📚 Supported Input Formats¶

This code generator supports the following input formats:

OpenAPI 3.0/3.1/3.2 (YAML/JSON, OpenAPI Data Types); OpenAPI 2.0 (Swagger) has limited support.
AsyncAPI 2.x/3.x (YAML/JSON).
JSON Schema (JSON Schema Core / JSON Schema Validation).
Apache Avro schema (.avsc, Apache Avro).
XML Schema (XSD).
Protocol Buffers / gRPC (.proto, Protocol Buffers / gRPC).
GraphQL schema (GraphQL Schemas and Types).
MCP tool schemas (--input-file-type mcp-tools, MCP Tool Schemas).
JSON / YAML / CSV data (converted to JSON Schema before model generation).
Python dictionary (converted to JSON Schema before model generation).
Existing Python types via --input-model: Pydantic models, dataclasses, Pydantic dataclasses, TypedDict, and dict schemas.

Use --input-file-type auto (the default) for common files, or set an explicit type when a file extension is ambiguous. For example, YAML can contain either an OpenAPI/JSON Schema document or raw sample data, so use jsonschema, openapi, or yaml depending on the intended input.

Input Format Guide¶

Input Format Guide (from code)¶

The tables below are generated from the input type enum, parser routing code, schema version enums, raw-data conversion rules, and parser type conversion maps.

Parser Routes and Version Flags¶

Input format	Selector	Parser route	`--schema-version`	Auto detection
JSON Schema	`jsonschema`	`JsonSchemaParser`	`draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	`$schema`, `type`, `properties`, or composition keywords
OpenAPI	`openapi`	`OpenAPIParser`	`3.0`, `3.1`, `3.2`, `auto`	`openapi` field
AsyncAPI	`asyncapi`	`AsyncAPIParser`	`2.0`, `3.0`, `auto`	`asyncapi` field
GraphQL schema	`graphql`	`GraphQLParser`	Not supported	Explicit only
XML Schema	`xmlschema`	`XMLSchemaParser`	`1.0`, `1.1`, `auto`	XML Schema namespace on the root element
Protocol Buffers	`protobuf`	`ProtobufParser`	`proto2`, `proto3`, `2023`, `auto`	Protocol Buffers syntax/message-like text
Apache Avro	`avro`	`AvroParser`	Not supported	Avro schema object, union, or primitive schema form
MCP tool schemas	`mcp-tools`	`JsonSchemaParser after MCP conversion`	Converted to JSON Schema; `draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	Explicit only
JSON data	`json`	`JsonSchemaParser after genson conversion`	Converted to JSON Schema; `draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	Mapping that is not a schema/OpenAPI/AsyncAPI/Avro document
YAML data	`yaml`	`JsonSchemaParser after genson conversion`	Converted to JSON Schema; `draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	Explicit for YAML sample data
CSV data	`csv`	`JsonSchemaParser after genson conversion`	Converted to JSON Schema; `draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	Detected from CSV-like text with consistent comma counts across non-empty lines or explicit `csv`
Python dictionary data	`dict`	`JsonSchemaParser after genson conversion`	Converted to JSON Schema; `draft-04`, `draft-06`, `draft-07`, `2019-09`, `2020-12`, `auto`	Explicit for mapping input
Python input model	`--input-model`	`JsonSchemaParser` after Python schema conversion	JSON Schema after conversion; dict input can select another explicit schema type	Explicit only

Accepted Source Shapes¶

Input format	Accepted source shape
JSON Schema	JSON Schema document as JSON/YAML, mapping, URL, or file
OpenAPI	OpenAPI document as JSON/YAML, mapping, URL, or file
AsyncAPI	AsyncAPI document as JSON/YAML, mapping, URL, or file
GraphQL schema	GraphQL SDL text, URL, or file
XML Schema	XSD XML text, URL, or file
Protocol Buffers	.proto text, file, directory, URL, or path list
Apache Avro	Avro schema JSON/YAML, mapping, list, URL, or file
MCP tool schemas	MCP tool list/profile as JSON/YAML, mapping, list, URL, or file
JSON data	JSON sample data text or file
YAML data	YAML sample data text or file
CSV data	CSV text or file with a header row and at least one data row
Python dictionary data	In-memory mapping or Python literal data
Python input model	`module:Object` or `path/to/file.py:Object` via `--input-model`

