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[FEATURE](pyspark) PySpark validation generated from the Pydantic schema#518

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[FEATURE](pyspark) PySpark validation generated from the Pydantic schema#518
Seth Fitzsimmons (sethfitz) wants to merge 9 commits into
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pyspark-codegen

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@sethfitz Seth Fitzsimmons (sethfitz) commented May 11, 2026

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Summary

Adds a new runtime package (overture-schema-pyspark) plus a new output target in overture-schema-codegen that emits PySpark validation expressions and conformance tests from the same Pydantic models that define the schema. Ships an overture-validate CLI (to be merged with the overture-schema CLI later; that will be an opportunity to improve its ergonomics) for running the validation against Parquet on disk or in S3.

PySpark plugs in as a peer of the existing Markdown output target: same ModelSpec extraction, same four-layer architecture (Discovery -> Extraction -> Output Layout -> Rendering), new pipeline module. The codegen abstraction is model-general (ModelSpec = RecordSpec | UnionSpec: one record that compiles to a Spark StructType, or a tagged union of records); in this schema every model is an Overture feature, so the generated modules are organized by theme/feature. See packages/overture-schema-codegen/docs/design.md for the full picture; the "PySpark Pipeline" section there covers the new stages in detail.

What's in the PR

packages/overture-schema-pyspark/ -- runtime. Public API in validate.py (validate_model, explain_errors), schema comparison in schema_check.py, dataclasses in check.py, the overture-validate CLI in cli.py, and shared expression building blocks in expressions/{constraint_expressions,column_patterns,_schema_structs}.py. The per-feature expression modules under expressions/generated/overture/schema/<theme>/<feature>.py and per-feature conformance tests under tests/generated/overture/schema/<theme>/test_<feature>.py are emitted by codegen and confined to a generated/ boundary that make generate-pyspark wipes and recreates. _registry.py walks that tree at import time and exposes REGISTRY: dict[str, ModelValidation] keyed by each module's ENTRY_POINT value (e.g. "overture.schema.transportation:Segment"), reading each module's emitted MODEL_VALIDATION constant, plus a parallel PARTITION_MAP derived from each module's PARTITIONS dict for partitioned features.

Validation degrades gracefully when columns are skipped (--skip-columns / --suppress) or structurally absent from the data. Every check declares the top-level columns it reads, and a check over a missing column -- top-level, nested inside an array or map (sources[].confidence resolves to sources), or model-level -- is dropped before Spark planning rather than raising a raw AnalysisException. ValidationResult.absent_columns surfaces the columns dropped for this reason, and the CLI backstop classifies any residual planning error through the structured PySpark error API so a generator bug propagates as a traceback instead of being mistaken for a missing column.

This has been tested to work with Spark versions 3.4.0 - 4.1.1 (and the lowest-direct CI check will verify that it continues to work with the lowest declared PySpark version, which is currently 3.4).

Adam Lastowka (@Rachmanin0xFF) the public API changed since the previous version you tested (the entry point is now validate_model, returning a ValidationResult, in an attempt to simplify how it gets integrated with the CDP). If you point me to its current state, I can propose an update that uses the new API.

packages/overture-schema-codegen/src/overture/schema/codegen/pyspark/ -- new output target. Pipeline stages:

ModelSpec (from extraction)
    |
constraint_dispatch.py    constraints -> ExpressionDescriptor / ModelConstraintDescriptor
    |
check_builder.py          FieldShape tree -> Check / ModelCheck IR
                          (check_ir.py; resolves array nesting, map key/value
                          projection, variant gating via
                          FieldPath = ScalarPath | ArrayPath | MapPath and Guard
                          sum types)
schema_builder.py         FieldShape tree -> SchemaField list (StructType source)
test_data/                ModelSpec -> BASE_ROW_SPARSE / BASE_ROW_POPULATED, scaffold,
                          invalid_value
    |
renderer.py               Check IR -> per-feature expression module
test_renderer.py          Check IR -> per-feature conformance test module
    |
pipeline.py               orchestrates, returns GeneratedModule list

make generate-pyspark wipes both generated/ trees and recreates them; make check gates on regeneration being current.

