google-cloud-spanner 0.34.2-preview

// Copyright 2026 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

pub use crate::types::{Type, TypeCode};
use crate::value::Kind;
use crate::value::Value;
use base64::Engine;
use base64::prelude::BASE64_STANDARD;
use rust_decimal::Decimal;
use std::time::SystemTime;
use time::{Date, OffsetDateTime};

/// Represent failures in converting a Spanner Value to a Rust type.
#[derive(thiserror::Error, Debug)]
#[non_exhaustive]
pub enum ConvertError {
    /// The value kind is not as expected.
    #[error("expected {want:?}, got {got:?}")]
    KindMismatch {
        /// The expected Spanner value kind.
        want: Kind,
        /// The actual Spanner value kind.
        got: Kind,
    },

    /// The value is null, but the target type does not support nulls.
    #[error("expected non-null value, got null")]
    NotNull,

    /// There was a problem during conversion.
    #[error("cannot convert value, source={0}")]
    Convert(#[source] BoxedError),
}

type BoxedError = Box<dyn std::error::Error + Send + Sync>;

/// Converts a Spanner [Value] into a Rust type.
///
/// Implementations are provided for all standard types like `String`, primitive integer
/// and float types, decimals, timestamps, dates, vectors, and options for nullable fields.
pub trait FromValue: Sized {
    /// Converts a Spanner value into the target Rust type, using the provided
    /// Spanner `Type` metadata for compatibility checks.
    ///
    /// # Errors
    ///
    /// Returns a [`ConvertError`] if the kind of the value does not match the expected kind,
    /// if the value is null but the target type is not optional (e.g., `Option<T>`), or if
    /// parsing or decoding the inner value format fails.
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError>;
}

impl<T> FromValue for Option<T>
where
    T: FromValue,
{
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::NullValue(_)) => Ok(None),
            _ => T::from_value(value, type_).map(Some),
        }
    }
}

impl FromValue for Value {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        Ok(value.clone())
    }
}

impl FromValue for String {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => Ok(s.clone()),
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for i64 {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                s.parse().map_err(|e| ConvertError::Convert(Box::new(e)))
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for i32 {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                s.parse().map_err(|e| ConvertError::Convert(Box::new(e)))
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for Decimal {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        if type_.code() != TypeCode::Numeric {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            });
        }
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                Decimal::from_str_exact(s).map_err(|e| ConvertError::Convert(Box::new(e)))
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for SystemTime {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        if type_.code() != TypeCode::Timestamp {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            });
        }
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                let dt = OffsetDateTime::parse(s, &time::format_description::well_known::Rfc3339)
                    .map_err(|e| ConvertError::Convert(Box::new(e)))?;
                Ok(dt.into())
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for OffsetDateTime {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        if type_.code() != TypeCode::Timestamp {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            });
        }
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                let dt = OffsetDateTime::parse(s, &time::format_description::well_known::Rfc3339)
                    .map_err(|e| ConvertError::Convert(Box::new(e)))?;
                Ok(dt)
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for wkt::Timestamp {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        let dt = OffsetDateTime::from_value(value, type_)?;
        wkt::Timestamp::try_from(dt).map_err(|e| ConvertError::Convert(Box::new(e)))
    }
}

impl FromValue for Date {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        if type_.code() != TypeCode::Date {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            });
        }
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => {
                let date = Date::parse(s, crate::value::SPANNER_DATE_FORMAT)
                    .map_err(|e| ConvertError::Convert(Box::new(e)))?;
                Ok(date)
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for bool {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::BoolValue(b)) => Ok(*b),
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::Bool,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for f64 {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::NumberValue(n)) => Ok(*n),
            Some(prost_types::value::Kind::StringValue(s)) => {
                s.parse().map_err(|e| ConvertError::Convert(Box::new(e)))
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::Number,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for f32 {
    fn from_value(value: &Value, _type: &Type) -> Result<Self, ConvertError> {
        match &value.0.kind {
            Some(prost_types::value::Kind::NumberValue(n)) => Ok(*n as f32),
            Some(prost_types::value::Kind::StringValue(s)) => {
                s.parse().map_err(|e| ConvertError::Convert(Box::new(e)))
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::Number,
                got: value.kind(),
            }),
        }
    }
}

impl FromValue for Vec<u8> {
    fn from_value(value: &Value, type_: &Type) -> Result<Self, ConvertError> {
        if type_.code() != TypeCode::Bytes && type_.code() != TypeCode::Proto {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            });
        }
        match &value.0.kind {
            Some(prost_types::value::Kind::StringValue(s)) => BASE64_STANDARD
                .decode(s)
                .map_err(|e| ConvertError::Convert(Box::new(e))),
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::String,
                got: value.kind(),
            }),
        }
    }
}

impl<T> FromValue for Vec<T>
where
    T: FromValue,
{
    fn from_value(value: &Value, r#type: &Type) -> Result<Self, ConvertError> {
        if r#type.code() != TypeCode::Array {
            return Err(ConvertError::KindMismatch {
                want: crate::value::Kind::List,
                got: value.kind(),
            });
        }
        let element_type = r#type
            .array_element_type()
            .ok_or_else(|| ConvertError::Convert("Array type missing element type".into()))?;

