History
Changelog
Pre-1.0, a minor release may break compatibility. When it does, the break is spelled out here with a migration note — that is the deal in exchange for the version number.
All notable changes to this project are documented here. The format follows Keep a Changelog, and the project follows Semantic Versioning — with the pre-1.0 caveat that a minor release may break compatibility, in which case the break is spelled out below.
0.6.0 — 2026-09-13#
A naming release. No change to the grammar or to the semantics of evaluation:
open-predicate-schema.json is byte-identical to 0.5.0 apart from three lines — its $id, its
title and its $comment — and the $id still names v0.4.0, because the $id version tracks
the grammar and the grammar did not move. Consumers pinning that $id have only the new namespace
to re-point at.
Changed#
The name is settled, and the project has a dedicated organisation. OpenPredicate is stewarded by the OpenPredicate organisation, whose purpose is to carry the grammar to an open standard and push for its adoption. This is the single pass the README promised: the repository, both package names, the schema
$id, the problem-type URIs, the CLI and the vendor keyword all derive from the one namespace, so nothing is left half-named.Name Repository OpenPredicate/open-predicateSchema file open-predicate-schema.jsonSchema $idhttps://openpredicate.tech/schema/v0.4.0/open-predicate-schema.jsonProblem types https://openpredicate.tech/problems/…npm package open-predicateGitHub Packages @openpredicate/open-predicateCLI open-predicate-generateVendor keyword x-open-predicateGenerator config open-predicate.config.jsonMigration. Mechanical, and only for identifiers — no filter valid before this release becomes invalid, because the grammar and the evaluation semantics did not move. In a resource schema, the vendor keyword the generator reads is
x-open-predicate; any other spelling is silently ignored, so a field you meant to exclude would become queryable. Point any$refor pinned$idat the$idabove, and any RFC 9457typematching at the problem base above. A generator config file isopen-predicate.config.json, or pass it explicitly with--config. The$idstill namesv0.4.0— the version tracks the grammar, which is unchanged; only the namespace it sits under is new. Nothing was ever served or published under any other namespace or package name, so no working deployment can be pinned elsewhere.On the entries below. Past releases are written up in these names, so the whole document reads in one vocabulary. Released artefacts are unaffected — this names the project, not history.
Added#
- Brand assets, in
assets/. The{ > }mark — JSON braces around a comparison — as SVG and as raster at three sizes, plus a wordmark for light and dark backgrounds.assets/README.mdstates the palette and the usage rules. The README now opens with the mark. MIT-licensed with the rest of the repository.
0.5.0 — 2026-09-13#
A tooling release. No change to the grammar or to the semantics of evaluation:
open-predicate-schema.json is byte-identical to 0.4.0 apart from its root description, and its
$id still names v0.4.0, because the $id version tracks the grammar and the grammar did not
move. Consumers pinning that $id have nothing to do.
What did move is the generator, which is now the thing an API provider uses when implementing
search: point it at the resource schema, state the slice of the language you can actually serve,
and get back a filter schema that permits exactly that slice plus a capability document that
describes it honestly. It also travels with the package for the first time, as a bin named
open-predicate-generate, rather than being a file inside a repository nobody installs.
SPEC.md gains two clarifications in service of that, both about what an implementation may claim rather than about what a filter means: §2.1 says out loud that accepting part of a profile is permitted and advertising it is not, and §2.2 documents the capability document's top-level members. No filter valid under 0.4.0 becomes invalid.