What's covered

Every constraint Pydantic enforces today is dispatched to a PySpark expression, which allows Spark to push down predicates and take advantage of Catalyst to avoid unnecessary deserialization:

  • Field constraints: Ge / Gt / Le / Lt / Interval, ArrayMinLen / ArrayMaxLen / ScalarMinLen / ScalarMaxLen (typed length constraints split by attachment layer), StrippedConstraint, PatternConstraint, UniqueItemsConstraint, GeometryTypeConstraint, JsonPointerConstraint.
  • Map key/value constraints: dict-typed fields (e.g. names.common, a dict[LanguageTag, StrippedString] present on most named features) have their per-key and per-value constraints validated by projecting map_keys / map_values and applying the same field checks. A map value that is a sub-model is descended into, validating its field and model-level constraints. dict[K, Any] maps (e.g. Infrastructure.source_tags) carry no constraint and emit no checks; container-valued map values (a list or map inside a map value) are not yet supported and raise at generation time rather than emit an unanchored check.
  • NewType overrides: LinearlyReferencedRange (length / bounds / order).
  • Base-type overrides: HttpUrl (format + length), EmailStr, BBox (completeness, lat ordering, lat range).
  • Model constraints: RequireAnyOfConstraint, RadioGroupConstraint, RequireIfConstraint, ForbidIfConstraint, MinFieldsSetConstraint. MinFieldsSetConstraint mirrors Pydantic's model_fields_set semantics: required fields are always set (the constructor enforces them) and count toward the threshold alongside any explicitly-set optional fields. NoExtraFieldsConstraint is intentionally skipped, as its behavior is implicit when using DataFrames.

Known semantic gaps / differences

Divergences from Pydantic:

  • UniqueItemsConstraint uses Spark's array_distinct, which compares whole elements with structural equality on raw stored values. Pydantic compares normalized Python objects -- e.g., list[HttpUrl] is compared after URL normalization (such as ensuring that URLs like http://example.com contain a trailing /: http://example.com/). The PySpark check catches exact duplicates, not duplicates after normalization.
  • require_any_of checks isNotNull as a proxy for Pydantic's model_fields_set. Parquet has no equivalent of "explicitly provided" because of the tabular nature of DataFrames; isNotNull is stricter (it rejects fields explicitly set to null).
  • BBox's PySpark expressions include checking latitude ordering and range. Longitude is skipped due to undefined behavior around how we handle features that cross the antimeridian.
  • Regex checks run on the JVM, so a PatternConstraint is evaluated with Java's regex dialect rather than Python's -- the two agree for the schema's patterns, but ASCII-vs-Unicode shorthand classes (\w, \d) and interior-newline handling differ in general.

CLI

$ overture-validate --help
Usage: overture-validate [OPTIONS] FEATURE_TYPE PATH

  Validate Overture data at PATH and write annotated Parquet.

Options:
  -o, --output TEXT            Output path for validated Parquet.
  --head INTEGER               Error rows to display.  [default: 20]
  --conf TEXT                  Spark config key=value pairs.
  --count-only                 Report error count only; skip explain/unpivot.
  --skip-schema-check          Warn on schema mismatches instead of aborting.
  --skip-columns TEXT          Columns declared absent from data; skips their
                               checks.
  --ignore-extra-columns TEXT  Extra data columns to ignore in schema
                               comparison.
  --suppress TEXT              Suppress checks: FIELD (all checks) or
                               FIELD:CHECK (specific).
  --help                       Show this message and exit.

Output is one row per violation: feature ID, theme/type, failing field, check name, message, offending value.

