README
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Default values
typedcfg applies defaults before decoding sources; decoded explicit zero values are preserved. The standalone helper defaults.SetDefaults(&cfg) fills zero fields on an existing struct.
type Config struct {
Port int `json:"port" default:"8080"`
Timeout time.Duration `json:"timeout" default:"30s"`
Tags []string `json:"tags" default:"web,api"`
Database struct {
Host string `json:"host" default:"localhost"`
} `json:"database"`
}
Supported tags: strings, signed/unsigned integers, floats, booleans, time.Duration, comma-separated string slices, and pointers to these types. Nested value structs are traversed automatically. Unsupported field kinds do not receive a default. This helper parses tags but does not validate application constraints or detect narrowing overflow when assigning numeric values to smaller field types.
A nil pointer needs its own default tag to be allocated; for a struct pointer use default:"" so nested defaults are visited. Non-nil pointers are preserved by this helper. Defaults are not recursively applied to collection elements or objects allocated later by the decoder. For straightforward predictable defaults, prefer nested value structs.
cfg := Config{}
if err := defaults.SetDefaults(&cfg); err != nil {
return err
}
Documentation
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Overview ¶
Package defaults applies default tags to zero-valued struct fields.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func SetDefaults ¶
SetDefaults fills zero-valued fields from their default tags and recurses into nested value structs. Nil pointers require their own default tag to be allocated; existing non-nil pointers and collection elements are not traversed.
Supported tag format: `default:"value"`
Examples:
type Config struct {
Port int `default:"8080"`
Host string `default:"localhost"`
Timeout time.Duration `default:"30s"`
Debug bool `default:"false"`
Tags []string `default:"tag1,tag2,tag3"`
}
Inputs other than a pointer to a struct are ignored. Tag parsing errors are returned; application constraints and narrowing numeric overflow are not checked.
Types ¶
This section is empty.
Source Files