Added#
- The generator selects capabilities, not just profiles
(#11). Profiles are the unit
a server advertises, but three shapes do not fit inside one: a backend with
LIKEand noPOSITIONsupports$likeand not$contains; a key-value store cannot implement$existsat all; a provider compiling to a flat conjunctive index wants one AND level and no shorthand. Six new knobs, each available as a flag and as a JS API option —--operators,--drop-operators,--no-shorthand,--max-filter-depth,--limits, and--configto hold the combination. What is declined is absent from the generated schema, so a client learns it from validation rather than from anunsupported-operatorat runtime. Defaults are unchanged: with none of them given the output is byte-identical to before. --config <file>, andexamples/pet.open-predicate.config.json. The capability selection is a decision about the endpoint, not a shell invocation, so it goes in a JSON file checked in beside the resource schema and regenerated from. Its keys are the JS API's option names plusresource,outandcapabilities; relative paths in it resolve against its own directory, an explicit flag beats it, and an unrecognised key is refused rather than ignored — a misspelled key is a capability that silently did not apply.npm run generate:examplenow runs through one.--max-filter-depth <n>caps how deep$and/$or/$nor/$notmay nest:1is a flat filter offering no logical operators at all,2permits one level of them. JSON Schema cannot count how deep an instance already is, so the filter is emitted as a chain of levels: level i offers the logical operators over level i+1 and the last level does not offer them at all. Every level shares the operand$defs, so the cost is n copies of a map of$refs. Field-level$notis bounded to a single application by the same flag — under Kleene logic¬¬X ≡ Xeven for UNKNOWN, so a negated negation says nothing the plain constraint does not.--limits <json|@file>puts the SPEC §7 numbers a provider actually enforces into the capability document. They were emitted unconditionally, so every document generated from the CLI claimedmaxDepth: 10, maxClauses: 100, maxSetLength: 1000whether or not that was true. Where--max-filter-depthis given andmaxDepthis not, the enforced bound is published.- The generator is part of the package.
tools/was not inpackage.jsonfilesand there was nobinentry, so the tool the README points readers at could not travel with the package at all. It is now abinnamedopen-predicate-generate, withopen-predicate/generateexportinggenerateFilterSchemafor programmatic use. This repository still publishes no artifacts (RELEASING.md), so the command is reachable from a clone or a git install and not from npmjs; what changed is that it is ready to be, andnpm packnow contains it. - SPEC.md §2.2 documents the capability document's
top-level members —
queryLanguage,profiles,fields,limitsandfilterSchema— in a table beside the existing per-field one.limitsappeared in the example and in no table, andfilterSchema,itemValuesandnullablewere emitted by the generator and described nowhere. No normative change to what the members mean. - SPEC.md §2.1 says what a partial profile may and may not do. The
rule was already there — a profile other than
coreis implemented in full or not at all — but it read as a prohibition on the implementation rather than on the advertisement. An endpoint accepting part of a profile is not prohibited from existing; it states what it accepts per path and omits the incomplete profile fromprofiles. examples/mcp-server/— a runnable MCP server whose one tool,search_pets, takes a filter as itsfilterargument and nothing else. The tool'sinputSchemaisexamples/pet.filter.jsoninlined verbatim; validation is ajv against that same file, and execution is the SQL compiler fromexperiments/filter-to-sqlover an in-memory SQLite table, so the queries are real.node examples/mcp-server/demo.mjsdrives it over stdio and prints a transcript: two filters that answer, one that shows the$unknownAsdifference (4 matches against 7), and the three valid-but-wrong filters from README §Exposing search to an agent being rejected with a pointer at the clause.npm run example:mcpandnpm run example:mcp:demoare the entry points.- The example is also the first place the
$id-when-inlining hazard is written down: nested underproperties.filter, a bundled schema's self-references resolve against its own$id, so removing the$idbreaks it — ajv fails to compile it at all.