Format Type Coverage¶

Input family	Code-derived coverage	Guide
JSON Schema	7 schema types, 54 common formats	Uses JSON Schema type/format mappings and feature metadata below
OpenAPI	JSON Schema mappings plus 2 OpenAPI-only formats	Adds OpenAPI-specific schema features and formats
GraphQL	6 GraphQL type kinds	Uses GraphQL SDL parser order and parser method map
XML Schema	50 built-in XSD datatypes	Converts XSD built-ins to JSON Schema fragments
Protocol Buffers	15 scalar field types, 17 well-known type mappings	Converts descriptors to JSON Schema definitions
Apache Avro	8 primitives, 13 logical type mappings	Converts Avro schemas to JSON Schema while preserving Avro metadata
JSON/YAML/CSV/Dict data	4 raw data selectors	Samples are converted to JSON Schema with genson before parsing
Python input model	4 supported object kinds	Python objects are converted to schema data before normal generation

GraphQL Type Kinds¶

GraphQL kind	Parser method	Generated shape
`scalar`	`parse_scalar`	Generates scalar aliases
`enum`	`parse_enum`	Generates enums or literals depending on enum options
`interface`	`parse_interface`	Generates model classes from interface fields
`object`	`parse_object`	Generates model classes except root Query/Mutation objects
`input_object`	`parse_input_object`	Generates model classes for input objects
`union`	`parse_union`	Generates union type aliases

Apache Avro Primitive Types¶

Avro primitive	JSON Schema mapping	Constraints
`null`	`null`	-
`boolean`	`boolean`	-
`int`	`integer` + `int32`	-
`long`	`integer` + `int64`	-
`float`	`number` + `float`	-
`double`	`number` + `double`	-
`bytes`	`string` + `binary`	-
`string`	`string`	-

Apache Avro Logical Types¶

Avro logical type	Allowed Avro type	JSON Schema mapping
`decimal`	`bytes`, `fixed`	`string` + `decimal`
`big-decimal`	`bytes`	`string` + `decimal`
`uuid`	`string`, `fixed`	`string` + `uuid`
`date`	`int`	`string` + `date`
`time-millis`	`int`	`string` + `time`
`time-micros`	`long`	`string` + `time`
`timestamp-millis`	`long`	`string` + `date-time`
`timestamp-micros`	`long`	`string` + `date-time`
`timestamp-nanos`	`long`	`string` + `date-time`
`local-timestamp-millis`	`long`	`string` + `date-time-local`
`local-timestamp-micros`	`long`	`string` + `date-time-local`
`local-timestamp-nanos`	`long`	`string` + `date-time-local`
`duration`	`fixed`	`string` + `duration`

Protocol Buffers Scalar Types¶

Protobuf scalar	JSON Schema mapping	Constraints
`double`	`number` + `double`	-
`float`	`number` + `float`	-
`int64`	`integer` + `int64`	-
`uint64`	`integer` + `int64`	minimum=0, maximum=18446744073709551615
`int32`	`integer` + `int32`	-
`uint32`	`integer` + `int32`	minimum=0, maximum=4294967295
`sint32`	`integer` + `int32`	-
`sint64`	`integer` + `int64`	-
`fixed32`	`integer` + `int32`	minimum=0, maximum=4294967295
`fixed64`	`integer` + `int64`	minimum=0, maximum=18446744073709551615
`sfixed32`	`integer` + `int32`	-
`sfixed64`	`integer` + `int64`	-
`bool`	`boolean`	-
`string`	`string`	-
`bytes`	`string` + `binary`	-

Protocol Buffers Well-Known Types¶

Well-known type	JSON Schema mapping
`google.protobuf.Timestamp`	`string` + `date-time`
`google.protobuf.Duration`	`string` + `duration`
`google.protobuf.Struct`	`object` map
`google.protobuf.ListValue`	`array`
`google.protobuf.Value`	`null` \| `boolean` \| `number` \| `string` \| `object` map \| `array`
`google.protobuf.Any`	`object` map
`google.protobuf.Empty`	`object`
`google.protobuf.FieldMask`	`string`
`google.protobuf.DoubleValue`	`number` + `double` \| `null`
`google.protobuf.FloatValue`	`number` + `float` \| `null`
`google.protobuf.Int64Value`	`integer` + `int64` \| `null`
`google.protobuf.UInt64Value`	`integer` + `int64` \| `null`
`google.protobuf.Int32Value`	`integer` + `int32` \| `null`
`google.protobuf.UInt32Value`	`integer` + `int32` \| `null`
`google.protobuf.BoolValue`	`boolean` \| `null`
`google.protobuf.StringValue`	`string` \| `null`
`google.protobuf.BytesValue`	`string` + `binary` \| `null`

