src/list.rs

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//   http://www.apache.org/licenses/LICENSE-2.0
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//! Paginated Listing

use super::Result;
use crate::ListResult;
use async_trait::async_trait;
use std::borrow::Cow;

/// Options for a paginated list request
#[derive(Debug, Default, Clone)]
pub struct PaginatedListOptions {
    /// Path to start listing from
    ///
    /// Note: Not all stores support this
    ///
    /// For stores that do support this, the returned
    /// result should not include the object with this key.
    pub offset: Option<String>,

    /// A delimiter use to group keys with a common prefix
    ///
    /// Note: Some stores only support `/`
    pub delimiter: Option<Cow<'static, str>>,

    /// The maximum number of paths to return
    pub max_keys: Option<usize>,

    /// A page token from a previous request
    ///
    /// Note: Behaviour is implementation defined if the previous request
    /// used a different prefix or options
    pub page_token: Option<String>,

    /// Implementation-specific extensions. Intended for use by implementations
    /// that need to pass context-specific information (like tracing spans) via trait methods.
    ///
    /// These extensions are ignored entirely by backends offered through this crate.
    pub extensions: http::Extensions,
}

/// A [`ListResult`] with optional pagination token
#[derive(Debug)]
pub struct PaginatedListResult {
    /// The list result
    pub result: ListResult,
    /// If result set truncated, the pagination token to fetch next results
    pub page_token: Option<String>,
}

/// A low-level interface for interacting with paginated listing APIs
///
/// Most use-cases should prefer [`ObjectStore::list`] as this is supported by more
/// backends, including [`LocalFileSystem`], however, [`PaginatedListStore`] can be
/// used where stateless pagination or non-path segment based listing is required
///
/// [`ObjectStore::list`]: crate::ObjectStore::list
/// [`LocalFileSystem`]: crate::local::LocalFileSystem
#[async_trait]
pub trait PaginatedListStore: Send + Sync + 'static {
    /// Perform a paginated list request
    ///
    /// Note: the order of returned objects is not guaranteed and
    /// unlike [`ObjectStore::list`] a trailing delimiter is not
    /// automatically added to `prefix`
    ///
    /// [`ObjectStore::list`]: crate::ObjectStore::list
    async fn list_paginated(
        &self,
        prefix: Option<&str>,
        opts: PaginatedListOptions,
    ) -> Result<PaginatedListResult>;
}