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lancedb/docs/web/integrations/data/pydantic.mdx
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Jack Ye ddb318567a docs: complete SQL reference, enrich Functions drafts, rename OSS to Embedded (#4732)
## Summary

- Complete the SQL reference: `ATTACH DATABASE`, the `CHANGES` clause,
and
`dedupe()`/`duplicate_pairs()` (verified against current sophon source;
these were recently renamed from
`vector_dedup`/`vector_duplicate_pairs`).
  Fix the blob-column default-projection claim and add the previously
  undocumented `blob_descriptor()`.
- Enrich the gated Functions draft (still `.mintignore`'d, pre-release):
  chained Functions over blob outputs, GPU-produced blobs, Secrets,
  multi-input/output binding, `code=[module]` packaging.
- Upgrade the materialized-view and computed-column auto-refresh drafts
with
  precise, verified catch-up semantics, and add the missing `ALTER
  MATERIALIZED VIEW` / `CREATE ... WITH(...)` sections (also gated — the
  automatic-refresh scheduler is still dev/staging-only).
- Thread one running example (video frames → GPU extract/caption → dedup
→
auto-refreshing materialized view) through Functions, materialized
views,
and the LeRobotDataset integration guide instead of a separate tutorial.
- Rename "LanceDB OSS"/"OSS" to "LanceDB Embedded"/"Embedded" throughout
  (52 files); activate the existing availability-comparison mechanism on
  `basics/offerings.mdx` for a full feature-by-feature comparison table.
2026-10-29 10:16:03 -07:00

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---
title: "Pydantic"
sidebarTitle: "Pydantic"
availability:
embedded: available
enterprise: available
---
import {
PyFrameworksPydanticBaseExample,
PyFrameworksPydanticBaseModel,
PyFrameworksPydanticImports,
PyFrameworksPydanticSetUrl,
PyFrameworksPydanticTypeConversion,
PyFrameworksPydanticVectorField,
} from '/snippets/integrations.mdx';
[Pydantic](https://docs.pydantic.dev/latest/) is a data validation library in Python.
LanceDB integrates with Pydantic for schema inference, data ingestion, and query result casting.
Using `lancedb.pydantic.LanceModel`, users can seamlessly
integrate Pydantic with the rest of the LanceDB APIs.
First, import the necessary LanceDB and Pydantic modules:
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticImports}
</CodeBlock>
Next, define your Pydantic model by inheriting from `LanceModel` and specifying your fields including a vector field:
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticBaseModel}
</CodeBlock>
Set the database connection URL:
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticSetUrl}
</CodeBlock>
Now you can create a table, add data, and perform vector search operations:
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticBaseExample}
</CodeBlock>
## Vector Field {#vector-field}
LanceDB provides a `lancedb.pydantic.Vector` method to define a
vector Field in a Pydantic Model.
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticVectorField}
</CodeBlock>
This example demonstrates how LanceDB automatically converts Pydantic field types to their corresponding Apache Arrow data types. The `pydantic_to_schema()` function takes a Pydantic model and generates an Arrow schema where:
- `int` fields become `pa.int64()` (64-bit integers)
- `str` fields become `pa.utf8()` (UTF-8 encoded strings)
- `Vector(768)` becomes `pa.list_(pa.float32(), 768)` (fixed-size list of 768 float32 values)
- The `False` parameter indicates that the fields are not nullable
## Type Conversion {#type-conversion}
LanceDB automatically convert Pydantic fields to
[Apache Arrow DataType](https://arrow.apache.org/docs/python/generated/pyarrow.DataType.html#pyarrow.DataType).
Current supported type conversions:
| Pydantic Field Type | PyArrow Data Type |
| ------------------- | ----------------- |
| `int` | `pyarrow.int64` |
| `float` | `pyarrow.float64` |
| `bool` | `pyarrow.bool` |
| `str` | `pyarrow.utf8()` |
| `list` | `pyarrow.List` |
| `BaseModel` | `pyarrow.Struct` |
| `Vector(n)` | `pyarrow.FixedSizeList(float32, n)` |
LanceDB supports to create Apache Arrow Schema from a
`pydantic.BaseModel`
via `lancedb.pydantic.pydantic_to_schema` method.
<CodeBlock filename="Python" language="Python" icon="python">
{PyFrameworksPydanticTypeConversion}
</CodeBlock>
This example shows a more complex Pydantic model with various field types and demonstrates how LanceDB handles:
- Basic types: `int` and `str` fields
- Vector fields: `Vector(1536)` creates a fixed-size list of 1536 float32 values
- List fields: `List[int]` becomes a variable-length list of int64 values
- Schema generation: The `pydantic_to_schema()` function automatically converts all these types to their Arrow equivalents