vantage_csv/

table_source.rs

use crate::operation::CsvOperation;
use async_trait::async_trait;
use indexmap::IndexMap;
use vantage_core::error;
use vantage_dataset::traits::Result;
use vantage_expressions::Expression;
use vantage_expressions::Expressive;
use vantage_expressions::traits::associated_expressions::AssociatedExpression;
use vantage_expressions::traits::datasource::DataSource;
use vantage_expressions::traits::expressive::{DeferredFn, ExpressiveEnum};
use vantage_table::column::core::{Column, ColumnType};
use vantage_table::table::Table;
use vantage_table::traits::table_source::TableSource;
use vantage_types::{Entity, Record};

use crate::Csv;
use crate::condition::apply_condition;
use crate::type_system::AnyCsvType;

impl DataSource for Csv {}

#[async_trait]
impl TableSource for Csv {
    type Column<Type>
        = Column<Type>
    where
        Type: ColumnType;
    type AnyType = AnyCsvType;
    type Value = AnyCsvType;
    type Id = String;
    type Condition = vantage_expressions::Expression<Self::Value>;
    type Source = String;

    fn eq_value_condition(&self, field: &str, value: Self::Value) -> Result<Self::Condition> {
        let column: Column<AnyCsvType> = Column::new(field);
        Ok(CsvOperation::eq(&column, value))
    }

    fn create_column<Type: ColumnType>(&self, name: &str) -> Self::Column<Type> {
        Column::new(name)
    }

    fn to_any_column<Type: ColumnType>(
        &self,
        column: Self::Column<Type>,
    ) -> Self::Column<Self::AnyType> {
        Column::from_column(column)
    }

    fn convert_any_column<Type: ColumnType>(
        &self,
        any_column: Self::Column<Self::AnyType>,
    ) -> Option<Self::Column<Type>> {
        Some(Column::from_column(any_column))
    }

    fn expr(
        &self,
        template: impl Into<String>,
        parameters: Vec<ExpressiveEnum<Self::Value>>,
    ) -> Expression<Self::Value> {
        Expression::new(template, parameters)
    }

    fn search_table_condition<E>(
        &self,
        _table: &Table<Self, E>,
        _search_value: &str,
    ) -> Expression<Self::Value>
    where
        E: Entity<Self::Value>,
    {
        // Sentinel: `apply_condition` turns it into Unsupported instead of
        // silently matching every row.
        Expression::new(crate::operation::OP_SEARCH, vec![])
    }

    async fn list_table_values<E>(
        &self,
        table: &Table<Self, E>,
    ) -> Result<IndexMap<Self::Id, Record<Self::Value>>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        let mut records = self.read_csv(table.table_name(), table.columns())?;

        for condition in table.conditions() {
            records = apply_condition(records, condition).await?;
        }

        Ok(records)
    }

    async fn get_table_value<E>(
        &self,
        table: &Table<Self, E>,
        id: &Self::Id,
    ) -> Result<Option<Record<Self::Value>>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        let records = self.read_csv(table.table_name(), table.columns())?;
        Ok(records.get(id).cloned())
    }

    async fn get_table_some_value<E>(
        &self,
        table: &Table<Self, E>,
    ) -> Result<Option<(Self::Id, Record<Self::Value>)>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        let records = self.read_csv(table.table_name(), table.columns())?;
        Ok(records.into_iter().next())
    }

    async fn get_table_count<E>(&self, table: &Table<Self, E>) -> Result<i64>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        let records = self.read_csv(table.table_name(), table.columns())?;
        Ok(records.len() as i64)
    }

    async fn get_table_sum<E>(
        &self,
        _table: &Table<Self, E>,
        _column: &Self::Column<Self::AnyType>,
    ) -> Result<Self::Value>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("Sum not implemented for CSV backend"))
    }

    async fn get_table_max<E>(
        &self,
        _table: &Table<Self, E>,
        _column: &Self::Column<Self::AnyType>,
    ) -> Result<Self::Value>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("Max not implemented for CSV backend"))
    }

    async fn get_table_min<E>(
        &self,
        _table: &Table<Self, E>,
        _column: &Self::Column<Self::AnyType>,
    ) -> Result<Self::Value>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("Min not implemented for CSV backend"))
    }

    async fn insert_table_value<E>(
        &self,
        _table: &Table<Self, E>,
        _id: &Self::Id,
        _record: &Record<Self::Value>,
    ) -> Result<Record<Self::Value>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    async fn replace_table_value<E>(
        &self,
        _table: &Table<Self, E>,
        _id: &Self::Id,
        _record: &Record<Self::Value>,
    ) -> Result<Record<Self::Value>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    async fn patch_table_value<E>(
        &self,
        _table: &Table<Self, E>,
        _id: &Self::Id,
        _partial: &Record<Self::Value>,
    ) -> Result<Record<Self::Value>>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    async fn delete_table_value<E>(&self, _table: &Table<Self, E>, _id: &Self::Id) -> Result<()>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    async fn delete_table_all_values<E>(&self, _table: &Table<Self, E>) -> Result<()>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    async fn insert_table_return_id_value<E>(
        &self,
        _table: &Table<Self, E>,
        _record: &Record<Self::Value>,
    ) -> Result<Self::Id>
    where
        E: Entity<Self::Value>,
        Self: Sized,
    {
        Err(error!("CSV is a read-only data source"))
    }

    fn related_in_condition<SourceE: Entity<Self::Value> + 'static>(
        &self,
        target_field: &str,
        source_table: &Table<Self, SourceE>,
        source_column: &str,
    ) -> Self::Condition
    where
        Self: Sized,
    {
        let src_col = self.create_column::<Self::AnyType>(source_column);
        let fk_values = self.column_table_values_expr(source_table, &src_col);
        let tgt_col = self.create_column::<Self::AnyType>(target_field);
        tgt_col.in_(fk_values.expr())
    }

    fn column_table_values_expr<'a, E, Type: ColumnType>(
        &'a self,
        table: &Table<Self, E>,
        column: &Self::Column<Type>,
    ) -> AssociatedExpression<'a, Self, Self::Value, Vec<Type>>
    where
        E: Entity<Self::Value> + 'static,
        Self: Sized,
    {
        use vantage_expressions::{
            expr_any,
            traits::{associated_expressions::AssociatedExpression, datasource::ExprDataSource},
        };

        let table_clone = table.clone();
        let col = column.name().to_string();
        let csv = self.clone();

        let inner = expr_any!("{}", {
            DeferredFn::new(move || {
                let csv = csv.clone();
                let table = table_clone.clone();
                let col = col.clone();
                Box::pin(async move {
                    let records = csv.list_table_values(&table).await?;
                    let values: Vec<AnyCsvType> = records
                        .values()
                        .filter_map(|r| r.get(&col).cloned())
                        .collect();
                    Ok(ExpressiveEnum::Scalar(AnyCsvType::new(values)))
                })
            })
        });

        let expr = expr_any!("{}", { self.defer(inner) });
        AssociatedExpression::new(expr, self)
    }
}