Make duckdb connection string support unicode path

[Cricle]

Fix #196

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 88.48%. Comparing base (c6437cc) to head (9b924f6). Report is 27 commits behind head on develop.

Files	Patch %	Lines
...ET.Bindings/NativeMethods/NativeMethods.Startup.cs	60.00%	3 Missing and 1 partial :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #197 +/- ## =========================================== + Coverage 88.38% 88.48% +0.10% =========================================== Files 54 57 +3 Lines 1756 1841 +85 Branches 239 254 +15 =========================================== + Hits 1552 1629 +77 - Misses 146 153 +7 - Partials 58 59 +1 ```

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[coveralls]

Pull Request Test Coverage Report for Build 9515547530

Details

• 7 of 10 (70.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 90.435%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
DuckDB.NET.Bindings/NativeMethods/NativeMethods.Startup.cs	7	10	70.0%
<!--	Total:	7	10	70.0%	-->

Totals
Change from base Build 9511955148:	-0.1%
Covered Lines:	1688
Relevant Lines:	1841

---

💛 - Coveralls

[Cricle]

I think the logic for converting string to handle belongs to the Data project. The Bindings project should contain only method definitions

The NativeMethods.Startup.DuckDBOpen will be a breakchang

[Giorgi]

You don't need to delete existing methods, just add a new overload.

[Cricle]

If I make it overload method, can accept it?

NativeMethods.Startup.DuckDBOpen(null,out _);//<--- compile error, because the compiler unable to decide what method to execute.

[Giorgi]

You can cast null to the desired type to help the compiler.

[Cricle]

What about that?

[DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_open")]
public static extern DuckDBState DuckDBOpen(SafeUnmanagedMemoryHandle path, out DuckDBDatabase database);

[DllImport(DuckDbLibrary, CallingConvention = CallingConvention.Cdecl, EntryPoint = "duckdb_open")]
public static extern DuckDBState DuckDBOpen(string? path, out DuckDBDatabase database);

//Usage
NativeMethods.Startup.DuckDBOpen((string?)null,out _);

[Giorgi]

That should work.

[Cricle]

Completed

[Giorgi]

You should not put logic in NativeMethods.Startup, just new overloads and call the correct one from the Data project.

[Cricle]

I may not quite understand what you mean, can you explain it in detail?

I know

[Giorgi]

Yeah, that's what I meant.