fix(model): guard the scope dereference in validatesUniquenessOf

`validatesUniquenessOf(property="x", scope="y")` threw

  Component [MyModel] has no accessible Member with name [y]

whenever `y` had never been assigned — out of a method whose entire job is to return a
validation result. A caller that correctly wraps `save()` in an `if` still got an exception,
and it surfaced as a 500.

`$buildWhereClausePart()` read `this[arguments.property]` with no existence guard. That is
easy to hit because absent and empty are different states here: `$setDefaultValues()` only
seeds properties that have an explicit `property()` mapping, so a column with a
database-level default but no mapping is missing from a `new()`-ed object rather than
present-and-blank. The `scope=` in the model source looks fine; nothing in it hints that the
property will be absent at validation time.

Only scopes were exposed. The validated property itself cannot reach this code absent —
`$shouldInvokeValidation()` returns false when it is missing from the object — which is why
the split went unnoticed: "unset" and "set to empty" produced an exception and a validation
result respectively, for the same logical state.

An absent scope property is now treated as blank, so both states take the identical path,
including the existing conversion of an empty numeric scope to `IS NULL`. The guard mirrors
`validationTypeForProperty()` and `key()` in the same layer, which already read optional
properties this way.

Red-first: 945 pass / 0 fail / 2 errors, both errors being the reported message verbatim
against the existing `CombiKey` fixture (`validatesUniquenessOf(property="id1",
scope="id2")`).

Verification, lucee7 + sqlite, full core suite:

  develop ab901cf   4732 pass / 0 fail / 0 error
  this branch         4734 pass / 0 fail / 0 error

Exactly +2, the new specs.

Closes #3350

Signed-off-by: Peter Amiri <peter@alurium.com>

Author: bpamiri

changelog.d/3350-uniqueness-scope-guard.fixed.md

@@ -0,0 +1 @@
+- `validatesUniquenessOf(property="x", scope="y")` now returns a validation result instead of throwing `Component [Model] has no accessible Member with name [y]` when the scope property was never assigned. Building the uniqueness `WHERE` clause dereferenced every scope property without an existence guard, and a scope property is easy to leave absent rather than empty: `$setDefaultValues()` only seeds properties with an explicit `property()` mapping, so a column with a database-level default but no mapping is missing from a `new()`-ed object entirely. An absent scope property is now treated as blank, matching what a present-but-empty one has always done — including the existing conversion of an empty numeric scope to `IS NULL`. The `property(name="<scopeProperty>", defaultValue="")` workaround is no longer needed (#3350)

public/testbox/system/stubs/F952D54F1096E25C030C8E3149ABD8C4.cfm

@@ -783,8 +783,18 @@ component {
 	 * and converting blank numeric properties to IS NULL.
 	 */
 	public string function $buildWhereClausePart(required string property) {
+		// A property named in `scope=` may be absent rather than empty: `$setDefaultValues()`
+		// only seeds properties with an explicit `property()` mapping, so a column that has a
+		// database-level default but no mapping never appears on a `new()`-ed object. Reading
+		// it unguarded threw "has no accessible Member" out of a validation, so an absent
+		// scope property produced an exception where a blank one produced a validation result
+		// (issue #3350). The validated property itself cannot be absent here —
+		// `$shouldInvokeValidation()` skips the validation in that case — so this guard only
+		// ever fires for scopes. Treat absent as blank, which is the branch below that turns
+		// an empty numeric into `IS NULL`.
+		local.value = StructKeyExists(this, arguments.property) ? this[arguments.property] : "";
 		local.part = arguments.property & "=" & variables.wheels.class.adapter.$quoteValue(
-			str = this[arguments.property],
+			str = local.value,
 			type = validationTypeForProperty(arguments.property)
 		);
 		if (Right(local.part, 3) == "=''" && ListFindNoCase("integer,float,boolean", validationTypeForProperty(arguments.property))) {

vendor/wheels/model/validations.cfc

@@ -1015,6 +1015,32 @@ component extends="wheels.WheelsTest" {
 				expect(combiKey.valid()).toBeFalse()
 			})
 
+			// Issue #3350: a property named in `scope=` that was never assigned is ABSENT
+			// from the object, not present-and-empty — `$setDefaultValues()` only seeds
+			// properties with an explicit `property()` mapping. The scope dereference had no
+			// existence guard, so building the uniqueness WHERE clause threw
+			// "Component [X] has no accessible Member with name [Y]" out of a method whose
+			// entire job is to return a validation result. The validated property itself
+			// cannot hit this — `$shouldInvokeValidation()` skips the validation when it is
+			// absent — so only `scope=` was exposed.
+			it("validatesUniquenessOf_with_absent_scope_property", () => {
+				combiKey = g.model("combiKey").new(id1 = 1, id2 = 1)
+				StructDelete(combiKey, "id2")
+
+				// must return a validation result rather than throwing
+				expect(combiKey.valid()).toBeFalse()
+			})
+
+			// An absent scope property must behave exactly like a present-but-empty one —
+			// the split between the two was the defect, not the value itself.
+			it("validatesUniquenessOf_absent_scope_matches_blank_scope", () => {
+				absent = g.model("combiKey").new(id1 = 1, id2 = "")
+				StructDelete(absent, "id2")
+				blank = g.model("combiKey").new(id1 = 1, id2 = "")
+
+				expect(absent.$buildWhereClausePart("id2")).toBe(blank.$buildWhereClausePart("id2"))
+			})
+
 			it("validatesUniquenessOf_with_blank_property_value", () => {
 				user.blank = ""
 				user.validatesUniquenessOf(properties = "blank")