create_schema: Create a structured output schema

In rollama: Communicate with 'Ollama' to Run Large Language Models Locally

Create a structured output schema

Description

Build a JSON Schema for structured output. Pass named type objects as arguments, or supply raw JSON via .schema. These functions specify a JSON schema that LLMs can be told to use in their outputs. This is particularly effective for structured data extraction. Their names are based on the JSON schema, which is what the APIs expect behind the scenes. See the structured outputs article for a tutorial.

• type_boolean(), type_integer(), type_number(), and type_string() each represent scalars. These are equivalent to length-1 logical, integer, double, and character vectors (respectively).

• type_enum() is equivalent to a length-1 factor; it is a string that can only take the specified values.

• type_array() is equivalent to a vector in R. You can use it to represent an atomic vector: e.g. type_array(type_boolean()) is equivalent to a logical vector and type_array(type_string()) is equivalent to a character vector). You can also use it to represent a list of more complicated types where every element is the same type (R has no base equivalent to this), e.g. type_array(type_array(type_string())) represents a list of character vectors.

• type_object() is equivalent to a named list in R, but where every element must have the specified type. For example, type_object(a = type_string(), b = type_array(type_integer())) is equivalent to a list with an element called a that is a string and an element called b that is an integer vector.

• type_ignore() is used in tool calling to indicate that an argument should not be provided by the LLM. This is useful when the R function has a default value for the argument and you don't want the LLM to supply it.

• type_from_schema() allows you to specify the full schema that you want to get back from the LLM as a JSON schema. This is useful if you have a pre-defined schema that you want to use directly without manually creating the type using the ⁠type_*()⁠ functions. You can point to a file with the path argument or provide a JSON string with text. The schema must be a valid JSON schema object.

Usage

create_schema(
  ...,
  .description = NULL,
  .additional_properties = FALSE,
  .schema = NULL
)

type_string(description = NULL, required = TRUE)

type_boolean(description = NULL, required = TRUE)

type_integer(description = NULL, required = TRUE)

type_number(description = NULL, required = TRUE)

type_enum(values, description = NULL, required = TRUE)

type_array(items, description = NULL, required = TRUE)

type_object(
  .description = NULL,
  ...,
  .required = TRUE,
  .additional_properties = FALSE
)

Arguments

...	Named rollama type objects representing top-level properties.
.description, description	Optional description for the schema.
.additional_properties	Whether to allow additional properties.
.schema	A raw JSON string or file path to use as the schema directly.
values	A character vector of allowed values.
items	A rollama type object describing the array items.
.required, required	Whether this field is required in the parent object.

See Also

query() and chat() where the schema is passed via the format argument. Structured outputs article for a tutorial.

rollama documentation built on Aug. 24, 2026, 9:08 a.m.