        match &value.0.kind {
            Some(prost_types::value::Kind::ListValue(list)) => {
                let mut vec = Vec::with_capacity(list.values.len());
                for v in &list.values {
                    // `Value` is a `#[repr(transparent)]` wrapper around `ProtoValue`.
                    // We use `from_ref` to safely cast the pointer and avoid cloning elements.
                    let val = crate::value::Value::from_ref(v);
                    vec.push(T::from_value(val, &element_type)?);
                }
                Ok(vec)
            }
            Some(prost_types::value::Kind::NullValue(_)) => Err(ConvertError::NotNull),
            _ => Err(ConvertError::KindMismatch {
                want: crate::value::Kind::List,
                got: value.kind(),
            }),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::to_value::ToValue;
    use crate::types;

    #[test]
    fn test_from_value_string() {
        let v = "hello".to_value();
        let s = String::from_value(&v, &types::string()).unwrap();
        assert_eq!(s, "hello");
    }

    #[test]
    fn test_from_value_int() {
        let v = 42i64.to_value();
        let i = i64::from_value(&v, &types::int64()).unwrap();
        assert_eq!(i, 42);

        let v = 42i32.to_value();
        let i = i32::from_value(&v, &types::int64()).unwrap();
        assert_eq!(i, 42);

        // Negative tests
        let v = "not an int".to_value();
        let err = i64::from_value(&v, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));

        let v = "not an int".to_value();
        let err = i32::from_value(&v, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_float() {
        let v = 42.5f64.to_value();
        let f = f64::from_value(&v, &types::float64()).unwrap();
        assert_eq!(f, 42.5);

        let v = "Infinity".to_string().to_value();
        let f = f64::from_value(&v, &types::float64()).unwrap();
        assert_eq!(f, f64::INFINITY);

        let v = "invalid float".to_string().to_value();
        let err = f64::from_value(&v, &types::float64()).unwrap_err();
        assert!(format!("{}", err).contains("invalid float literal"));
    }

    #[test]
    fn test_from_value_bool() {
        let v = true.to_value();
        let b = bool::from_value(&v, &types::bool()).unwrap();
        assert!(b);
    }

    #[test]
    fn test_from_value_array() {
        // String array
        let str_array = vec!["one".to_string(), "two".to_string()];
        let v = str_array.to_value();
        let res = Vec::<String>::from_value(&v, &types::array(types::string()))
            .expect("parsed string array");
        assert_eq!(res, str_array);

        // Int array
        let int_array = vec![42i64, 100i64];
        let v = int_array.to_value();
        let res =
            Vec::<i64>::from_value(&v, &types::array(types::int64())).expect("parsed int array");
        assert_eq!(res, int_array);

        // Bool array
        let bool_array = vec![true, false];
        let v = bool_array.to_value();
        let res =
            Vec::<bool>::from_value(&v, &types::array(types::bool())).expect("parsed bool array");
        assert_eq!(res, bool_array);

        // Float array
        let float_array = vec![9.9f64, -2.5f64];
        let v = float_array.to_value();
        let res = Vec::<f64>::from_value(&v, &types::array(types::float64()))
            .expect("parsed float array");
        assert_eq!(res, float_array);

        // Empty array
        let empty_array: Vec<f64> = vec![];
        let v = empty_array.to_value();
        let res = Vec::<f64>::from_value(&v, &types::array(types::float64()))
            .expect("parsed empty array");
        assert_eq!(res, empty_array);

        // Array with nulls
        let opt_array: Vec<Option<i64>> = vec![Some(42), None, Some(100)];
        let v = opt_array.to_value();
        let res = Vec::<Option<i64>>::from_value(&v, &types::array(types::int64()))
            .expect("parsed optional array");
        assert_eq!(res, opt_array);

        // Null array entirely
        let null_array: Option<Vec<i64>> = None;
        let v = null_array.to_value();
        let res = Option::<Vec<i64>>::from_value(&v, &types::array(types::int64()))
            .expect("parsed null array");
        assert_eq!(res, null_array);

        // Wrong TypeCode test
        let err = Vec::<i64>::from_value(&int_array.to_value(), &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected List"));

        // Invalid array element values
        let err = Vec::<i64>::from_value(&str_array.to_value(), &types::array(types::int64()))
            .unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value, source="));
    }

