README
¶
cast
Easy and safe casting from one type to another in Go
Don’t Panic! ... Cast
What is Cast?
Cast is a library to convert between different go types in a consistent and easy way.
Cast provides simple functions to easily convert a number to a string, an interface into a bool, etc. Cast does this intelligently when an obvious conversion is possible. It doesn’t make any attempts to guess what you meant, for example you can only convert a string to an int when it is a string representation of an int such as “8”. Cast was developed for use in Hugo, a website engine which uses YAML, TOML or JSON for meta data.
Why use Cast?
When working with dynamic data in Go you often need to cast or convert the data from one type into another. Cast goes beyond just using type assertion (though it uses that when possible) to provide a very straightforward and convenient library.
If you are working with interfaces to handle things like dynamic content you’ll need an easy way to convert an interface into a given type. This is the library for you.
If you are taking in data from YAML, TOML or JSON or other formats which lack full types, then Cast is the library for you.
Usage
Cast provides a handful of To_____ methods. These methods will always return the desired type. If input is provided that will not convert to that type, the 0 or nil value for that type will be returned.
Cast also provides identical methods To_____E. These return the same result as the To_____ methods, plus an additional error which tells you if it successfully converted. Using these methods you can tell the difference between when the input matched the zero value or when the conversion failed and the zero value was returned.
The following examples are merely a sample of what is available. Please review the code for a complete set.
Example ‘ToString’:
cast.ToString("mayonegg") // "mayonegg"
cast.ToString(8) // "8"
cast.ToString(8.31) // "8.31"
cast.ToString([]byte("one time")) // "one time"
cast.ToString(nil) // ""
var foo interface{} = "one more time"
cast.ToString(foo) // "one more time"
Example ‘ToInt’:
cast.ToInt(8) // 8
cast.ToInt(8.31) // 8
cast.ToInt("8") // 8
cast.ToInt(true) // 1
cast.ToInt(false) // 0
var eight interface{} = 8
cast.ToInt(eight) // 8
cast.ToInt(nil) // 0
License
The project is licensed under the MIT License.
Documentation
¶
Overview ¶
Copyright © 2014 Steve Francia <spf@spf13.com>.
Use of this source code is governed by an MIT-style license that can be found in the LICENSE file.
Package cast provides easy and safe casting in Go.
Example ¶
package main
import (
"fmt"
"github.com/spf13/cast"
)
func main() {
// Cast a value to another type
{
v, err := cast.ToIntE("1234")
if err != nil {
panic(err)
}
fmt.Printf("%T(%v)\n", v, v)
}
// Alternatively, you can use the generic [ToE] function for [Basic] types
{
v, err := cast.ToE[int]("4321")
if err != nil {
panic(err)
}
fmt.Printf("%T(%v)\n", v, v)
}
// You can suppress errors by using the non-error versions
{
v := cast.ToInt("9876")
fmt.Printf("%T(%v)\n", v, v)
}
// Similarly, there is a generic [To] function for [Basic] types
{
v := cast.To[int]("6789")
fmt.Printf("%T(%v)\n", v, v)
}
// Finally, you can use [Must] to panic if there is an error.