Testing

overture-schema-codegen generates conformance tests alongside the PySpark expressions as a sanity-check by evaluating expected-good and expected-bad rows within a single DataFrame (setup/teardown overhead for DataFrame-per-test-case was much too high). Each feature gets two baseline rows -- BASE_ROW_SPARSE (required fields only) and BASE_ROW_POPULATED (every optional field filled in) -- and every scenario is exercised against both, so checks that depend on optional structure being present are covered as well as the minimal-row case.

make check generates tests and runs the full suite over everything, which use PySpark and increase test runtime (again; they run in just over a minute for me). testmon was introduced to improve the developer experience by skipping tests that weren't affected by recent edits.

Beyond the unit and conformance tests:

# Local Parquet
overture-validate segment samples/segment.parquet --count-only

# Real release prefix (expect bbox Float-vs-Double mismatch -> use --skip-schema-check)
# partitions (theme=places, type=place) will automatically be detected
# note that the s3a protocol must be used when AWS-provided Hadoop filesystem JARs are not available
overture-validate place s3a://overturemaps-us-west-2/release/<release>/ --skip-schema-check --head 50

Notes for review

  • This PR is intentionally large because the generated tree is large. The interesting surface is smaller: pyspark/{constraint_dispatch,check_builder,check_ir,schema_builder,renderer,test_renderer,pipeline}.py plus the path IR in overture-schema-system's field_path.py and the runtime in overture-schema-pyspark/src/overture/schema/pyspark/. Everything under generated/ is regenerable output -- review the codegen, but skim the output to understand the shape of what's produced.
  • Bundles supporting changes (testmon for incremental test runs, VehicleSelectorBase extraction, Java 17 CI pin, build/CI hardening so test-all runs unconditionally and the check job triggers on the Makefile/workflow themselves, typing-extensions declared) rather than splitting them into separate PRs.
  • The branch has been squashed to a single commit; expect a force-push. The review/refactoring/hardening pass is complete.

Closes #517.

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github-actions Bot commented May 11, 2026

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🗺️ Schema reference docs preview is live!

🌍 Preview https://staging.overturemaps.org/schema/pr/518/schema/index.html
🕐 Updated Jun 24, 2026 03:51 UTC
📝 Commit 1c21815
🔧 env SCHEMA_PREVIEW true

Note

♻️ This preview updates automatically with each push to this PR.

pytest-testmon tracks which tests cover which source files and skips
unaffected tests on subsequent runs. Activated via a TESTMON Makefile
variable so the default `make check` uses incremental selection while
`make check TESTMON=` runs the full suite.

Lock the dependency in the dev group, gitignore the local cache file,
and thread $(TESTMON) through the test, test-all, and test-only
targets.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
Pull the shared `dimension` and `comparison` fields of the five vehicle
selector subtypes into a `VehicleSelectorBase` parent, and thread
`discriminator="dimension"` through the `VehicleSelector` annotated
union.

The discriminator turns the union into a Pydantic discriminated union,
so it serializes as JSON Schema's `oneOf` + `discriminator` rather than
`anyOf`. Regenerated segment_baseline_schema.json captures the new
shape.

This is a prerequisite for downstream tooling that walks discriminated
unions structurally (e.g. PySpark codegen for segment's nested vehicle
scoping).

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
Replace the Tonga-based Division/DivisionArea/DivisionBoundary
fixtures with Kauaʻi County samples that exercise admin_level,
capital_division_ids, wikidata, and source license alongside the
existing fields.

Replace the Tonga-based Connector/Segment fixtures with a Vermooten
Street junction in Pretoria that exercises access_restrictions with
when.vehicle, speed_limits with when.heading, routes with ref,
road_surface, and multi-source attribution.

Reformat the TOML with 4-space indents and sorted keys to match
sibling theme packages.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
Introduce overture-schema-pyspark, a runtime PySpark validation
package whose per-feature expression modules and conformance tests
are generated from the same Pydantic models that define the schema,
along with an `overture-validate` CLI.

