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feat(spanner): implement ToValue for str - #6087

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fornwall:tovalue-for-str
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feat(spanner): implement ToValue for str#6087
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fornwall:tovalue-for-str

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@fornwall fornwall commented Jul 17, 2026 •
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ToValue was implemented for &str but not for the unsized str, meaning that callers had to pass an extra reference (&"hello").

Fixes #6084.

@fornwall
feat(spanner): implement ToValue for str
4112ade 
ToValue was implemented for &str but not for the unsized str.

Callers had to pass an extra reference (&"hello") or allocate a String.

Signed-off-by: Fredrik Fornwall <fredrik@fornwall.net>
@fornwall
fornwall requested review from a team as code owners July 17, 2026 12:46
@product-auto-label product-auto-label Bot added the api: spanner Issues related to the Spanner API. label Jul 17, 2026
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gemini-code-assist Bot reviewed Jul 17, 2026
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Code Review

This pull request refactors the ToValue trait implementation for string types in the Spanner crate by implementing ToValue directly on str and delegating String and &str to it, alongside adding a new unit test. Feedback suggests using fully qualified path syntax (<str as ToValue>::to_value) in both implementations to avoid intermediate delegation steps, improve readability, and prevent potential infinite recursion from auto-ref coercion.

Comment thread src/spanner/src/to_value.rs Outdated
Comment thread src/spanner/src/to_value.rs Outdated
fornwall and others added 2 commits July 17, 2026 14:50
@fornwall @gemini-code-assist
Update src/spanner/src/to_value.rs
c7ca531 
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
@fornwall @gemini-code-assist
Update src/spanner/src/to_value.rs
14c34ad 
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
This was referenced Jul 27, 2026
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Open
olavloite added a commit to olavloite/google-cloud-rust that referenced this pull request Jul 27, 2026
@olavloite
feat(spanner): accept T: Into<Value> in parameter and mutation bindings
7151539 
Changes `StatementBuilder::add_param`, `StatementBuilder::add_typed_param`, and `ValueBinder::to` to accept `T: Into<Value>` instead of `&T: ToValue`.

This allows callers to pass owned values directly (like `String`, `Value`, or `Option<T>`) zero-copy without unnecessary cloning, while maintaining complete backward compatibility for references (`&str`, `&i64`, `&Option<T>`).

### Key Changes
- **Direct `From<T> for Value` Implementations**: Added zero-copy `From` conversions for owned types (`String`, `i64`, `i32`, `bool`, `f64`, `f32`, `Decimal`, `Date`, `OffsetDateTime`, `SystemTime`, `wkt::Timestamp`, `Vec<u8>`, `Option<T>`, `Vec<T>`, `ProtoValue`).
- **Decoupled `ToValue`**: All `ToValue` trait implementations now delegate directly to `From` / `.into()`, decoupling conversion logic from `ToValue` and paving the way for eventual deprecation of the `ToValue` trait.
- **Unsized Slice Support (`[u8]` and `str`)**: Implemented `ToValue` for `[u8]` and `str` (and `&[u8]`, `&str`), enabling zero-copy slice conversions and generic trait bounds `T: ToValue + ?Sized`. This supersedes both PR googleapis#6070 and PR googleapis#6087.
- **Untyped NULL Support**: Added `Value::null()`, `From<()>` and `ToValue for ()` to easily support untyped NULL parameters (`Value::null()`, `None::<()>`, `None::<Value>`).
- **Cleaned up Examples & Tests**: Updated example scripts and tests to pass owned values directly, eliminating needless reference borrows (`clippy::needless_borrows_for_generic_args`).

BREAKING CHANGE: This is a minor breaking change only for code that passes inline `&None` with a method-level turbofish:

```rust
// Old (fails to compile):
builder.set("Col").to::<Option<bool>>(&None);

// Works both before and after this change:
builder.set("Col").to(&None::<bool>);

// New (remove the &):
builder.set("Col").to::<Option<bool>>(None);
// Or:
builder.set("Col").to(None::<bool>);
builder.set("Col").to(Value::null());
```

Code passing existing `Option` variables (like `.to(&my_var)`) is unaffected and continues to compile unchanged.
olavloite added a commit to olavloite/google-cloud-rust that referenced this pull request Jul 27, 2026
@olavloite
feat(spanner): accept T: Into<Value> in parameter and mutation bindings
f078404 
Changes `StatementBuilder::add_param`, `StatementBuilder::add_typed_param`, and `ValueBinder::to` to accept `T: Into<Value>` instead of `&T: ToValue`.

