Struct SchemaAhead 

pub struct SchemaAhead { /* private fields */ }

A store written by a build newer than this one: it records migrations this binary has never heard of. Produced by Store::schema_ahead.

Why this is its own type, and not a StoreError variant

Opening such a store is not an error and reading it is provably sound — migrations are additive in effect, so every column an older build selects is still there (the one DROP TABLE in [crate::migrations] is a table rebuild that re-selects every prior column). What is not sound is rewriting the graph: this build would re-extract every file with its older extractor and replace the newer build’s content with worse content, silently. So the refusal belongs on the write paths, and the carrier of that refusal has no business in the type every Store call returns.

The second reason is semver, and it is the binding one. StoreError is a public enum on a published 1.x crate and is not #[non_exhaustive], so adding a variant would stop a downstream exhaustive match from compiling — a breaking change, which in this workspace means a major bump of all seven crates. A new type is purely additive. Its fields are private and read through accessors for the same reason: adding one later stays non-breaking.

Implementations

impl SchemaAhead

pub fn store_version(&self) -> u32

The highest schema version this store records — necessarily one this build does not know.

pub fn build_version(&self) -> u32

The highest schema version this build knows how to apply.

pub fn unknown_versions(&self) -> &[u32]

Every recorded version this build has never heard of, ascending. Never empty. More than one means the store ran several unknown migrations, not that anything is inconsistent.

Trait Implementations

impl Clone for SchemaAhead

fn clone(&self) -> SchemaAhead

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SchemaAhead

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for SchemaAhead

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for SchemaAhead

impl Error for SchemaAhead

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for SchemaAhead

fn eq(&self, other: &SchemaAhead) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for SchemaAhead