Changed#
- The capability document's
profilesreports coverage rather than the request. It echoed whatever--profileswas given; it now lists only the profiles the final operator set covers in full, because SPEC.md §2.1 makes a partial profile one an implementation may not advertise.--drop-operators '$contains'therefore costs thestringsclaim, and the per-fieldoperatorslists carry what is on offer instead — with a warning on stderr naming the operator responsible. Declining acoreoperator dropscoretoo, and warns that the result is not a conforming implementation. Nothing changes for a selection that is whole profiles, which is every invocation before this release. - Positioned as one JSON-Schema-described query language with two integration points, rather
than as an agent interface. An earlier revision in this same unreleased window led with the MCP
tool definition and moved §Exposing search to an agent ahead of the OpenAPI and generator
sections; that ordering is reverted and the "search interface for agents" framing is gone from
the README, the
package.jsondescription and the repository description. The agent use case keeps its section and its runnable server — it is one of the two things the schema is for, not the thing the document opens with. - The schema's root
descriptionlikewise leads with the shared-grammar framing again, and mentions inlining as a tool's input schema second. Non-normative prose; no validator behaviour changes. - The error format is no longer mandated. SPEC.md §8 required
RFC 9457 Problem Details with media type
application/problem+json. It now requires only that a rejected filter be answered with400 Bad Requestand that the response say which of the five conditions applies —malformed-query,unknown-field,unsupported-operator,invalid-operand,query-too-complex— because that is what a client branches on. The envelope is the API's own: an API with an established error format should express these conditions in it rather than carry a second format for one endpoint. RFC 9457 remains the RECOMMENDED default where there is none, and thetypeURIs, thepointermember and the recovery members (queryableFields,accepted) are unchanged as its encoding. This relaxes a requirement, so nothing that conformed before stops conforming.
Fixed#
--max-depthaccepted a value that was not a number. It was coerced withNumber()and never checked, so--max-depth deepbecameNaNand silently stopped the walk at the first nested object. It and--max-filter-depthare both validated now.- An operator whose dependency was dropped is dropped with it.
$flagscarriesdependentRequired: ["$regex"]out of the grammar, so--drop-operators '$regex'would have left$flagsinpropertieswith a rule naming a memberadditionalProperties: falseforbids — present in the schema and impossible to use. The closure is read off$defs/ConstraintObject, so a dependency added later is handled by construction. - Generated filter schemas were not a narrowing (#8).
tools/generate-filter-schema.mjscarried the published constraint object'sdependentRequiredrule but not itsdependentSchemasone, so{"microchip": {"$unknownAs": false}}— a modifier with nothing to modify — passed a generated schema whileopen-predicate-schema.jsonrejected it. A server following the documented path (generated schema as the tool'sinputSchema, published semantics behind it) then had to evaluate a filter with no predicate in it; the SQL compiler inexperiments/filter-to-sqlemittedcoalesce((), FALSE)and the database answered with a syntax error. The generator now reads both dependency keywords off$defs/ConstraintObjectinstead of restating either, so a rule added there reaches generated schemas with the version that introduces it, andexamples/pet.filter.jsonis regenerated: 12 of its 18 constraint objects gain the rule — the ones offering$unknownAs, which is every field that can be absent or null. The$commentjustifying the rule is deliberately not copied along with it: a validator never reads it, and one copy per field is charged by the token to whoever inlines the schema in a tool definition. No change to the grammar — this is the generator agreeing with it. - The narrowing property is now tested as a property.
tests/generator.test.mjsasserted it over a hand-written list of fifteen filters, which can only re-check the leaks someone already thought of — the keyword above was dropped for as long as the list existed. It now samples filters out of each generated schema's own vocabulary (tests/fuzz.mjs, seeded, deterministic) and asserts that every one the generated schema accepts is valid OpenPredicate, over three generated schemas; the run is checked for not being vacuous, in that it must accept a fraction of its samples and must reach every operator the schema offers. A second test pins what the generator does with each instance-constraining keyword of$defs/ConstraintObject, so adding one there fails the suite until it is handled. experiments/filter-to-sqlrejects a constraint object with no predicate in it rather than emitting an empty expression —malformed-query, at the pointer of the offending clause. Both schemas already reject these, so this only matters for a compiler reached another way, but the failure it replaces was a500from the database.- The prose in README §Errors, COMPARISON.md §4, the
OpenAPI examples and
experiments/filter-to-sqlfollows: they now describe Problem Details as the recommended shape rather than the required one, and name the failing condition where they previously said "problem". The examples still model RFC 9457, since it is still the default a greenfield API should pick.
