core_object: Core Object API: Structured Output Generation

In aisdk: Unified Interface for AI Model Providers

Core Object API: Structured Output Generation

Description

Functions for generating structured objects from LLMs using schemas.

Generate a structured R object (list) from a language model based on a schema. The model is instructed to output valid JSON matching the schema, which is then parsed and returned as an R list.

Usage

generate_object(
  model = NULL,
  prompt,
  schema,
  schema_name = "result",
  system = NULL,
  temperature = 0.3,
  max_tokens = NULL,
  mode = c("json", "tool"),
  registry = NULL,
  ...
)

Arguments

model	Either a LanguageModelV1 object, or a string ID like "openai:gpt-4o".
prompt	A character string prompt describing what to generate.
schema	A schema object created by z_object(), z_array(), etc.
schema_name	Optional human-readable name for the schema (default: "result").
system	Optional system prompt.
temperature	Sampling temperature (0-2). Default 0.3 (lower for structured output).
max_tokens	Maximum tokens to generate.
mode	Output mode: "json" (prompt-based) or "tool" (function calling). Currently, only "json" mode is implemented.
registry	Optional ProviderRegistry to use (defaults to global registry).
...	Additional arguments passed to the model.

Value

A GenerateObjectResult with:

• object: The parsed R object (list)

• usage: Token usage information

• raw_text: The raw text output from the LLM

• finish_reason: The reason the generation stopped

Examples

if (interactive()) {
# Define a schema for the expected output
schema <- z_object(
  title = z_string(description = "Title of the article"),
  keywords = z_array(z_string()),
  sentiment = z_enum(c("positive", "negative", "neutral"))
)

# Generate structured object
result <- generate_object(
  model = "openai:gpt-4o",
  prompt = "Analyze this article: 'R programming is great for data science!'",
  schema = schema
)

print(result$object$title)
print(result$object$sentiment)
}

aisdk documentation built on May 29, 2026, 9:07 a.m.