{
v := cast.Must[int](cast.ToE[int]("5555"))
fmt.Printf("%T(%v)\n", v, v)
}
}
Output: int(1234) int(4321) int(9876) int(6789) int(5555)
Index ¶
- func Must[T any](i any, err error) T
- func StringToDate(s string) (time.Time, error)
- func StringToDateInDefaultLocation(s string, location *time.Location) (time.Time, error)
- func To[T Basic](i any) T
- func ToBool(i any) bool
- func ToBoolE(i any) (bool, error)
- func ToBoolSlice(i any) []bool
- func ToBoolSliceE(i any) ([]bool, error)
- func ToDuration(i any) time.Duration
- func ToDurationE(i any) (time.Duration, error)
- func ToDurationSlice(i any) []time.Duration
- func ToDurationSliceE(i any) ([]time.Duration, error)
- func ToE[T Basic](i any) (T, error)
- func ToFloat32(i any) float32
- func ToFloat32E(i any) (float32, error)
- func ToFloat32SliceE(i any) ([]float32, error)
- func ToFloat64(i any) float64
- func ToFloat64E(i any) (float64, error)
- func ToFloat64Slice(i any) []float64
- func ToFloat64SliceE(i any) ([]float64, error)
- func ToInt(i any) int
- func ToInt16(i any) int16
- func ToInt16E(i any) (int16, error)
- func ToInt16SliceE(i any) ([]int16, error)
- func ToInt32(i any) int32
- func ToInt32E(i any) (int32, error)
- func ToInt32SliceE(i any) ([]int32, error)
- func ToInt64(i any) int64
- func ToInt64E(i any) (int64, error)
- func ToInt64Slice(i any) []int64
- func ToInt64SliceE(i any) ([]int64, error)
- func ToInt8(i any) int8
- func ToInt8E(i any) (int8, error)
- func ToInt8SliceE(i any) ([]int8, error)
- func ToIntE(i any) (int, error)
- func ToIntSlice(i any) []int
- func ToIntSliceE(i any) ([]int, error)
- func ToNumber[T Number](i any) T
- func ToNumberE[T Number](i any) (T, error)
- func ToSlice(i any) []any
- func ToSliceE(i any) ([]any, error)
- func ToString(i any) string
- func ToStringE(i any) (string, error)
- func ToStringMap(i any) map[string]any
- func ToStringMapBool(i any) map[string]bool
- func ToStringMapBoolE(i any) (map[string]bool, error)
- func ToStringMapE(i any) (map[string]any, error)
- func ToStringMapInt(i any) map[string]int
- func ToStringMapInt64(i any) map[string]int64
- func ToStringMapInt64E(i any) (map[string]int64, error)
- func ToStringMapIntE(i any) (map[string]int, error)
- func ToStringMapString(i any) map[string]string
- func ToStringMapStringE(i any) (map[string]string, error)
- func ToStringMapStringSlice(i any) map[string][]string
- func ToStringMapStringSliceE(i any) (map[string][]string, error)
- func ToStringSlice(i any) []string
- func ToStringSliceE(i any) ([]string, error)
- func ToTime(i any) time.Time
- func ToTimeE(i any) (time.Time, error)
- func ToTimeInDefaultLocation(i any, location *time.Location) time.Time
- func ToTimeInDefaultLocationE(i any, location *time.Location) (tim time.Time, err error)
- func ToUint(i any) uint
- func ToUint16(i any) uint16
- func ToUint16E(i any) (uint16, error)
- func ToUint16SliceE(i any) ([]uint16, error)
- func ToUint32(i any) uint32
- func ToUint32E(i any) (uint32, error)
- func ToUint32SliceE(i any) ([]uint32, error)
- func ToUint64(i any) uint64
- func ToUint64E(i any) (uint64, error)
- func ToUint64SliceE(i any) ([]uint64, error)
- func ToUint8(i any) uint8
- func ToUint8E(i any) (uint8, error)
- func ToUint8SliceE(i any) ([]uint8, error)
- func ToUintE(i any) (uint, error)
- func ToUintSlice(i any) []uint
- func ToUintSliceE(i any) ([]uint, error)
- type Basic
- type Number
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Must ¶ added in v1.9.0
Must is a helper that wraps a call to a cast function and panics if the error is non-nil.
func StringToDate ¶
StringToDate attempts to parse a string into a time.Time type using a predefined list of formats.
