Fixes #57637 [FromQuery] Model binding fails in case of propertity with…

[FatTigerWang]

… the same name

Fixes #57637 [FromQuery] Model binding fails

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Summary

Note: This PR was generated with AI assistance.

Fix #57637 — [FromQuery] model binding fails when the parameter name matches a property name of the complex type model.

Root cause: In ParameterBinder.cs, ContainsPrefix(parameter.Name) returns true on a case-insensitive exact match (e.g., query key "Parameter" matches parameter name "parameter"). This incorrectly sets the model prefix to "parameter", causing the complex type binder to look for "parameter.Parameter" instead of just "Parameter".

Fix: For complex types, after ContainsPrefix returns true, additionally verify via GetKeysFromPrefix() that delimiter-separated sub-keys exist. If none exist (only an exact name match), fall back to empty prefix so properties bind directly.

Changes

• src/Mvc/Mvc.Core/src/ModelBinding/ParameterBinder.cs — Added complex type check to distinguish property name collisions from true prefix matches
• src/Mvc/Mvc.Core/test/ModelBinding/ParameterBinderTest.cs — Added 3 unit tests covering the fix, prefix usage, and simple type behavior

Test Plan

• Complex type with property name collision (?Parameter=test) binds correctly with empty prefix
• Explicit prefix usage (?parameter.Parameter=test) still uses parameter name as prefix
• Simple types are unaffected by the change

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Thanks for your PR, @FatTigerWang. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.