Runtime (overture-schema-pyspark/src/overture/schema/pyspark/):

- check.py — Check, CheckShape, FeatureValidation dataclasses.
- schema_check.py — write-first comparison of Spark schemas against
  an expected StructType, with structural type matching and
  SchemaMismatch reporting.
- validate.py — public API: validate_feature(), evaluate_checks(),
  explain_errors(). The explain stage UNPIVOTs per-row check results
  into one row per violation, preserving all input columns for
  downstream join-back.
- cli.py — `overture-validate <parquet-or-directory>` runs the
  validation pipeline against a path of GeoParquet files. Output is
  one row per violation: feature ID, theme/type, failing field,
  check name, offending value. Single-pass evaluation keeps memory
  bounded for arbitrarily large inputs.
- expressions/ — shared runtime utilities (constraint_expressions,
  column_patterns, _schema_structs). Per-feature expression modules
  live under expressions/overture/ and are added by the codegen in
  a follow-up commit.
- tests/_support/ — conformance test infrastructure (scenarios,
  harness, helpers, mutations). The harness builds one DataFrame
  per feature, applies all scenarios as deterministic-UUID-tagged
  rows, runs validation once, and indexes violations back to
  scenario IDs — O(checks) rather than O(checks * scenarios).

CLI filtering options:

  --theme <theme>           limit to one theme
  --feature <feature>       limit to one feature type
  --skip-schema-check       run only constraint checks (no schema
                            comparison)
  --count-only              print violation counts per check rather
                            than rows
  --suppress <key>          suppress specific (feature, field, check)
                            triples per a YAML config

Codegen pipeline (overture-schema-codegen/src/.../pyspark/):

    FeatureSpec
        |
    constraint_dispatch.py   map constraints to descriptors
        |
    check_builder.py         walk FieldSpec -> CheckNode IR;
                             resolve array nesting, variant gating
        |
    schema_builder.py        FieldSpec -> SchemaField list
                             (StructType source)
        |
    renderer.py              CheckNode -> per-feature expression
                             module
    test_renderer.py         CheckNode -> per-feature conformance
                             test module
    synthetic.py             FeatureSpec -> BASE_ROW + invalid values
        |
    pipeline.py              orchestrate, return GeneratedModule list

The dispatch tables map every supported constraint (Ge/Gt/Le/Lt/
Interval, MinLen/MaxLen, StrippedConstraint, PatternConstraint,
UniqueItemsConstraint, GeometryTypeConstraint, JsonPointerConstraint,
RequireAnyOfConstraint, RadioGroupConstraint, RequireIfConstraint,
ForbidIfConstraint, MinFieldsSetConstraint), NewType (Country-
CodeAlpha2, LinearlyReferencedRange, RegionCode), and base type
(HttpUrl, EmailStr) to constraint_expressions check functions.

Discriminated unions (segment is the canonical hard case) split
into per-arm test files. The codegen handles arm splitting via
generate_arm_rows in synthetic.py and _filter_field_nodes_for_arm
in test_renderer.py.

The Makefile gains a `generate-pyspark` target and gates `check`
on it so a stale generation surfaces immediately. The CLI is exposed
as a `[project.scripts]` entry point so `overture-validate`
becomes available after `pip install` / `uv sync`.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
Generate PySpark expressions (and tests) for models defined in the
workspace

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
PySpark 3.4 (the declared floor) doesn't run on Java 21, the default
JDK on ubuntu-latest runners -- it hits NoSuchMethodException on
java.nio.DirectByteBuffer.<init>(long, int), removed in JDK 21. Pin
the lowest-direct cell to Java 17 so the resolved pyspark==3.4.0 can
actually start. The default cell (which resolves to a current pyspark
4.x) keeps the runner's default Java 21.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
validate_feature built check expressions referencing every column the
schema declares, then evaluated them with an eager df.select. When the
input DataFrame lacked a declared column, Spark's plan analysis raised
an AnalysisException before the caller could inspect the schema
mismatch, so a file missing a required column produced a Java stack
trace instead of the schema-mismatch report the CLI is built to emit.