    #[test]
    fn test_from_value_bytes() {
        let bytes: Vec<u8> = vec![1, 2, 3];
        let v = bytes.to_value();
        let b = Vec::<u8>::from_value(&v, &types::bytes()).unwrap();
        assert_eq!(b, bytes);

        let v = "invalid base64".to_string().to_value();
        let err = Vec::<u8>::from_value(&v, &types::bytes()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_decimal() {
        let d = Decimal::from_str_exact("123.456").unwrap();
        let v = d.to_value();
        let res = Decimal::from_value(&v, &types::numeric()).unwrap();
        assert_eq!(res, d);

        let v = "invalid decimal".to_string().to_value();
        let err = Decimal::from_value(&v, &types::numeric()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_date() {
        let d = Date::from_calendar_date(2023, time::Month::October, 27).unwrap();
        let v = d.to_value();
        let res = Date::from_value(&v, &types::date()).unwrap();
        assert_eq!(res, d);

        let v = "invalid date".to_string().to_value();
        let err = Date::from_value(&v, &types::date()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_timestamp() {
        let dt = OffsetDateTime::parse(
            "2023-10-27T10:00:00Z",
            &time::format_description::well_known::Rfc3339,
        )
        .unwrap();
        let v = dt.to_value();
        let res = OffsetDateTime::from_value(&v, &types::timestamp()).unwrap();
        assert_eq!(res, dt);

        let v = "invalid timestamp".to_string().to_value();
        let err = OffsetDateTime::from_value(&v, &types::timestamp()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_null() {
        let v = Option::<i32>::None.to_value();
        let res = Option::<i32>::from_value(&v, &types::int64()).unwrap();
        assert_eq!(res, None);

        let v = Option::<i32>::None.to_value();
        let err = i32::from_value(&v, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));
    }
    #[test]
    fn test_from_value_system_time() {
        let dt = OffsetDateTime::parse(
            "2023-10-27T10:00:00Z",
            &time::format_description::well_known::Rfc3339,
        )
        .unwrap();
        let system_time: SystemTime = dt.into();
        let v = system_time.to_value();
        let res = SystemTime::from_value(&v, &types::timestamp()).unwrap();
        let res_dt: OffsetDateTime = res.into();
        assert_eq!(res_dt, dt);

        let v = "invalid timestamp".to_string().to_value();
        let err = SystemTime::from_value(&v, &types::timestamp()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_wkt_timestamp() {
        let dt = OffsetDateTime::parse(
            "2023-10-27T10:00:00Z",
            &time::format_description::well_known::Rfc3339,
        )
        .expect("valid date time parsing");
        let wkt_ts = wkt::Timestamp::try_from(dt).expect("valid wkt timestamp conversion");
        let v = dt.to_value();
        let res = wkt::Timestamp::from_value(&v, &types::timestamp())
            .expect("valid wkt timestamp decoding");
        assert_eq!(res, wkt_ts);

        let v = "invalid timestamp".to_string().to_value();
        let err = wkt::Timestamp::from_value(&v, &types::timestamp()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));
    }

    #[test]
    fn test_from_value_type_mismatch() {
        let v = Decimal::from(42).to_value();
        let err = Decimal::from_value(&v, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got String"));

        let v = SystemTime::now().to_value();
        let err = SystemTime::from_value(&v, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got String")); // This might require adjustment as logic changed. In `SystemTime::from_value`, we check TypeCode first.

        let v = OffsetDateTime::now_utc().to_value();
        let err = OffsetDateTime::from_value(&v, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got String"));

        let v = Date::from_calendar_date(2023, time::Month::October, 27)
            .unwrap()
            .to_value();
        let err = Date::from_value(&v, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got String"));

        let v = vec![1u8].to_value();
        let err = Vec::<u8>::from_value(&v, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got String"));
    }

    #[test]
    fn test_from_value_wrong_kind() {
        let v_bool = true.to_value();
        let err = String::from_value(&v_bool, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got Bool"));

        let v_string = "hello".to_value();
        let err = i64::from_value(&v_string, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("cannot convert value"));

        let v_struct = crate::value::Value(prost_types::Value {
            kind: Some(prost_types::value::Kind::StructValue(
                prost_types::Struct::default(),
            )),
        });
        let err = i64::from_value(&v_struct, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got Struct"));

        let err = f64::from_value(&v_bool, &types::float64()).unwrap_err();
        assert!(format!("{}", err).contains("expected Number, got Bool"));

        let err = bool::from_value(&v_string, &types::bool()).unwrap_err();
        assert!(format!("{}", err).contains("expected Bool, got String"));
    }

    #[test]
    fn test_from_value_null_errors() {
        let v_null = Option::<i32>::None.to_value();

        let err = String::from_value(&v_null, &types::string()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = i64::from_value(&v_null, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = f64::from_value(&v_null, &types::float64()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = f32::from_value(&v_null, &types::float32()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = bool::from_value(&v_null, &types::bool()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = Decimal::from_value(&v_null, &types::numeric()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = SystemTime::from_value(&v_null, &types::timestamp()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = OffsetDateTime::from_value(&v_null, &types::timestamp()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = Date::from_value(&v_null, &types::date()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));

        let err = Vec::<u8>::from_value(&v_null, &types::bytes()).unwrap_err();
        assert!(format!("{}", err).contains("expected non-null value, got null"));
    }

    #[test]
    fn test_from_value_option_missing_kind() {
        let v = crate::value::Value(prost_types::Value { kind: None });
        let err = Option::<i32>::from_value(&v, &types::int64()).unwrap_err();
        assert!(format!("{}", err).contains("expected String, got Null"));
    }
}