[bugfix] External variable: supplied value overrides declared default#6475
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[bugfix] External variable: supplied value overrides declared default#6475joewiz wants to merge 2 commits into
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A value supplied for an external variable by the external environment must take precedence over the variable's declared default (XQuery 3.1 §4.15 External Variables). eXist evaluated the default unconditionally for a `declare variable $x external := ...` declaration, so a value bound via XQueryContext.declareVariable (XMLDB declareVariable, util:eval external vars, REST/API callers, etc.) was ignored whenever the declaration carried a default. VariableDeclaration now carries an `external` flag (set by the tree parser for `declare variable ... external`). On eval, an external declaration with a default first checks whether a value was supplied (a non-null global value already bound before execution) and, if so, uses it instead of evaluating the default. Behavior is unchanged for non-external globals, for external variables without a default, and for defaulted externals with no supplied value. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Adds a `variables` describe block to query.cy.js covering: scalar string binding; JSON number → xs:double; JSON array → array(*) (members via ?*); JSON object → map(*); a supplied name with no matching external declaration is ignored; and a missing required external returns an error. All use no-default externals, so the spec is independent of the eXist-core default-override fix (eXist-db/exist#6475). 37/37 green locally. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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| final XQueryService service = server.getRoot().getService(XQueryService.class); | ||
| try { | ||
| service.query("declare variable $required external; $required"); | ||
| org.junit.Assert.fail("expected XPDY0002 for an unbound external variable with no default"); |
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[This response was co-authored with Claude Code. -Joe]
Done — switched to import static org.junit.Assert.fail; and the short fail(...). Thanks for the review!
Addresses @line-o's review on PR eXist-db#6475. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
joewiz
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Adds a `variables` describe block to query.cy.js covering: scalar string binding; JSON number → xs:double; JSON array → array(*) (members via ?*); JSON object → map(*); a supplied name with no matching external declaration is ignored; and a missing required external returns an error. All use no-default externals, so the spec is independent of the eXist-core default-override fix (eXist-db/exist#6475). 37/37 green locally. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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[This PR was co-authored with Claude Code. -Joe]
What & why
A value supplied for an external variable by the external environment should take precedence over the variable's declared default value (XQuery 3.1 §4.15 External Variables: "If a value is supplied by the external environment for an external variable, that value is used; otherwise, if a default value is specified, the default is used.").
eXist evaluated the default unconditionally for a
declare variable $x external := …declaration, so a value bound before execution — viaXQueryContext.declareVariable(the XMLDBXQueryService.declareVariable,util:eval's external-variables argument, REST/API callers, etc.) — was silently ignored whenever the declaration carried a default. Only externals without a default honored a supplied value.How
VariableDeclarationwas constructed identically for a plain internal global (declare variable $x := …) and an external-with-default (declare variable $x external := …), soeval()couldn't tell them apart and always evaluated the initializer.XQueryTree.g) now marks the declaration as external via a newVariableDeclaration.setExternal(true).VariableDeclaration.eval(): for an external declaration with a default, it first checks whether a value was already supplied (a non-null global value bound before execution) and, if so, uses it (applying the declared sequence type) instead of evaluating the default.Behavior is unchanged for: non-external globals (always evaluate their initializer), external variables without a default, and defaulted externals with no supplied value.
Test plan
ExternalVariableDefaultOverrideTest(exist-core), 5 cases, all green locally:xs:integer21 → 42) overrides default; default used when not supplied; missing required external still raisesXPDY0002; a plain internal global with an initializer is unaffected.Motivation
Enables parameterized server-side queries (binding
$paramvalues at call time) over HTTP — e.g. an editor running a stored.xqagainst the database the waybasex -bname=valuedoes — without forcing query authors to drop default values from their external-variable declarations.