XML Schema Built-In Type Groups¶

JSON Schema mapping	XSD built-ins	Count
`Any`	`anySimpleType`, `anyAtomicType`, `anyType`	3
`string` + `uri`	`anyURI`	1
`string` + `byte`	`base64Binary`	1
`boolean`	`boolean`	1
`integer`	`byte`, `int`, `integer`, `long`, `negativeInteger`, `nonNegativeInteger`, `nonPositiveInteger`, `positiveInteger`, +5 more	13
`string` + `date`	`date`	1
`string` + `date-time`	`dateTime`, `dateTimeStamp`	2
`number` + `decimal`	`decimal`	1
`number`	`double`, `float`	2
`string`	`duration`, `ENTITY`, `gDay`, `gMonth`, `gMonthDay`, `gYear`, `gYearMonth`, `hexBinary`, +12 more	20
`string` + `duration`	`dayTimeDuration`	1
`array`	`ENTITIES`, `IDREFS`, `NMTOKENS`	3
`string` + `time`	`time`	1

Python Input Types¶

Python input object	Conversion behavior
`dict`	Returned directly as the schema; `--input-file-type` is required
`Pydantic v2 BaseModel`	Converted with Pydantic `model_json_schema()`
`dataclass`	Converted with Pydantic `TypeAdapter`; includes stdlib and Pydantic dataclasses
`TypedDict`	Converted with Pydantic `TypeAdapter`
Multiple `--input-model`	Supported only for Pydantic v2 BaseModel classes

📘 OpenAPI 3 and JSON Schema¶

Below are the data types and features recognized by datamodel-code-generator for OpenAPI 3 and JSON Schema.

Schema Feature Support (from code)¶

The JSON Schema and OpenAPI feature matrix below is generated from the same code metadata used by the schema version support page.

JSON Schema Features¶

Feature	Introduced	Status	Description
`Null in type array`	2020-12	✅ Supported	Allows `type: ['string', 'null']` syntax for nullable types
`$defs`	2019-09	✅ Supported	Uses `$defs` instead of `definitions` for schema definitions
`prefixItems`	2020-12	✅ Supported	Tuple validation using `prefixItems` keyword
`Boolean schemas`	Draft 6	✅ Supported	Allows `true` and `false` as valid schemas
`$id`	Draft 6	✅ Supported	Schema identifier field (`id` in Draft 4, `$id` in Draft 6+)
`definitions/$defs`	Draft 4	✅ Supported	Key for reusable schema definitions
`exclusiveMinimum/Maximum as number`	Draft 6	✅ Supported	Numeric `exclusiveMinimum`/`exclusiveMaximum` (boolean in Draft 4)
`readOnly/writeOnly`	Draft 7	✅ Supported	Field visibility hints for read-only and write-only properties
`const`	Draft 6	✅ Supported	Single constant value constraint
`propertyNames`	Draft 6	✅ Supported	Dict key type constraints via pattern, enum, or $ref
`contains`	Draft 6	⚠️ Partial	Count constraints are modeled when contains matches every item; general schema-valued contains is not supported
`deprecated`	2019-09	⚠️ Partial	Marks schema elements as deprecated
`if/then/else`	Draft 7	❌ Not Supported	Conditional schema validation
`contentMediaType/contentEncoding`	Draft 7	⚠️ Partial	Content type and encoding hints for strings
`contentSchema`	2019-09	⚠️ Partial	Schema for decoded string content
`$anchor`	2019-09	✅ Supported	Location-independent schema references
`$vocabulary`	2019-09	❌ Not Supported	Vocabulary declarations for meta-schemas
`unevaluatedProperties`	2019-09	⚠️ Partial	Additional properties not evaluated by subschemas
`unevaluatedItems`	2019-09	⚠️ Partial	Additional items not evaluated by subschemas
`dependentRequired`	2019-09	❌ Not Supported	Conditional property requirements
`dependentSchemas`	2019-09	❌ Not Supported	Conditional schema application based on property presence
`$recursiveRef/$recursiveAnchor`	2019-09	✅ Supported	Recursive reference resolution via anchors
`$dynamicRef/$dynamicAnchor`	2020-12	✅ Supported	Dynamic reference resolution across schemas

OpenAPI-Specific Features¶

Feature	Introduced	Status	Description
`nullable`	OAS 3.0	✅ Supported	Uses `nullable: true` for nullable types (deprecated in 3.1)
`discriminator`	OAS 3.0	✅ Supported	Polymorphism support via `discriminator` keyword
`webhooks`	OAS 3.1	✅ Supported	Top-level webhooks object for incoming events
`$ref with sibling keywords`	OAS 3.1	⚠️ Partial	$ref can coexist with description, summary (no allOf workaround)
`itemSchema`	OAS 3.2	✅ Supported	Media Type Object item schema for sequential media
`$self`	OAS 3.2	✅ Supported	Root document URI for relative and absolute reference resolution
`querystring`	OAS 3.2	✅ Supported	Query string parameter object without a parameter name
`xml`	OAS 3.0	⚠️ Partial	XML serialization metadata (name, namespace, prefix)
`externalDocs`	OAS 3.0	⚠️ Partial	Reference to external documentation
`links`	OAS 3.0	❌ Not Supported	Links between operations
`callbacks`	OAS 3.0	❌ Not Supported	Callback definitions for webhooks
`securitySchemes`	OAS 3.0	❌ Not Supported	API security mechanism definitions

