datasources 0.1.23

Async datasource interfaces, middleware, registry, and test doubles
Documentation 
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use crate::command_middleware::CommandMiddleware;
use crate::from_schema::FromSchema;
use crate::i_repository::IRepository;
use crate::IWhere;
use crate::id_key::IdKey;
use crate::read_input::ReadInput;
use crate::response::Response;
use crate::result::Result;
use crate::row::Row;
use crate::schema::Schema;
use async_trait::async_trait;
use futures_core::Stream;
use futures_util::StreamExt;
use std::any::TypeId;
use std::pin::Pin;
use std::sync::Arc;

#[async_trait]
pub trait IReadonlyRepository<T: FromSchema = Row>: IRepository {
    fn is_schema_required(&self) -> bool {
        true
    }

    fn to_crud(self: Arc<Self>) -> Option<Arc<dyn ICRUDRepository<T>>>
    where
        Self: Sized,
    {
        None
    }

    async fn read_single(&self, query: &dyn ReadInput) -> Result<Option<T>>;
    fn read<'a>(&'a self, query: &'a dyn ReadInput) -> Pin<Box<dyn Stream<Item = Result<T>> + Send + 'a>>;
}

#[async_trait]
pub trait ICRUDRepository<T: FromSchema = Row>: IReadonlyRepository<T> {
    async fn create(&self, item: T) -> Result<T>;
    async fn update(&self, item: T, by_where: Option<&dyn IWhere>) -> Result<Response>;
    async fn delete(&self, item: T, by_where: Option<&dyn IWhere>) -> Result<Response>;
    async fn read_single_by_id(&self, id: &dyn IdKey) -> Result<Option<T>>;

    fn id_names(&self) -> Vec<String> {
        Vec::new()
    }

    fn add_middleware(&self, _middleware: Arc<dyn CommandMiddleware>) {}
}

struct AsReadonly<T: FromSchema>(Arc<dyn ICRUDRepository<T>>);

impl<T: FromSchema> IRepository for AsReadonly<T> {
    fn entity_type(&self) -> TypeId {
        self.0.entity_type()
    }
}

#[async_trait]
impl<T: FromSchema> IReadonlyRepository<T> for AsReadonly<T> {
    async fn read_single(&self, query: &dyn ReadInput) -> Result<Option<T>> {
        self.0.read_single(query).await
    }

    fn read<'a>(&'a self, query: &'a dyn ReadInput) -> Pin<Box<dyn Stream<Item = Result<T>> + Send + 'a>> {
        self.0.read(query)
    }
}

pub fn as_readonly<T: FromSchema>(repo: Arc<dyn ICRUDRepository<T>>) -> Arc<dyn IReadonlyRepository<T>> {
    Arc::new(AsReadonly(repo))
}

pub(crate) fn map_row<T: FromSchema>(row: Row, schema: &Schema) -> Result<T> {
    T::from_schema(row, schema)
}

pub(crate) fn to_stored<T: FromSchema>(item: &T, schema: &Schema) -> Result<Row> {
    item.to_schema(schema)
}

pub(crate) fn map_stream<'a, T: FromSchema>(
    rows: Pin<Box<dyn Stream<Item = Result<Row>> + Send + 'a>>,
    schema: Schema,
) -> Pin<Box<dyn Stream<Item = Result<T>> + Send + 'a>> {
    Box::pin(rows.map(move |row| row.and_then(|row| T::from_schema(row, &schema))))
}