This allows callers to pass owned values directly (like `String`, `Value`, or `Option<T>`) zero-copy without unnecessary cloning, while maintaining complete backward compatibility for references (`&str`, `&i64`, `&Option<T>`).

- **Direct `From<T> for Value` Implementations**: Added zero-copy `From` conversions for owned types (`String`, `i64`, `i32`, `bool`, `f64`, `f32`, `Decimal`, `Date`, `OffsetDateTime`, `SystemTime`, `wkt::Timestamp`, `Vec<u8>`, `Option<T>`, `Vec<T>`, `ProtoValue`).
- **Decoupled `ToValue`**: All `ToValue` trait implementations now delegate directly to `From` / `.into()`, decoupling conversion logic from `ToValue` and paving the way for eventual deprecation of the `ToValue` trait.
- **Unsized Slice Support (`[u8]` and `str`)**: Implemented `ToValue` for `[u8]` and `str` (and `&[u8]`, `&str`), enabling zero-copy slice conversions and generic trait bounds `T: ToValue + ?Sized`. This supersedes both PR googleapis#6070 and PR googleapis#6087.
- **Untyped NULL Support**: Added `Value::null()`, `From<()>` and `ToValue for ()` to easily support untyped NULL parameters (`Value::null()`, `None::<()>`, `None::<Value>`).
- **Cleaned up Examples & Tests**: Updated example scripts and tests to pass owned values directly, eliminating needless reference borrows (`clippy::needless_borrows_for_generic_args`).

BREAKING CHANGE: This is a minor breaking change only for code that passes inline `&None` with a method-level turbofish:

```rust
// Old (fails to compile):
builder.set("Col").to::<Option<bool>>(&None);

// Works both before and after this change:
builder.set("Col").to(&None::<bool>);

// New (remove the &):
builder.set("Col").to::<Option<bool>>(None);
// Or:
builder.set("Col").to(None::<bool>);
builder.set("Col").to(Value::null());
```

Code passing existing `Option` variables (like `.to(&my_var)`) is unaffected and continues to compile unchanged.
olavloite added a commit to olavloite/google-cloud-rust that referenced this pull request Jul 27, 2026
@olavloite
feat(spanner): accept T: Into<Value> in parameter and mutation bindings
b205c13 
Changes `StatementBuilder::add_param`, `StatementBuilder::add_typed_param`, and `ValueBinder::to` to accept `T: Into<Value>` instead of `&T: ToValue`.

This allows callers to pass owned values directly (like `String`, `Value`, or `Option<T>`) zero-copy without unnecessary cloning, while maintaining complete backward compatibility for references (`&str`, `&i64`, `&Option<T>`).

- **Direct `From<T> for Value` Implementations**: Added zero-copy `From` conversions for owned types (`String`, `i64`, `i32`, `bool`, `f64`, `f32`, `Decimal`, `Date`, `OffsetDateTime`, `SystemTime`, `wkt::Timestamp`, `Vec<u8>`, `Option<T>`, `Vec<T>`, `ProtoValue`).
- **Decoupled `ToValue`**: All `ToValue` trait implementations now delegate directly to `From` / `.into()`, decoupling conversion logic from `ToValue` and paving the way for eventual deprecation of the `ToValue` trait.
- **Unsized Slice Support (`[u8]` and `str`)**: Implemented `ToValue` for `[u8]` and `str` (and `&[u8]`, `&str`), enabling zero-copy slice conversions and generic trait bounds `T: ToValue + ?Sized`. This supersedes both PR googleapis#6070 and PR googleapis#6087.
- **Untyped NULL Support**: Added `Value::null()`, `From<()>` and `ToValue for ()` to easily support untyped NULL parameters (`Value::null()`, `None::<()>`, `None::<Value>`).
- **Cleaned up Examples & Tests**: Updated example scripts and tests to pass owned values directly, eliminating needless reference borrows (`clippy::needless_borrows_for_generic_args`).

BREAKING CHANGE: This is a minor breaking change only for code that passes inline `&None` with a method-level turbofish:

```rust
// Old (fails to compile):
builder.set("Col").to::<Option<bool>>(&None);

// Works both before and after this change:
builder.set("Col").to(&None::<bool>);

// New (remove the &):
builder.set("Col").to::<Option<bool>>(None);
// Or:
builder.set("Col").to(None::<bool>);
builder.set("Col").to(Value::null());
```

Code passing existing `Option` variables (like `.to(&my_var)`) is unaffected and continues to compile unchanged.
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spanner: impl ToValue for str

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