0.4.0 — 2026-09-07#
Breaking. The $id is now …/v0.4.0/open-predicate-schema.json. This release resolves the
three operator overlaps that an external review and this repository's own
experiments/filter-to-sql flagged independently; the design and the evidence are in
decisions/0001-array-quantifiers-and-unknown-handling.md.
The headline is that the language had two unrelated mechanisms for looking inside an array —
$elemMatch and the [*] path segment — and one mechanism now does both jobs while naming its
quantifier. Operator count is unchanged at 34.
Added#
$someand$every(profilecollections), the element quantifiers. Each takes aFilterwhen the elements are objects — paths inside resolve against the element — or a constraint object when they are scalars.$someis$elemMatchrenamed;$everyis new, because universal quantification over elements was not previously expressible:$notover$someis "no element matches", which is a different predicate.$unknownAs(profilecore), a boolean modifier on a constraint object that resolves that constraint's UNKNOWN.{"status": {"$ne": "archived", "$unknownAs": true}}is the one-clause form of the$or/$isNulllonghand this specification prescribed before. It applies last — after every sibling operator, including a field-level$not— and SPEC.md §4.6 gives the scope rules and the nine-case proof that resolution distributes over three-valued AND. It requires at least one operator beside it.- A truth-table column for
$norin §4.1, and a note that all three connectives are commutative so the six rows cover all nine combinations.$nor's three-valued result previously had to be derived, and the derivation was the trap. $everyon generated schemas, and$unknownAson exactly the fields where UNKNOWN is reachable — the same rule the generator already applied to$existsand$isNull. On a property that is required all the way up and cannot hold null, the modifier would be a constant, so it is omitted and the trap disappears from the tool definition entirely.
Removed — breaking#
$elemMatch. Renamed to$some. Mechanical:{"items": {"$elemMatch": {…}}}→{"items": {"$some": {…}}}.$hasAnyand$hasNone. Both were compositions of a quantifier and$in, and their presence beside whole-value$inwas the whole$in-versus-membership confusion.{"tags": {"$hasAny": ["a"]}}→{"tags": {"$some": {"$in": ["a"]}}};{"tags": {"$hasNone": ["a"]}}→{"tags": {"$not": {"$some": {"$in": ["a"]}}}}.- The
[*]wildcard path segment, from the §3.2 grammar. It expressed nothing the equivalent$someclauses do not: per-constraint existential scope is exactly what an$andof separate$someclauses means.{"items[*].qty": {"$gt": 2}}→{"items": {"$some": {"qty": {"$gt": 2}}}}. Three further reasons it went: living in the path grammar made it the only construct present in every profile includingcore, so no server could decline it; it contradicted §4.2 by revoking$exists's totality; and it cost 1.74× the SQL of the equivalent$elemMatchplus a table-valued join per clause. The schema now rejects a[*]path outright, including in$fieldposition, so a stale filter is a validation error rather than a path read as a literal key name. $defs/ScalarSet.$inand$ninnow take$defs/OperandSet, the same set definition the collection operators use. The two definitions had silently diverged —$hasAnyaccepted$fieldreferences and object members while$inaccepted only scalars — with nothing in the specification acknowledging it. The unification is toward the permissive side, so no filter that was valid becomes invalid.
Changed — breaking#
- A type-mismatched equality is FALSE, not UNKNOWN. §4.3 said comparing different JSON types
yields UNKNOWN; §5.1 defined
$eqas structural equality, under which a string and a number are simply unequal. The two readings are indistinguishable under$eqand differ under$ne, and the specification asserted both. It is now settled as FALSE for the equality family ($eq,$ne,$in,$nin,$hasAll) and UNKNOWN for ordering, string and array operators, with a table in §4.3. This changes result sets without changing any filter's shape, so a mechanical rewrite will not surface it:{"notes": {"$ne": 3}}now matches a record whosenotesis"hello". - An empty array under a former wildcard clause.