Columns that compare_schemas reports as absent from the data now have
their checks dropped, the same as --skip-columns columns; referencing
them is what crashes Spark. The mismatch is still recorded in
schema_mismatches, so the CLI reports it and exits cleanly (or, with
--skip-schema-check, validates the columns that are present).

The CLI also prints the --skip-columns invocation for the absent
columns, so the escape hatch is discoverable from the error itself.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
Model-level constraints (require_any_of and the like) generated for a
sub-model reached through an optional field fired even when that field
was null. Pydantic skips a model validator when the optional sub-model
is absent, so the generated PySpark expression produced a false positive
the schema itself never raises.

ModelCheck now carries a gate: the optional-ancestor path that must be
non-null for the constraint to apply. check_builder sets it when the
constrained model is reached via an optional struct field inside an
array; the renderer wraps the constraint in
F.when(<accessor>.isNotNull(), ...).

Regenerated Segment expressions: the speed_limits[].when,
access_restrictions[].when, and prohibited_transitions[].when
require_any_of checks are now skipped when their when sub-model is null.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
@vcschapp

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This PR is intentionally large because the generated tree is large. The interesting surface is smaller: pyspark/{constraint_dispatch,check_builder,check_ir,schema_builder,renderer,test_renderer,pipeline}.py plus the runtime in overture-schema-pyspark/src/overture/schema/pyspark/. Everything under generated/ is regenerable output -- review the codegen, but skim the output to understand the shape of what's produced.

This seems reasonable for as a basis for review, but for merging, I don't see the upside in committing 15-30 generated files and 15K-30K generated lines to source control—we want to source control the generator, not the generatee, right?

@vcschapp

Victor Schappert (vcschapp) commented May 27, 2026

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Divergence from Python no. 1 comment.

  • UniqueItemsConstraint uses Spark's array_distinct, which compares whole elements with structural equality on raw stored values. Pydantic compares normalized Python objects -- e.g., list[HttpUrl] is compared after URL normalization (such as ensuring that URLs like http://example.com contain a trailing /: http://example.com/). The PySpark check catches exact duplicates, not duplicates after normalization.

Basically we're saying PySpark will slightly under-count duplicates in some rare edge cases. While annoying, this doesn't seem like it's a very big deal.

@vcschapp

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Divergence from Pydantic no. 3 question:

  • BBox's PySpark expressions include checking latitude ordering and range. Longitude is skipped due to undefined behavior around how we handle features that cross the antimeridian.

Does this mean we have stricter constraints in the PySpark than in Pydantic? If yes, shouldn't they be the same?

@vcschapp

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Regarding @no_extra_fields:

NoExtraFieldsConstraint is intentionally skipped, as its behavior is implicit when using DataFrames.

This is true in terms of struct-typed columns, but isn't it not true for a top-level dataframe? i.e. Doesn't it mean that if I have a model like:

@no_extra_fields
class Foo(BaseModel):
    bar: int

And a dataframe like:

bar baz qux
42 "garply" 3.14

Wouldn't the baz and qux columns sneak through without causing a violation?

@vcschapp

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Divergence from Pydantic no. 2 comment:

  • require_any_of checks isNotNull as a proxy for Pydantic's model_fields_set. Parquet has no equivalent of "explicitly provided" because of the tabular nature of DataFrames; isNotNull is stricter (it rejects fields explicitly set to null).

Let's see if I understand this right.

I have a model like this:

@require_any_of("bar", "baz")
class Foo(BaseModel):
    bar: int | None = None
    baz: str | None = None

I think you're saying that Pydantic would allow Foo(bar=None) because bar is set explicitly but PySpark would reject it...

