Trait Connection 

pub trait Connection: Send + Sync
where
    for<'c> &'c mut <Self::DB as Database>::Connection: Executor<'c, Database = Self::DB>,
    usize: ColumnIndex<<Self::DB as Database>::Row>,
    <Self::DB as Database>::Row: RowExt,
    <Self::DB as Database>::QueryResult: QueryResult,
{
    type DB: Database;

    // Required methods
    async fn pool(
        &self,
        target: Option<&str>,
    ) -> Result<Pool<Self::DB>, SqlError>;
    fn query_timeout(&self) -> Option<u64>;

    // Provided methods
    async fn execute<'q, E>(
        &self,
        query: E,
        database: Option<&str>,
    ) -> Result<u64, SqlError>
       where E: 'q + Execute<'q, Self::DB> { ... }
    async fn fetch_json<'q, E>(
        &self,
        query: E,
        database: Option<&str>,
    ) -> Result<Vec<Value>, SqlError>
       where E: 'q + Execute<'q, Self::DB> { ... }
    async fn fetch_optional<'q, E, T>(
        &self,
        query: E,
        database: Option<&str>,
    ) -> Result<Option<T>, SqlError>
       where E: 'q + Execute<'q, Self::DB>,
             T: for<'r> Decode<'r, Self::DB> + Type<Self::DB> + Send + Unpin { ... }
    async fn fetch_scalar<'q, E, T>(
        &self,
        query: E,
        database: Option<&str>,
    ) -> Result<Vec<T>, SqlError>
       where E: 'q + Execute<'q, Self::DB>,
             T: for<'r> Decode<'r, Self::DB> + Type<Self::DB> + Send + Unpin { ... }
    async fn fetch<'q, E, T>(
        &self,
        query: E,
        database: Option<&str>,
    ) -> Result<Vec<T>, SqlError>
       where E: 'q + Execute<'q, Self::DB>,
             T: for<'r> FromRow<'r, <Self::DB as Database>::Row> + Send + Unpin { ... }
}

Unified query surface every backend tool handler uses.

Backends supply three required items — DB, pool, and query_timeout — and receive default implementations for query execution.

Query methods accept any sqlx::Execute value: a plain &str for bindless statements (which routes through sqlx’s unprepared text protocol, required for statements like MySQL USE), or an sqlx::query(sql).bind(...) value for parameterized statements.

Errors

Query methods may return:

• SqlError::InvalidIdentifier — database failed identifier validation.
• [SqlError::Connection] — the underlying driver failed.
• SqlError::QueryTimeout — the query exceeded the configured timeout.

Required Associated Types

type DB: Database

The sqlx database driver type (e.g. sqlx::MySql).

Required Methods

async fn pool(&self, target: Option<&str>) -> Result<Pool<Self::DB>, SqlError>

Resolves the connection pool for the given target database.

Errors

• SqlError::InvalidIdentifier — target failed validation.

fn query_timeout(&self) -> Option<u64>

Returns the configured query timeout in seconds, if any.

Provided Methods

async fn execute<'q, E>( &self, query: E, database: Option<&str>, ) -> Result<u64, SqlError>

where E: 'q + Execute<'q, Self::DB>,

Runs a statement that returns no meaningful rows.

Errors

See trait-level documentation.

async fn fetch_json<'q, E>( &self, query: E, database: Option<&str>, ) -> Result<Vec<Value>, SqlError>

where E: 'q + Execute<'q, Self::DB>,

Runs a statement and collects every result row as JSON.

Errors

See trait-level documentation.

async fn fetch_optional<'q, E, T>( &self, query: E, database: Option<&str>, ) -> Result<Option<T>, SqlError>

where E: 'q + Execute<'q, Self::DB>, T: for<'r> Decode<'r, Self::DB> + Type<Self::DB> + Send + Unpin,

Runs a query and extracts column 0 from the first row, if any.

Returns None for both “no row returned” and “row where column 0 is NULL” (decode errors are caught, not propagated).

Errors

See trait-level documentation.

async fn fetch_scalar<'q, E, T>( &self, query: E, database: Option<&str>, ) -> Result<Vec<T>, SqlError>

where E: 'q + Execute<'q, Self::DB>, T: for<'r> Decode<'r, Self::DB> + Type<Self::DB> + Send + Unpin,

Runs a query and extracts the first column of every row.

Errors

See trait-level documentation.

async fn fetch<'q, E, T>( &self, query: E, database: Option<&str>, ) -> Result<Vec<T>, SqlError>

where E: 'q + Execute<'q, Self::DB>, T: for<'r> FromRow<'r, <Self::DB as Database>::Row> + Send + Unpin,

Runs a query and decodes every row into T via sqlx::FromRow.

Errors

See trait-level documentation. Row decode failures (column type mismatch, malformed JSON inside a sqlx::types::Json column, etc.) surface as SqlError::Query.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors