Default EnableCaseInsensitive to true when initializing a new instance of ODataUriResolver

[gathogojr]

Issues

This pull request fixes #3066.

Description

This pull request addresses #3066 by aligning the default behavior of ODataUriResolver with the OData V4.01 specification.

According to the OData V4.01 specification, services MUST support case-insensitive system query option names, whether or not they are prefixed with $.

ASP.NET Core OData already complies with this requirement by injecting a case-insensitive UnqualifiedODataUriResolver (derived from ODataUriResolver) by default:
https://github.com/OData/AspNetCoreOData/blob/1368836752963d88e920d9508d94807eb995894b/src/Microsoft.AspNetCore.OData/ODataOptions.cs#L326-L329

To ensure consistent behavior across the OData ecosystem, this PR proposes setting EnableCaseInsensitive = true by default when initializing a new instance of ODataUriResolver in ODL:

odata.net/src/Microsoft.OData.Core/UriParser/Resolver/ODataUriResolver.cs

Line 24 in 95233fc

private static readonly ODataUriResolver Default = new ODataUriResolver();

With this change, both of the following requests will be parsed successfully and equivalently:

GET https://localhost:54001/odata/Books?$expand=Authors

GET https://localhost:54001/odata/Books?$expand=authors

This change improves spec compliance and developer experience by reducing case-sensitivity issues in query options.

Checklist (Uncheck if it is not completed)

• Test cases added
• Build and test with one-click build and test script passed

Additional work necessary

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[xuzhg]

From your notes in the PR, it says that the case insensitive for the query options key name no matter whether it prefixes with '$', Is it right?

Here, if we default to 'true', it means all the Uri parts are case insensitive by default?

[gathogojr]

@xuzhg That statement is directly from the standard: OData V4.01 states that services MUST support case-insensitive system query option names specified with or without the $ prefix.

With this change, the URI parts are case-insensitive by default - which is what the UnqualifiedODataUriResolver does in ASP.NET Core OData here:
https://github.com/OData/AspNetCoreOData/blob/1368836752963d88e920d9508d94807eb995894b/src/Microsoft.AspNetCore.OData/ODataOptions.cs#L326

[CAPCHIK]

Hi @gathogojr,

Could you clarify why this MR changes the handling of property names? The standard specifies that query parameter names (like $expand) should be case-insensitive, but not their values. For example, $exand and $EXPand should be treated as equivalent, but $expand=shoe and $expand=Shoe should not.

This has been a pain point for me regarding case insensitivity—especially since C# class properties are also resolved in a case-insensitive manner, though I haven’t found a clear justification for it. (Related PR where I struggled to write tests)

Could you explain why property names should be handled case-insensitively?

[WanjohiSammy]

I thought this was already true by default.

Could you add a test that makes this to false.

[gathogojr]

@WanjohiSammy The default was false, as you can see from the following tests:

For the UnqualifiedODataUriResolver in ASP.NET Core OData here
https://github.com/OData/AspNetCoreOData/blob/1368836752963d88e920d9508d94807eb995894b/src/Microsoft.AspNetCore.OData/ODataOptions.cs#L326, we set it to true to support case insensitive behaviour when resolving OData URIs.

Regarding your ask, do you need me to add a test like the following:

        [Fact]
        public void TestEnableCaseInsensitiveBuiltinIdentifierSetToFalse()
        {
            Assert.False((new ODataUriResolver { EnableCaseInsensitive = false }).EnableCaseInsensitive);
        }

[WanjohiSammy]

Something like this will suffice