Enum aws_sdk_dynamodb::types::ProjectionType

#[non_exhaustive]
pub enum ProjectionType {
    All,
    Include,
    KeysOnly,
    Unknown(UnknownVariantValue),
}

When writing a match expression against ProjectionType, it is important to ensure your code is forward-compatible. That is, if a match arm handles a case for a feature that is supported by the service but has not been represented as an enum variant in a current version of SDK, your code should continue to work when you upgrade SDK to a future version in which the enum does include a variant for that feature.

Here is an example of how you can make a match expression forward-compatible:

# let projectiontype = unimplemented!();
match projectiontype {
    ProjectionType::All => { /* ... */ },
    ProjectionType::Include => { /* ... */ },
    ProjectionType::KeysOnly => { /* ... */ },
    other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
    _ => { /* ... */ },
}

The above code demonstrates that when projectiontype represents NewFeature, the execution path will lead to the second last match arm, even though the enum does not contain a variant ProjectionType::NewFeature in the current version of SDK. The reason is that the variable other, created by the @ operator, is bound to ProjectionType::Unknown(UnknownVariantValue("NewFeature".to_owned())) and calling as_str on it yields "NewFeature". This match expression is forward-compatible when executed with a newer version of SDK where the variant ProjectionType::NewFeature is defined. Specifically, when projectiontype represents NewFeature, the execution path will hit the second last match arm as before by virtue of calling as_str on ProjectionType::NewFeature also yielding "NewFeature".

Explicitly matching on the Unknown variant should be avoided for two reasons:

• The inner data UnknownVariantValue is opaque, and no further information can be extracted.
• It might inadvertently shadow other intended match arms.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

All

Include

KeysOnly

Unknown(UnknownVariantValue)

👎Deprecated: Don’t directly match on Unknown. See the docs on this enum for the correct way to handle unknown variants.

Unknown contains new variants that have been added since this code was generated.

Implementations

impl ProjectionType

pub fn as_str(&self) -> &str

Returns the &str value of the enum member.

pub const fn values() -> &'static [&'static str]

Returns all the &str representations of the enum members.

impl ProjectionType

pub fn try_parse(value: &str) -> Result<Self, UnknownVariantError>

Parses the enum value while disallowing unknown variants.

Unknown variants will result in an error.

Trait Implementations

impl AsRef<str> for ProjectionType

fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for ProjectionType

fn clone(&self) -> ProjectionType

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ProjectionType

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

Formats the value using the given formatter.

impl Display for ProjectionType

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

Formats the value using the given formatter.

impl From<&str> for ProjectionType

fn from(s: &str) -> Self

Converts to this type from the input type.

impl FromStr for ProjectionType

type Err = Infallible

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, <Self as FromStr>::Err>

Parses a string s to return a value of this type.

impl Hash for ProjectionType

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for ProjectionType

fn cmp(&self, other: &ProjectionType) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for ProjectionType

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for ProjectionType

fn partial_cmp(&self, other: &ProjectionType) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for ProjectionType

impl StructuralPartialEq for ProjectionType