Support expr values in value_mappings by amc-corey-cox · Pull Request #195 · linkml/linkml-map

amc-corey-cox · 2026-04-08T14:40:10Z

Summary

Extend value_mappings so each KeyVal entry can use an expr field (evaluated against source bindings) instead of a literal value. Specifying both is an error.
Add _resolve_key_val method and lazy bindings init in the populated_from + value_mappings path
Add _expand_keyval_dicts preprocessing to handle ReferenceValidator normalization when KeyVal has more than two fields
Deprecate expression_to_value_mappings and expression_to_expression_mappings in the schema ahead of 1.0 removal

Closes #165

Test plan

Scaffold test: expr-valued mapping with uuid5() and source field bindings
Scaffold test: literal value mapping (backward compat)
Error test: both value and expr set raises
Edge case: no-match returns None
Full suite: 584 passed, 4 skipped

🤖 Generated with Claude Code

Extend value_mappings so each entry can use an expr field (evaluated against source bindings) instead of a literal value. Deprecate expression_to_value_mappings and expression_to_expression_mappings ahead of 1.0 removal. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Pull request overview

Extends the transformer spec and runtime to allow value_mappings entries to compute their mapped values via an expr (evaluated with source bindings), while preserving backward-compatible literal mappings and deprecating older expression-mapping fields.

Changes:

Add KeyVal.expr support and resolve mapped values via a new _resolve_key_val helper in the populated_from + value_mappings path.
Pre-expand shorthand dict[str, KeyVal] values (e.g., "A": Admin) prior to ReferenceValidator normalization to avoid normalization failures after KeyVal gains extra fields.
Add tests covering expr-valued mappings, literal backward compatibility, mutual-exclusion error, and no-match behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/test_transformer/test_object_transformer_new.py	Adds integration/unit tests for expr-valued and literal `value_mappings`, plus error/no-match cases.
src/linkml_map/transformer/transformer.py	Adds preprocessing to expand shorthand KeyVal dict values before normalization.
src/linkml_map/transformer/object_transformer.py	Resolves `value_mappings` outputs via literal `value` or evaluated `expr`, with lazy bindings init.
src/linkml_map/datamodel/transformer_model.yaml	Adds `KeyVal.expr` and deprecates older expression-mapping fields in the schema.
src/linkml_map/datamodel/transformer_model.py	Updates generated Pydantic models/metadata to reflect `KeyVal.expr` and deprecations.

Unify expression evaluation: extract _eval_expr from _derive_from_expr so _resolve_key_val shares the same eval path (including unrestricted_eval fallback). Fix KeyVal bindings type signature to Bindings | None. Fix double-space typo in deprecation message. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

…g-expr # Conflicts: # src/linkml_map/datamodel/transformer_model.py # src/linkml_map/transformer/object_transformer.py

After the _derive_slot extraction, bindings is always initialized unconditionally in map_object, so the | None is no longer needed. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Instead of adding expr to KeyVal (which polluted the shared slot namespace and required a ReferenceValidator shim), add a dedicated expression_mappings field on ElementDerivation. KeyVal stays clean (key + value only), the _expand_keyval_dicts shim is removed, and the runtime handles expression_mappings as a fallback after value_mappings in _derive_slot. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

YAML silently coerces unquoted true/false to booleans and bare numbers to integers, causing silent lookup misses against the stringified source value. Note this in value_mappings and expression_mappings descriptions. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

amc-corey-cox · 2026-04-10T21:33:25Z

Hold on deprecating expression_to_value_mappings

While reviewing issue #99 (scalar binning for enums), we found a compelling use case for expression_to_value_mappings on enum derivations.

The pattern: when a slot derivation routes a numeric (or string) value to a target enum via range: TargetEnum, the enum derivation needs a way to classify that value into a PV. expression_to_value_mappings fits naturally here — the keys are boolean expressions using value(), and the values are target PV names:

enum_derivations:
  BPCategoryEnum:
    expression_to_value_mappings:
      "value() <= 89": LOW
      "value() >= 90 and value() <= 119": NORMAL
      "value() >= 120 and value() <= 139": HIGH
      "value() >= 140": VERY_HIGH

This avoids the semantic overloading problem we'd have if we reused expression_mappings (which means something different on slot derivations).

expression_to_expression_mappings still has no compelling use case — we can proceed with deprecating that one. But expression_to_value_mappings should stay.

expression_to_value_mappings has a compelling use case on enum derivations for scalar binning (issue #99). Remove the deprecation and update the description to reflect the intended usage: boolean expression keys evaluated with value() for classifying incoming values into permissible values. expression_to_expression_mappings remains deprecated.

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Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

When both tables contain the same key, value_mappings (literal) should win. Locks in the documented fallthrough behavior.

Copilot AI review requested due to automatic review settings April 8, 2026 14:40

amc-corey-cox mentioned this pull request Apr 8, 2026

Implement expression_to_expression_mappings in transformer runtime #127

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Comment thread src/linkml_map/transformer/object_transformer.py Outdated

Merge branch 'main' of github.com:linkml/linkml-map into value-mappin…

a9ba6ad

…g-expr # Conflicts: # src/linkml_map/datamodel/transformer_model.py # src/linkml_map/transformer/object_transformer.py

amc-corey-cox force-pushed the value-mapping-expr branch from 2182627 to a9ba6ad Compare April 8, 2026 19:33

Tighten _resolve_key_val signature: bindings is never None

5a45802

After the _derive_slot extraction, bindings is always initialized unconditionally in map_object, so the | None is no longer needed. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot AI review requested due to automatic review settings April 8, 2026 19:45

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Comment thread src/linkml_map/transformer/transformer.py Outdated

amc-corey-cox and others added 2 commits April 8, 2026 16:57

Extract _apply_mappings from _derive_slot

697cf7e

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot AI review requested due to automatic review settings April 8, 2026 21:59

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Comment thread src/linkml_map/datamodel/transformer_model.yaml

Comment thread src/linkml_map/datamodel/transformer_model.yaml

amc-corey-cox requested review from madanucd and turbomam April 10, 2026 12:34

amc-corey-cox mentioned this pull request Apr 10, 2026

Standardize how to map scalar binning Enums to a corresponding scalar slot #99

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Comment thread src/linkml_map/datamodel/transformer_model.yaml

Comment thread src/linkml_map/transformer/object_transformer.py

Add test for value_mappings precedence over expression_mappings

008be0a

When both tables contain the same key, value_mappings (literal) should win. Locks in the documented fallthrough behavior.

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Support expr values in value_mappings#195

Support expr values in value_mappings#195
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value-mapping-expr

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amc-corey-cox commented Apr 8, 2026

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amc-corey-cox commented Apr 10, 2026

Hold on deprecating expression_to_value_mappings

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