Struct figment::Metadata [−][src]
pub struct Metadata { pub name: Cow<'static, str>, pub source: Option<Source>, pub provide_location: Option<&'static Location<'static>>, // some fields omitted }
Expand description
Metadata about a configuration value: its source’s name and location.
Overview
Every Value
produced by a Figment
is Tag
ed with Metadata
by its producing Provider
. The metadata consists of:
- A name for the source, e.g. “TOML File”.
- The
Source
itself, if it is known. - A default or custom interpolater.
- A source
Location
where a value’s provider was added to the containing figment, if it is known.
This information is used to produce insightful error messages as well as to
generate values like RelativePathBuf
that know about their configuration
source.
Errors
Error
s produced by Figment
s contain the Metadata
for the value
that caused the error. The Display
implementation for Error
uses the
metadata’s interpolater to display the path to the key for the value that
caused the error.
Interpolation
Interpolation takes a figment profile and key path (a.b.c
) and turns it
into a source-native path. The default interpolater returns a figment key
path prefixed with the profile if the profile is custom:
${profile}.${a}.${b}.${c}
Providers are free to implement any interpolater for their metadata. For
example, the interpolater for Env
uppercases each path key:
use figment::Metadata; let metadata = Metadata::named("environment variable(s)") .interpolater(|profile, path| { let keys: Vec<_> = path.iter() .map(|k| k.to_ascii_uppercase()) .collect(); format!("{}", keys.join(".")) }); let profile = figment::Profile::Default; let interpolated = metadata.interpolate(&profile, &["key", "path"]); assert_eq!(interpolated, "KEY.PATH");
Fields
name: Cow<'static, str>
The name of the configuration source for a given value.
source: Option<Source>
The source of the configuration value, if it is known.
provide_location: Option<&'static Location<'static>>
The source location where this value’s provider was added to the containing figment, if it is known.
Implementations
Creates a new Metadata
with the given name
and source
.
Example
use figment::Metadata; let metadata = Metadata::from("AWS Config Store", "path/to/value"); assert_eq!(metadata.name, "AWS Config Store"); assert_eq!(metadata.source.unwrap().custom(), Some("path/to/value"));
Creates a new Metadata
with the given name
and no source.
Example
use figment::Metadata; let metadata = Metadata::named("AWS Config Store"); assert_eq!(metadata.name, "AWS Config Store"); assert!(metadata.source.is_none());
Sets the source
of self
to Some(source)
.
Example
use figment::Metadata; let metadata = Metadata::named("AWS Config Store").source("config/path"); assert_eq!(metadata.name, "AWS Config Store"); assert_eq!(metadata.source.unwrap().custom(), Some("config/path"));
Sets the interpolater
of self
to the function f
. The interpolater
can be invoked via Metadata::interpolate()
.
Example
use figment::Metadata; let metadata = Metadata::named("environment variable(s)") .interpolater(|profile, path| { let keys: Vec<_> = path.iter() .map(|k| k.to_ascii_uppercase()) .collect(); format!("{}", keys.join(".")) }); let profile = figment::Profile::Default; let interpolated = metadata.interpolate(&profile, &["key", "path"]); assert_eq!(interpolated, "KEY.PATH");
Runs the interpolater in self
on profile
and keys
.
Example
use figment::{Metadata, Profile}; let url = "ftp://config.dev"; let md = Metadata::named("Network").source(url) .interpolater(move |profile, keys| match profile.is_custom() { true => format!("{}/{}/{}", url, profile, keys.join("/")), false => format!("{}/{}", url, keys.join("/")), }); let interpolated = md.interpolate(&Profile::Default, &["key", "path"]); assert_eq!(interpolated, "ftp://config.dev/key/path"); let profile = Profile::new("static"); let interpolated = md.interpolate(&profile, &["key", "path"]); assert_eq!(interpolated, "ftp://config.dev/static/key/path");
Trait Implementations
Auto Trait Implementations
impl !RefUnwindSafe for Metadata
impl !UnwindSafe for Metadata
Blanket Implementations
Mutably borrows from an owned value. Read more
pub fn vzip(self) -> V