Expand description
§envoke
§Useful links
§Attributes
Container attributes apply to the whole struct influencing the behavior of the entire structure. Field attributes are applied to individual fields within struct, providing fine-grained control over how each field is processed. Both types of attributes allow for customizing how data is loaded, transformed, or handled.
§Naming cases
| Case | Value | Description |
|---|---|---|
| Lower case | lowercase or lower | Converts all characters to lowercase and removes binding characters |
| Upper case | UPPERCASE or UPPER | Converts all characters to uppercase and removes binding characters |
| Pascal case | PascalCase | Capitalizes the first letter of each word and removes binding |
| Camel case | camelCase | Lowercases the first letter but capitalizes the first letter of subsequent words while removing binding characters |
| Snake case | snake_case | Converts names to lowercase and uses underscores _ to separate words |
| Screaming snake case | SCREAMING_SNAKE_CASE | Converts names to uppercase and uses underscores _ to separate words |
| Kebab case | kebab-case | Converts names to lowercase and uses hyphens - to separate words |
| Screaming kebab case | SCREAMING-KEBAB-CASE | Converts names to uppercase and uses hyphens - to separate words |
§Structs
Container
Below are the current implemented container attributes. This list will be updated as more are added or changed.
| Attribute | Default | Description |
|---|---|---|
prefix | None | Set a custom prefix which will be prepended infront of environment variables before fetching |
suffix | None | Set a custom prefix which will be appended infront of environment variables before fetching |
delimiter | None | Set a customer delimiter used for separated prefix, environment variable, and suffix. NB! If you are using the rename_all attribute as well it will take priority over the delimiter. It can still be useful to include the delimiter to ensure the prefix, environment variable, and suffix are separated before renaming occurs otherwise they will be interpreted as a single word! |
rename_all | None | Rename all environment variables to a different naming case. See name cases for a full list and description of the different options. |
dotenv | None | Set a dotenv file to use when loading environment variables into structs/enums. Note that environment variables in the process’s environment have a higher priority than those found in the dotenv file. |
Field
Below are the current implemented field attributes. This list will be updated as more are added or changed.
| Attribute | Default | Description |
|---|---|---|
env | field name | Environment variable name to load the field value from. Can be chained multiple times to allow for fallbacks. The macro follows a first come, first serve basis meaning it attempts to load the variables in the order they are listed. Once an value is found it will try to parse it into the specified type. If it fails it will return an error and wont try the remaining ones in the list. This behavior might change in the future. Optionally, you can supply your own parsing function. See parse_fn for more information! |
default | None | Use the default value if the environment variable is not found. Optionally to statically assign a value to the field env can be omitted. |
parse_fn | None | Set a custom parsing function for parsing the retrieved value before assigning it to the field. This can be useful when the fields type does not implement the FromStr trait. Requires arg_type to be set. Cannot be used together with try_parse_fn. |
try_parse_fn | None | Similar to parse_fn except it can fail. Useful if the parse function cannot always succeed, e.g., parsing a string to an UUID. Requires arg_type to be set. Cannot be used together with parse_fn. |
arg_type | None | Specify the argument type which the parse_fn function requires. As I don’t know if it is possible to find the type automatically this argument is required such that the environment variable value can be parsed into the expected type first before being set as the argument in the function call. |
validate_fn | None | Set a custom validation function for ensuring the loaded value meets expectations. Note validate_fn supports both direct assignment and parentheses assignments. See example |
delimiter | Comma (,) | Used when parsing environment variable which is a stringified map or set. The delimiter specifies the boundary between values. |
no_prefix | False | Disable adding the global prefix to this environment variable. This will also remove the delimiter that wouldn’t normally be between the environment variable and prefix |
no_suffix | False | Disable adding the global suffix to this environment variable. This will also remove the delimiter that wouldn’t normally be between the environment variable and suffix |
nested | False | Indicate that the field is a struct. Required when the field type is another struct |
ignore | False | Indicate that the derive macro should ignore this field when parsing. Note that this only works on optional fields. |
§Enums
Container
Below are the current implemented container attributes. This list will be updated as more are added or changed.
| Attribute | Default | Description |
|---|---|---|
env | container name | Environment variable name to load the field value from. Can be chained multiple times to allow for fallbacks. The macro follows a first come, first serve basis meaning it attempts to load the variables in the order they are listed. Once an value is found it will try to parse it into the specified type. If it fails it will return an error and wont try the remaining ones in the list. This behavior might change in the future. |
prefix | None | Set a custom prefix which will be prepended infront of environment variables before fetching |
suffix | None | Set a custom prefix which will be appended infront of environment variables before fetching |
delimiter | None | Set a customer delimiter used for separated prefix, environment variable, and suffix. NB! If you are using the rename_all attribute as well it will take priority over the delimiter. It can still be useful to include the delimiter to ensure the prefix, environment variable, and suffix are separated before renaming occurs otherwise they will be interpreted as a single word! |
rename_all | None | Rename all environment variables to a different naming case. See name cases for a full list and description of the different options. |
dotenv | None | Set a dotenv file to use when loading environment variables into structs/enums. Note that environment variables in the process’s environment have a higher priority than those found in the dotenv file. |
Variant
Below are the current implemented variant attributes. This list will be updated as more are added or changed.
| Attribute | Default | Description |
|---|---|---|
rename | None | Rename the name of the field. This overwrites the default field name and as such this name will be used instead. If you want extra names to match on in addition to the field name use alias instead. |
alias | None | Additional names, including the field name, to match on. |
no_prefix | False | Disable adding the global prefix to this environment variable. This will also remove the delimiter that wouldn’t normally be between the environment variable and prefix |
no_suffix | False | Disable adding the global suffix to this environment variable. This will also remove the delimiter that wouldn’t normally be between the environment variable and suffix |
default | False | Set this as the default variant to load if none of the names matches the container value |
§License
Licensed under either of Apache License, Version 2.0 or MIT license at your option.Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.