The latest version of the Pydantic should also reject it... The docs say:

To ensure parity between Python and JSON Schema validation, a field's value must be explicitly set to a non-None value to satisfy the constraint. Fields whose value was set by Pydantic using a default value violate the constraint, as do fields explicitly set to None.

That seems to be the current behavior:

>>> from pydantic import BaseModel
>>> from overture.schema.system.model_constraint import require_any_of
>>> @require_any_of("bar", "baz")
... class Foo(BaseModel):
...     bar: int | None = None
...     baz: str | None = None
... 
>>> Foo(bar=None)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/ANT.AMAZON.COM/schapper/overture/schema/.venv/lib/python3.10/site-packages/pydantic/main.py", line 250, in __init__
    validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self)
pydantic_core._pydantic_core.ValidationError: 1 validation error for Foo
  Value error, at least one of these fields must be set to a value other than None, but none are: bar, baz (`@require_any_of`) [type=value_error, input_value={'bar': None}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/value_error

Am I missing something, or did you actually achieve perfect parity?

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Nice work on this.

It's a huge PR, but I think the successfulness of it is best captured by this comment:

Every constraint Pydantic enforces today is dispatched to a PySpark expression, which allows Spark to push down predicates and take advantage of Catalyst to avoid unnecessary deserialization ...

That's phenomenal.

A few points to discuss, with my biggest items being committing of generated code; and some minor conceptual issues around the use of the word "feature".

Comment on lines +10 to +11
These are codegen-internal classes -- Pydantic users continue to write
`Annotated[X, MinLen(n)]` in their schemas; the wrapping happens inside

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For my understanding: Does Field(max_length=n) also produce this type of internal constraint, or is that a different code path?

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Good catch; that should say Field(max_lenth=n).

{% from '_check_function.py.jinja2' import check_function -%}
# This file is auto-generated by overture-schema-codegen. Do not edit.

"""{{ feature_title }} validation expression builders."""

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Naming question regarding "feature": can this handle any BaseModel that gets pulled in via discovery, or does it have to be a "feature"—and if so, what flavor of feature?

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It can handle any BaseModel.

Comment on lines +244 to +249
FeatureSpec: TypeAlias = ModelSpec | UnionSpec
"""Top-level feature types passed through the extraction pipeline.

Consumers narrow with `isinstance` when an arm-specific attribute
is needed (e.g. `UnionSpec.discriminator_field`).
"""

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I didn't realize this before, but this seems to be overloading the term "feature" to mean basically, "a thing that is either derived from BaseModel, or a union of such things"; whereas in system and common we use "feature" to mean a geospatial feature, i.e., a thing with geometry and related attributes.

Can we use some more neutral naming for this type and the things flowing from it?

  • RootSpec
  • TopLevelSpec
  • TargetSpec

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True. That was probably in the back of my head because I was thinking about validating Overture Features as its primary purpose even while the implementation was more generic.

None of those names really resonate, but I'll see if I can come up with something that feels less overloaded. Something that properly encompasses ModelSpec | UnionSpec (where UnionSpec is implicitly "union of models"). If we weren't dealing with unions, ModelSpec could be appropriate. PrimarySpec (complementing SupplementarySpec, which encompasses enums, NewTypes, nested models, other types) feels close.

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I went with renaming FeatureSpec to ModelSpec (in line with Pydantic conventions) and ModelSpec turned into RecordSpec to distinguish it from UnionSpec.

@sethfitz

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This seems reasonable for as a basis for review, but for merging, I don't see the upside in committing 15-30 generated files and 15K-30K generated lines to source control—we want to source control the generator, not the generatee, right?

We agreed in one of the Schema WG meetings to drop the generated code from the PR to merge (once we've reviewed it), as it can be regenerated on demand and will exist in published packages for posterity.

Basically we're saying PySpark will slightly under-count duplicates in some rare edge cases. While annoying, this doesn't seem like it's a very big deal.

Exactly. Agreed.

