Struct QueryScalar 

pub struct QueryScalar { /* private fields */ }

Execute a SELECT query and return a single scalar value.

The query must return exactly one row with one column.

Examples

use ironflow_ops_postgres::query::QueryScalar;
use ironflow_core::operation::Operation;

let op = QueryScalar::new(pool, "SELECT count(*) FROM users", vec![]);
assert_eq!(op.kind(), "postgres");

Implementations

impl QueryScalar

pub fn new(pool: PgPool, sql: impl Into<String>, params: Vec<Value>) -> Self

Create a new query-scalar operation.

pub async fn run( &self, _ctx: &OperationContext, ) -> Result<QueryScalarOutput, OperationError>

Execute and return a typed result.

Errors

Returns OperationError::External on SQL/connection errors or if the query does not return exactly one row with one column.

Trait Implementations

impl Operation for QueryScalar

fn kind(&self) -> &str

A short, lowercase identifier for this operation type.

fn execute<'life0, 'life1, 'async_trait>( &'life0 self, ctx: &'life1 OperationContext, ) -> Pin<Box<dyn Future<Output = Result<Value, OperationError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Execute the operation and return the result as JSON.

fn input(&self) -> Option<Value>

Optional JSON representation of the operation input, stored in the step’s input column for observability.

impl TypedOperation for QueryScalar

type Output = QueryScalarOutput

The concrete output type that Operation::execute produces.