[*]on[]was UNKNOWN, because the path resolved to nothing;$someon[]is FALSE, because an empty array is a resolved value and nothing in it satisfies the condition.$everyon[]is TRUE, vacuously. Observable under negation only, and it is the one migration step a codemod cannot claim to preserve. - §3.4 resolution is single-valued. With no wildcard segment, a path yields zero values or exactly one. The sequence model is gone.
- Six operator descriptions that contradicted §4.1. These strings are vendored verbatim into
generated schemas and MCP tool definitions, so they were a first-order cause of the confusion
rather than a cosmetic issue.
$nor's was outright wrong — "None of the listed filters may evaluate TRUE" is the two-valued reading — and$ne's said only "Field does not equal the operand".$nin,$nbetween,$nlikeand$nilikeall read as total predicates. Every negative operator now states what it does with UNKNOWN. - §1 no longer calls the filter "a boolean function" while §4.1 makes it three-valued.
$existsis documented as unconditionally total. It always was, except under a wildcard path; with those gone the exception is gone.- §3.5 settles whether an index suffix is a separate path. It is not:
items[0]is the fielditemsfor queryability, while a named member beneath it (items[0].sku) is its own path. - §7 addresses quantifier cost.
$someand$everyare the expensive operators on most backends, and a server that cannot afford them can decline thecollectionsprofile — which is precisely what the[*]segment made impossible.
Fixed#
$some/$every's operand shape is no longer ambiguous.anyOf: [Filter, ConstraintObject]overlaps on a leading$not, and nothing said which was meant. §5.8 now gives a decidable rule: scan for the first member that can only be one of the two, recursing through$not/$and/$or/$norbodies when the outer member is itself ambiguous.$fieldinside a quantifier resolves against the element, stated in §5.8 and §5.11. §5.11 said "the same record" while §5.8 said paths were element-relative; both readings were defensible.
0.3.1 — 2026-09-04#
No change to the schema, the grammar or the semantics. open-predicate-schema.json is
byte-identical to 0.3.0 and its $id still names v0.3.0, because the $id version tracks the
grammar and the grammar did not move. Consumers pinning that $id have nothing to do.
Removed#
- Publishing. The release workflow no longer ships to npmjs.com or GitHub Packages. Neither
registry ever received a copy, and neither should before the name is final: publishing claims a
name, and npm blocks a name from reuse permanently once it has been published and unpublished.
.github/workflows/release.ymlnow only verifies a release — the test suite, and the tag-against-package.jsoncheck — and uploads nothing. TheNPM_TOKENsecret and.github/scripts/version-published.share deleted with it. RELEASING.md keeps what the jobs needed, so they can be restored from git history rather than rewritten.
Changed#
- README no longer offers an install that does not exist. The Quickstart opened with
npm install --save-dev open-predicate, which the README's own Status table already contradicted two screens further down. It now vendors the file bycurl, which is the only way to obtain the schema and always was. - RELEASING.md documents the process that exists — a tag and a GitHub Release, carrying notes and a source snapshot and nothing else.
0.3.0 — 2026-09-04#
Guidance for adopters exposing a search endpoint to an LLM agent, the tooling that acts on it,
and an honest statement of how finished this is. No grammar change: every filter valid under
v0.2.0 remains valid, and the only edits to open-predicate-schema.json are two description
annotations and its version strings.
Added#
Per-field domains in the capability document. SPEC.md §2.2's RECOMMENDED shape now carries
type,format,valuesanddescriptionalongsideoperators, with a table defining each. The grammar cannot express per-field operand domains — every path shares oneConstraint— so a filter naming a real field with an out-of-domain value is well-formed and matches nothing. The capability document is the only place that domain can be stated.Recovery members on problem details. SPEC.md §8 now RECOMMENDS that
unknown-fieldcarryqueryableFieldsand thatinvalid-operandcarryaccepted, so a client that never fetched the capability document can still converge in one round trip instead of guessing field names one at a time.README §Exposing search to an agent — what reaches a tool definition, the three valid-but-wrong filters that fail as an empty result set, and the five steps that prevent them (bundle rather than remote-
$ref, narrowFieldPath, publish value domains, trim to advertised profiles, state the null and$insemantics in the tool description).tools/generate-filter-schema.mjs— derives a per-resource filter schema from the resource's own JSON Schema. The published grammar shares oneConstraintacross every field, so it can say{"status": "Available"}is well-formed but not that"Available"is outsidestatus's domain; that is why SPEC.md §2.2 exists. A generated schema gives each queryable path its own constraint subschema, carrying only the operators that apply to its type and only the operands its domain admits — so the three valid-but-wrong filters catalogued in README §Exposing search to an agent become validation failures instead of empty result sets. The generator emits the §2.2 capability document from the same source, and copies operator prose out of the published grammar rather than restating it. Generation is narrowing only: every filter a generated schema accepts is valid against the published grammar, whichtests/generator.test.mjsasserts.COMPARISON.md— how this specification relates to GraphQL, and what a JSON-Schema-native alternative to GraphQL would still need. The short version: GraphQL never standardised filtering, so the two overlap far less than the question assumes. Also covers OData, JSON:API, OGC CQL2 and JSON Hyper-Schema as prior art.examples/pet.schema.jsonwith its generatedpet.filter.jsonandpet.capabilities.jsoncommitted beside it, andnpm run generate:exampleto refresh them. A test fails if they drift.README §Generating a per-resource filter schema — what the generator decides and why, and the
x-open-predicateproperty annotations that override it.
Changed#
- README framing. The schema is presented as feeding two integration paths rather than
one:
$ref'd from an OpenAPI document, or bundled into an MCP tool'sinputSchema. The Referencing by URL or by copy table gains anMCP inputSchemarow recording that the absolute-URL form does not work there at all, since nothing on that path resolves remote refs. $inand$nindescriptions now state that they compare the whole value and do not test array membership, naming$hasAny/$hasNoneas the element operators.$containsalready warned about the same crossover; these two did not, and they are the operators a client carrying MongoDB habits reaches for first.$idis now…/v0.3.0/open-predicate-schema.json. Consumers pin by$id, so the version in the path moves with the release.SPEC.md, the OpenAPI examples and the generated capability document were all still naming v0.2.0; they now agree.- README §Status states that this is a work in progress, name included. The name is not
final, and every identifier downstream of it — both package names, the
$id, the URLs in the integration examples — is a placeholder, several of which do not resolve. Getting them right is deliberately deferred until the name is settled, because a rename moves all of them at once. A notice at the top of the README says the same thing before a reader reaches an install command that will not work. QUERYnow cites RFC 10008 rather thandraft-ietf-httpbis-safe-method-w-body. The method reached Proposed Standard in June 2026. The advice to shipPOST /searchalongside it is unchanged, but the reason is now that deployed support trails a fresh RFC, not that the specification is unsettled.
0.2.0 — 2026-08-06#
A structural rewrite. The v0.1.0 file described a grammar but did not enforce one; this
release makes it a working schema, fixes the grammar's dead ends, and completes the operator
set. Filters written against v0.1.0 still parse apart from the $isnull rename.