Does this mean we have stricter constraints in the PySpark than in Pydantic? If yes, shouldn't they be the same?

For BBox, yes. We're going to follow up with Adam Lastowka (@Rachmanin0xFF) and the Data Platform folks to understand what their validation requirements + desires are today (in PySpark) and eventually make sure that PySpark and Pydantic are equivalent.

Wouldn't the baz and qux columns sneak through without causing a violation?

No, these would be rejected when checking the Spark schema (before moving into per-row validation).

require_any_of checks isNotNull as a proxy for Pydantic's model_fields_set. Parquet has no equivalent of "explicitly provided" because of the tabular nature of DataFrames; isNotNull is stricter (it rejects fields explicitly set to null).
Am I missing something, or did you actually achieve perfect parity?

I did achieve parity with Pydantic, but wanted to call this out because of the ability to omit values there (and when using JSON).

This lands map key/value validation in the PySpark and Markdown
generators, renames the codegen's core "feature" vocabulary to "model",
and closes correctness gaps across validation generation, constraint
identity, base-row synthesis, and the runtime checks.

Map key/value validation (PySpark). Dict-typed fields such as
names.common (dict[LanguageTag, StrippedString], present on nearly every
feature with names) got no key or value validation, so invalid
language-tag keys and unstripped values passed overture-validate while
failing Pydantic. A MapPath IR locates a map's keys or values, the check
builder descends into MapOf.key/.value, and the renderer emits
map_keys_check/map_values_check over F.map_keys/F.map_values, reusing
the null-guarded array transform. A map value that is a sub-model is
descended into the way a list element is, so its field and model-level
constraints generate checks. Shapes with no representable MapPath -- a
container nested in a map value, an array-shaped map projection, a map
reached through an array -- raise at generation time rather than
silently drop a constraint or emit a mis-typed check.

Map key/value rendering (Markdown). Map references render every key and
value type and their directly-applied constraints. Map sides link to
their type pages, container wrappers (a list or map inside a map)
survive instead of being peeled, model-valued map values link, and every
variant is named rather than collapsing to map<K, ?>. A bare side folds
into the surrounding map<...> code span so two adjacent backtick spans
cannot corrupt the CommonMark.

feature to model vocabulary. The codegen generates validation for any
Pydantic BaseModel, not only geospatial features, so the root
abstraction is now ModelSpec (a RecordSpec, or a tagged UnionSpec of
records) and the runtime surface is validate_model, model_keys,
model_names, ModelValidation, and the emitted MODEL_VALIDATION constant,
in place of validate_feature, feature_keys, feature_names,
FeatureValidation, and FEATURE_VALIDATION. The registry walks the new
constant name and the module template is renamed to match. The
overture-validate CLI argument and the GeoJSON-feature validator keep
feature vocabulary, where the geospatial meaning is correct.

Graceful degradation over absent and skipped columns. Each Check carries
one read_columns set, the top-level columns it actually reads, replacing
the split root_field/referenced_fields mechanism that left an
unresolvable F.col() for a row-root constraint over a struct field and
for an in-array constraint branching on a row-root discriminator. Checks
whose columns are skipped or structurally absent -- top-level, nested
(sources[].confidence resolves to sources), or model-level -- are
dropped before Spark instead of crashing with a raw AnalysisException.
The CLI backstop classifies the exception through the structured PySpark
error API rather than its message text, so a real planning bug
propagates as a traceback instead of steering the operator to suppress
it with --skip-columns. ValidationResult exposes absent_columns, the
same derivation that drives check dropping. evaluate_checks and
explain_errors reject input columns colliding with their reserved
_err_N, field, check, and message names.