✅ Implemented data types and features¶

Implemented Data Types and Formats¶

The schema type, format, and default Pydantic v2 type columns below are generated from the parser's schema format registry and the default Pydantic v2 type mapping; keyword and note columns document supplemental schema details.

Schema Data Types¶

Schema Type	Default Pydantic v2 Type	Supported Keywords
`integer`	`int`	maximum, exclusiveMaximum, minimum, exclusiveMinimum, multipleOf
`number`	`float`	maximum, exclusiveMaximum, minimum, exclusiveMinimum, multipleOf
`string`	`str`	pattern, minLength, maxLength
`boolean`	`bool`	-
`object`	`Dict[str, Any]`	properties, required, additionalProperties, patternProperties
`null`	`None`	-
`array`	`List[Any]`	items, prefixItems, minItems, maxItems, uniqueItems

Common Formats (JSON Schema + OpenAPI)¶

Schema Type	Format	Default Pydantic v2 Type	Notes
`integer`	`default` (no `format`)	`int`	-
`integer`	`int32`	`int`	-
`integer`	`int64`	`int`	-
`integer`	`date-time`	`AwareDatetime`	-
`integer`	`unix-time`	`int`	-
`integer`	`unixtime`	`int`	-
`number`	`default` (no `format`)	`float`	-
`number`	`float`	`float`	-
`number`	`double`	`float`	-
`number`	`decimal`	`Decimal`	-
`number`	`date-time`	`AwareDatetime`	-
`number`	`time`	`time`	-
`number`	`time-delta`	`timedelta`	-
`number`	`unixtime`	`int`	-
`string`	`default` (no `format`)	`str`	-
`string`	`byte`	`Base64Str`	Base64 encoded string
`string`	`date`	`date`	-
`string`	`date-time`	`AwareDatetime`	-
`string`	`timestamp with time zone`	`AwareDatetime`	-
`string`	`date-time-local`	`NaiveDatetime`	-
`string`	`duration`	`timedelta`	-
`string`	`time`	`time`	-
`string`	`time-local`	`time`	-
`string`	`path`	`Path`	-
`string`	`email`	`EmailStr`	Requires email-validator
`string`	`idn-email`	`EmailStr`	Requires email-validator
`string`	`idn-hostname`	`str`	-
`string`	`iri`	`str`	-
`string`	`iri-reference`	`str`	-
`string`	`uuid`	`UUID`	-
`string`	`uuid1`	`UUID1`	-
`string`	`uuid2`	`UUID`	-
`string`	`uuid3`	`UUID3`	-
`string`	`uuid4`	`UUID4`	-
`string`	`uuid5`	`UUID5`	-
`string`	`uri`	`AnyUrl`	-
`string`	`uri-reference`	`str`	-
`string`	`uri-template`	`str`	-
`string`	`json-pointer`	`str`	-
`string`	`relative-json-pointer`	`str`	-
`string`	`regex`	`str`	-
`string`	`hostname`	`str`	-
`string`	`ipv4`	`IPv4Address`	-
`string`	`ipv4-network`	`IPv4Network`	-
`string`	`ipv6`	`IPv6Address`	-
`string`	`ipv6-network`	`IPv6Network`	-
`string`	`decimal`	`Decimal`	-
`string`	`integer`	`int`	-
`string`	`unixtime`	`int`	-
`string`	`ulid`	`ULID`	Requires python-ulid
`boolean`	`default` (no `format`)	`bool`	-
`object`	`default` (no `format`)	`Dict[str, Any]`	-
`null`	`default` (no `format`)	`None`	-
`array`	`default` (no `format`)	`List[Any]`	-

OpenAPI-Only Formats¶

Schema Type	Format	Default Pydantic v2 Type	Notes
`string`	`binary`	`bytes`	File content
`string`	`password`	`SecretStr`	-

🔗 Other schema¶

enum (as enum.Enum or typing.Literal)
allOf (as Multiple inheritance)
anyOf (as typing.Union)
oneOf (as typing.Union)
$ref (http extra is required when resolving $ref for remote files.)
$id (for JSONSchema)