datafusion-odata 54.0.0

OData protocol adapter for Apache Datafusion
Documentation 
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use std::sync::Arc;

use chrono::{DateTime, Utc};
use datafusion::{
    arrow::{datatypes::SchemaRef, record_batch::RecordBatch},
    dataframe::DataFrame,
};

use crate::{
    collection::{CollectionAddr, QueryParams},
    error::{KeyColumnNotAssigned, ODataError},
};

///////////////////////////////////////////////////////////////////////////////

pub const DEFAULT_NAMESPACE: &str = "default";

///////////////////////////////////////////////////////////////////////////////

#[async_trait::async_trait]
pub trait ServiceContext: Send + Sync {
    fn service_base_url(&self) -> String;

    async fn list_collections(&self) -> Result<Vec<Arc<dyn CollectionContext>>, ODataError>;

    fn on_unsupported_feature(&self) -> OnUnsupported;
}

///////////////////////////////////////////////////////////////////////////////

#[async_trait::async_trait]
pub trait CollectionContext: Send + Sync {
    fn addr(&self) -> Result<&CollectionAddr, ODataError>;

    fn service_base_url(&self) -> Result<String, ODataError>;

    fn collection_base_url(&self) -> Result<String, ODataError>;

    fn collection_namespace(&self) -> Result<String, ODataError> {
        Ok(DEFAULT_NAMESPACE.to_string())
    }

    fn collection_name(&self) -> Result<String, ODataError>;

    // Synthetic column name that will be used to propagate entity IDs
    fn key_column_alias(&self) -> String {
        "__id__".to_string()
    }

    fn key_column(&self) -> Result<String, ODataError> {
        Err(KeyColumnNotAssigned)?
    }

    async fn last_updated_time(&self) -> DateTime<Utc>;

    async fn schema(&self) -> Result<SchemaRef, ODataError>;

    async fn query(&self, query: QueryParams) -> Result<DataFrame, ODataError>;

    fn on_unsupported_feature(&self) -> OnUnsupported;

    /// Validates the record batches that retunred from datafusion before encode them to xml
    async fn validate(&self, _record_batches: &[RecordBatch]) -> Result<(), ODataError> {
        Ok(())
    }
}

///////////////////////////////////////////////////////////////////////////////

pub enum OnUnsupported {
    /// Return an error or crash
    Error,
    /// Log error and recover as gracefully as possible
    Warn,
}