Field-check label disambiguation. Discriminated unions produced multiple
field checks sharing a (field, name) identity -- segment emitted two
required checks on access_restrictions[].when.vehicle[].value, and
sources[].confidence collided on bounds across many models -- leaving
colliding rows indistinguishable in suppression, explain_errors
metadata, and the conformance expected_field. Symmetric _N suffixes
disambiguate them, computed over the unfiltered check list so per-arm
test filtering cannot hide a collision the shared expression module
still carries. Label and disambiguated function-name derivation is
unified into one flattening shared by the expression and test renderers,
which also fixes a per-arm asymmetry where a model-check base label
spanning an arm boundary made the per-arm test expect a field the module
never emits.

Base-row and test-data value synthesis. Row synthesis handles
Not(FieldEqCondition), used by Division and DivisionBoundary as
~IS_COUNTRY, instead of silently treating it as unsatisfied, and merges
every bound constraint on a field before choosing a value so
both-exclusive intervals and sibling Gt/Lt constraints are jointly
satisfied. forbid_if fill values are typed for non-string scalars (0,
0.0, False) rather than falling back to a string sentinel for a
non-string column. One CONSTRAINT_VALUES table pairs the valid and
invalid value for each string constraint, replacing two parallel tables
that drifted silently. SparkCategory dispatch is exhaustive: an
unhandled or binary category raises at generation time instead of
emitting a wrong fill value. Raw Field(pattern=) handling fails loud on
an uncurated pattern naming the table to update, and requires
PydanticMetadata before reading an object's .pattern, restoring the
unhandled-constraint TypeError contract.

Constraint identity. Deduplication compares constraints by value. System
FieldConstraint subclasses inherited object identity, so two
structurally identical UniqueItemsConstraint or PatternConstraint
instances reported as divergent for any union field shared across
members. FieldConstraint now defines value equality and hashing keyed on
the concrete type and normalized instance state, reducing a compiled
re.Pattern to (pattern, flags) so a case-insensitive pattern is not
masked and reducing container attributes to hashable forms, so a set of
constraints deduplicates by rule. The union fingerprint compares the
constraint objects directly, falling back to a value-stable repr only
for pydantic's internal Field() metadata, the lone constraint type that
still compares by identity. Constraint attributes must themselves be
value types, a contract the base states for future authors.

Runtime checks. check_geometry_type reads the full four-byte WKB type
word and normalizes ISO and EWKB encodings to the OGC base type, so 3D
(Z/M/ZM) geometries in GeoParquet no longer false-fail every
geometry-type check. check_url_format matches the scheme
case-insensitively, matching Pydantic's HttpUrl. check_bounds rejects
NaN under a lower-only bound, which Spark's ordering otherwise lets
pass. resolve_read completes a partial partition path, appending a
type=Y leaf below a theme=X/ path so one feature's checks no longer run
against every type sharing a theme directory. A compiled, flagged
re.Pattern, the only Pydantic carrier for re.IGNORECASE, is honored in
both the pyspark check and the markdown display instead of crashing the
model's generation.

Variant gating and extraction. A discriminated union reached under a
struct prefix, and a gate crossing mismatched array nesting, raise
rather than emit a mis-gated check; both are preemptive, since no
current schema reaches that state. Forward-ref and self-referential
field annotations resolve against their owning model before
classification rather than crashing the terminal classifier on an
unresolved string. A required list[X | None] field no longer inherits
is_optional from element nullability.

Build, structure, and docs. The check-python-code CI paths trigger on
the Makefile and the workflow themselves, uv-sync no longer routes its
errors to /dev/null, and test-all runs the full suite unconditionally so
golden-JSON and example-only changes are not deselected by testmon.
typing-extensions is declared to match its unconditional import. Shared
helpers replace duplicated logic -- register_model, schema_const_name,
enum_source, a struct-only-prefix predicate, and a model-spec discovery
entry point that gives every discovery site one extraction carrying
partition layout -- and several docstrings and CLI help strings are
corrected to match current behavior.

Signed-off-by: Seth Fitzsimmons <seth@mojodna.net>
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Validate Overture data on Spark against the Pydantic schema

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