(
  df,
  .messages = c(system = "Be terse.", user = "Rate: {text}")
)

LLMR documentation built on July 11, 2026, 1:06 a.m.