If no suitable format is found, an error is returned.
func StringToDateInDefaultLocation ¶ added in v1.4.0
StringToDateInDefaultLocation casts an empty interface to a time.Time, interpreting inputs without a timezone to be in the given location, or the local timezone if nil.
func ToBoolSliceE ¶
ToBoolSliceE casts any value to a(n) []bool type.
func ToDuration ¶
ToDuration casts any value to a(n) time.Duration type.
func ToDurationE ¶
ToDurationE casts any value to a time.Duration type.
func ToDurationSlice ¶ added in v1.1.0
ToDurationSlice casts any value to a(n) []time.Duration type.
func ToDurationSliceE ¶ added in v1.1.0
ToDurationSliceE casts any value to a(n) []time.Duration type.
func ToFloat32E ¶
ToFloat32E casts an interface to a float32 type.
func ToFloat32SliceE ¶ added in v1.9.0
ToFloat32SliceE casts any value to a(n) []float32 type.
func ToFloat64E ¶
ToFloat64E casts an interface to a float64 type.
func ToFloat64Slice ¶ added in v1.8.0
ToFloat64Slice casts any value to a(n) []float64 type.
func ToFloat64SliceE ¶ added in v1.8.0
ToFloat64SliceE casts any value to a(n) []float64 type.
func ToInt16SliceE ¶ added in v1.9.0
ToInt16SliceE casts any value to a(n) []int16 type.
func ToInt32SliceE ¶ added in v1.9.0
ToInt32SliceE casts any value to a(n) []int32 type.
func ToInt64Slice ¶ added in v1.8.0
ToInt64Slice casts any value to a(n) []int64 type.
func ToInt64SliceE ¶ added in v1.8.0
ToInt64SliceE casts any value to a(n) []int64 type.
func ToInt8SliceE ¶ added in v1.9.0
ToInt8SliceE casts any value to a(n) []int8 type.
func ToIntSliceE ¶
ToIntSliceE casts any value to a(n) []int type.
func ToStringMap ¶
ToStringMap casts any value to a(n) map[string]any type.
func ToStringMapBool ¶
ToStringMapBool casts any value to a(n) map[string]bool type.
func ToStringMapBoolE ¶
ToStringMapBoolE casts any value to a map[string]bool type.
func ToStringMapE ¶
ToStringMapE casts any value to a map[string]any type.
func ToStringMapInt ¶ added in v1.3.0
ToStringMapInt casts any value to a(n) map[string]int type.
func ToStringMapInt64 ¶ added in v1.3.0
ToStringMapInt64 casts any value to a(n) map[string]int64 type.
func ToStringMapInt64E ¶ added in v1.3.0
ToStringMapInt64E casts any value to a map[string]int64 type.
func ToStringMapIntE ¶ added in v1.3.0
ToStringMapIntE casts any value to a map[string]int type.
func ToStringMapString ¶
ToStringMapString casts any value to a(n) map[string]string type.
func ToStringMapStringE ¶
ToStringMapStringE casts any value to a map[string]string type.
func ToStringMapStringSlice ¶
ToStringMapStringSlice casts any value to a(n) map[string][]string type.
func ToStringMapStringSliceE ¶
ToStringMapStringSliceE casts any value to a map[string][]string type.
func ToStringSlice ¶
ToStringSlice casts any value to a(n) []string type.
func ToStringSliceE ¶
ToStringSliceE casts any value to a []string type.
func ToTimeInDefaultLocation ¶ added in v1.4.0
ToTimeInDefaultLocation casts any value to a(n) time.Time type.
func ToTimeInDefaultLocationE ¶ added in v1.4.0
ToTimeInDefaultLocationE casts an empty interface to time.Time, interpreting inputs without a timezone to be in the given location, or the local timezone if nil.
func ToUint16SliceE ¶ added in v1.9.0
ToUint16SliceE casts any value to a(n) []uint16 type.
func ToUint32SliceE ¶ added in v1.9.0
ToUint32SliceE casts any value to a(n) []uint32 type.
func ToUint64SliceE ¶ added in v1.9.0
ToUint64SliceE casts any value to a(n) []uint64 type.
func ToUint8SliceE ¶ added in v1.9.0
ToUint8SliceE casts any value to a(n) []uint8 type.
func ToUintSlice ¶ added in v1.8.0
ToUintSlice casts any value to a(n) []uint type.
func ToUintSliceE ¶ added in v1.8.0
ToUintSliceE casts any value to a(n) []uint type.
Source Files
Directories