Fixed#
- The schema validated nothing. The root used
"id"(a draft-04 spelling) rather than"$id", and wrapped its definitions incomponents.schemas, which is an OpenAPI container and not a JSON Schema keyword. Under draft 2020-12 both were unknown keywords, and the root carried no assertion keywords at all — so a validator pointed at the file accepted every instance. The root now$refs#/$defs/Filter. "regex"is not a JSON Schema keyword (it is"pattern"), and the value it carried —"['\"%?.+%?['\"]"— was a malformed character class that also expected quote characters inside the operand.$likeand$nlikeare now plain strings; the wildcard and escape grammar is specified in prose (SPEC.md §5.5) where it belongs.exampleswas an object throughout, in the OpenAPI Example-Object style, where JSON Schema requires an array of instance values; two schemas used the OpenAPI 3.0 singularexample. Both spellings are now correct, and a test walks the whole document to keep them that way.- Operators from different families could not be combined on one field. The eight-way
oneOfover leaf condition types meant{"age": {"$gt": 18, "$ne": 30}}matched no branch and was rejected. Sibling operators now AND together. - Ambiguous and empty forms were accepted or accidentally rejected.
{}matched all eight leaf branches at once;{"$and": […], "$or": […]}was accepted with no defined semantics;$and: []and$in: []were accepted. Empty forms are now rejected, and implicit AND across siblings is specified. $in/$ninexcluded booleans andnullwhile$eqallowed them.
Changed — breaking#
| v0.1.0 | v0.2.0 | Note |
|---|---|---|
"id": "…/v0.1.0" | "$id": "…/v0.2.0/open-predicate-schema.json" | Correct keyword, versioned path |
#/components/schemas/Query | #/$defs/Filter | Or $ref the file itself |
#/components/schemas/Condition | (removed) | Folded into #/$defs/Filter |
#/components/schemas/equalCondition, notEqualCondition, inArrayCondition, notInArrayCondition, likeCondition, notLikeCondition, rangeCondition, isNullCondition | (removed) | Folded into #/$defs/ConstraintObject |
$isnull | $isNull | Renamed for consistency with $startsWith &c. |
Any OpenAPI document referencing a #/components/schemas/… pointer must be repointed. Filter
documents need no change other than $isnull → $isNull; the v0.1.0 examples are kept as
test fixtures to prove it.
Added#
- Operators.
$nor;$nbetween;$ilike,$nilike,$startsWith,$endsWith,$contains;$regexwith$flags;$exists;$type;$hasAny,$hasAll,$hasNone,$size,$elemMatch;$search; a field-level$not. - Field-to-field comparison via
{"$field": "path"}in operand position — SQL'sWHERE price > cost— with{"$literal": …}as the escape for object operands that would otherwise read as references. - Scalar shorthand.
{"status": "open"}for{"status": {"$eq": "open"}}. Restricted to strings, numbers, booleans andnull, so{"tags": ["a"]}can never be read ambiguously. null, arrays and objects as$eq/$neoperands.- A field path grammar — dotted paths, array indices,
[*]wildcards,\.dot escaping — and a rule for field names beginning with$: they are escaped by doubling ($$price). A single$prefix that is not a known operator is now rejected, so$eqqis an error rather than a field name. - Conformance profiles, published in the schema as
x-profilesand specified in SPEC.md §2.1, so a server can advertise the subset it implements. - One override point for the queryable field set,
#/$defs/FieldPath, reached throughpropertyNamesso that narrowing it in a bundled copy applies at every nesting level. - SPEC.md — three-valued logic, missing-versus-null, coercion rules, per-operator semantics, safety limits, and an RFC 9457 problem-type registry.
- README.md — operator reference and OpenAPI 3.1 / 3.2 integration guidance.
- Tests and CI — ajv under
strict: true, 30 valid and 22 invalid fixtures, and Redocly linting of both OpenAPI examples.
Notes#
$dynamicRef/$dynamicAnchor was evaluated as a way to let consumers restrict the queryable
field set without copying the file, and rejected: ajv 8.20 does not resolve it correctly even
for the canonical recursive case, and OpenAPI tooling support is worse. The $ref-based
override described in the README works in every validator.
0.1.0 — 2025-02-05#
Initial research draft: $and, $or, $not over eight leaf condition types
($eq, $ne, $in, $nin, $like, $nlike, $gt/$gte/$lt/$lte/$between, $isnull),
laid out as an OpenAPI components.schemas fragment.