Enum BuildError 

pub enum BuildError {
    SettingsMissing,
    DefaultPoolMissing,
    BackendDetect(BackendDetectError),
    SystemCheckFailed {
        findings: Vec<SystemCheckFinding>,
    },
    DependencyNotFound {
        plugin: &'static str,
        missing: &'static str,
    },
    PluginCycle {
        names: Vec<&'static str>,
    },
    DuplicatePluginName {
        name: &'static str,
    },
    ReservedPluginName,
    PluginOnReady {
        plugin: &'static str,
        source: Box<dyn Error + Send + Sync>,
    },
    TemplatesInit(TemplateError),
    PluginDatabaseAlias {
        plugin: &'static str,
        alias: &'static str,
    },
    DatabaseBackendMismatch {
        url_backend: &'static str,
        pool_backend: &'static str,
    },
    CrossDatabaseForeignKey {
        model: &'static str,
        field: &'static str,
        model_db: &'static str,
        target_db: &'static str,
    },
    DuplicateStaticNamespace {
        namespace: &'static str,
        first_plugin: &'static str,
        second_plugin: &'static str,
    },
}

Errors that can occur during AppBuilder::build().

Variants

SettingsMissing

.settings(Settings) wasn’t called on the builder.

DefaultPoolMissing

.database("default", pool) wasn’t called on the builder.

BackendDetect(BackendDetectError)

The URL scheme in settings.database_url doesn’t match any shipped backend.

SystemCheckFailed

One or more system checks failed with Severity::Error. The full list of findings is in the variant.

Fields

findings: Vec<SystemCheckFinding>

DependencyNotFound

A plugin’s dependencies() lists a plugin that was never registered with .plugin(...). Carries the unmet name plus the plugin that asked for it.

Fields

plugin: &'static str

missing: &'static str

PluginCycle

The dependency graph has a cycle. Carries the plugin names that form it (in any cyclic order; the diagnostic is “these N plugins reference each other”).

Fields

names: Vec<&'static str>

DuplicatePluginName

Two registered plugins share a name(). Plugin names are keys in the migration tracking table and the dependency graph; a collision would break both.

Fields

name: &'static str

ReservedPluginName

A plugin claimed the reserved "app" name (used by the implicit plugin that owns .model::<T>() registrations).

PluginOnReady

A plugin’s on_ready returned an error. Carries the plugin’s name plus the underlying error.

Fields

plugin: &'static str

source: Box<dyn Error + Send + Sync>

TemplatesInit(TemplateError)

The templates engine failed to initialise. Carries the underlying TemplateError (an IO error reading a template file, or a syntax error in one of the loaded templates).

PluginDatabaseAlias

A plugin’s database() returned an alias that isn’t in the registered pool set. Surfaces a typo at boot with a clear “register the pool first” diagnostic instead of letting db::pool_for panic at first query.

Fields

plugin: &'static str

alias: &'static str

DatabaseBackendMismatch

The URL-derived backend (from settings.database_url) doesn’t match the runtime type of the default pool passed to .database("default", ...). Catches the case where the URL says postgres:// but a SqlitePool was registered, or vice versa.

Fields

url_backend: &'static str

pool_backend: &'static str

CrossDatabaseForeignKey

A foreign key targets a model on a different database than the model that declares it, and the field has NOT opted out of the physical constraint. A REFERENCES clause can’t span databases, so this would emit invalid DDL. Fix by either routing both models to the same database, or marking the FK #[umbral(db_constraint = false)] to keep it a logical-only relation. Closes gaps2 #22.

Fields

model: &'static str

field: &'static str

model_db: &'static str

target_db: &'static str

DuplicateStaticNamespace

Two plugins declared the same static namespace via Plugin::static_dirs(). Namespaces are the per-plugin URL/disk segment under static_url / static_root; a collision would silently shadow one plugin’s assets with another’s, so the build fails loudly and names both plugins.

Fields

namespace: &'static str

first_plugin: &'static str

second_plugin: &'static str

Trait Implementations

impl Debug for BuildError

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

Formats the value using the given formatter.

impl Display for BuildError

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

Formats the value using the given formatter.

impl Error for BuildError

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.