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Writing the README. Handling a few more cases, adding more tests.
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README.md
70
README.md
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@ -1,4 +1,72 @@
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cast
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====
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easy casting from one type to another in Go
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Easy and safe casting from one type to another in Go
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Don’t Panic! ... Cast
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## What is Cast?
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Cast is a library to convert between different go types in a consistent and easy way.
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Cast provides simple functions to easily convert a number to a string, an
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interface into a bool, etc. Cast does this intelligently when an obvious
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conversion is possible. It doesn’t make any attempts to guess what you meant,
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for example you can only convert a string to an int when it is a string
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representation of an int such as “8”. Cast was developed for use in
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[Hugo](http://hugo.spf13.com), a website engine which uses YAML, TOML or JSON
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for meta data.
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## Why use Cast?
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When working with dynamic data in Go you often need to cast or convert the data
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from one type into another. Cast goes beyond just using type assertion (though
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it uses that when possible) to provide a very straightforward and convenient
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library.
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If you are working with interfaces to handle things like dynamic content
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you’ll need an easy way to convert an interface into a given type. This
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is the library for you.
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If you are taking in data from YAML, TOML or JSON or other formats which lack
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full types, then Cast is the library for you.
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## Usage
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Cast provides a handful of To_____ methods. These methods will always return
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the desired type. **If input is provided that will not convert to that type, the
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0 or nil value for that type will be returned**.
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Cast also provides identical methods To_____E. These return the same result as
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the To_____ methods, plus an additional bool which tells you if it successfully
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converted. Using these methods you can tell the difference between when the
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input matched the zero value or when the conversion failed and the zero value
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was returned.
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The following examples are merely a sample of what is available. Please review
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the code for a complete set.
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### Example ‘ToString’:
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cast.ToString("mayonegg") // "mayonegg"
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cast.ToString(8) // "8"
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cast.ToString(8.31) // "8.31"
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cast.ToString([]byte("one time")) // "one time"
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cast.ToString(nil) // ""
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var foo interface{} = "one more time"
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cast.ToString(foo) // "one more time"
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### Example ‘ToInt’:
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cast.ToInt(8) // 8
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cast.ToInt(8.31) // 8
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cast.ToInt("8") // 8
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cast.ToInt(true) // 1
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cast.ToInt(false) // 0
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var eight interface{} = 8
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cast.ToInt(eight) // 8
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cast.ToInt(nil) // 0
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10
cast_test.go
10
cast_test.go
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@ -14,12 +14,22 @@ import (
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func TestToInt(t *testing.T) {
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var eight interface{} = 8
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assert.Equal(t, ToInt(8), 8)
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assert.Equal(t, ToInt(8.31), 8)
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assert.Equal(t, ToInt("8"), 8)
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assert.Equal(t, ToInt(true), 1)
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assert.Equal(t, ToInt(false), 0)
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assert.Equal(t, ToInt(eight), 8)
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}
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func TestToString(t *testing.T) {
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var foo interface{} = "one more time"
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assert.Equal(t, ToString(8), "8")
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assert.Equal(t, ToString(8.12), "8.12")
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assert.Equal(t, ToString([]byte("one time")), "one time")
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assert.Equal(t, ToString(foo), "one more time")
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assert.Equal(t, ToString(nil), "")
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}
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func TestMaps(t *testing.T) {
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var taxonomies = map[interface{}]interface{}{"tag": "tags", "group": "groups"}
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assert.Equal(t, ToStringMap(taxonomies), map[string]interface{}{"tag": "tags", "group": "groups"})
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151
caste.go
151
caste.go
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@ -53,6 +53,84 @@ func ToBoolE(i interface{}) (bool, bool) {
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return false, false
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}
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func ToFloat64E(i interface{}) (float64, bool) {
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switch s := i.(type) {
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case float64:
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return s, true
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case float32:
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return float64(s), true
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case string:
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v, err := strconv.ParseFloat(s, 64)
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if err == nil {
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return float64(v), true
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} else {
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jww.ERROR.Printf("Unable to Cast %#v to float", i)
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jww.ERROR.Println(err)
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}
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default:
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jww.ERROR.Printf("Unable to Cast %#v to float", i)
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}
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return 0.0, false
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}
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func ToIntE(i interface{}) (int, bool) {
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switch s := i.(type) {
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case int:
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return s, true
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case int64:
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return int(s), true
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case int32:
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return int(s), true
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case int16:
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return int(s), true
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case int8:
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return int(s), true
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case string:
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v, err := strconv.ParseInt(s, 0, 0)
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if err == nil {
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return int(v), true
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} else {
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jww.ERROR.Printf("Unable to Cast %#v to int", i)
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jww.ERROR.Println(err)
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}
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case float64:
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return int(s), true
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case bool:
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if bool(s) {
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return 1, true
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} else {
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return 0, true
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}
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case nil:
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return 0, true
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default:
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jww.ERROR.Printf("Unable to Cast %#v to int", i)
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}
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return 0, false
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}
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func ToStringE(i interface{}) (string, bool) {
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switch s := i.(type) {
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case string:
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return s, true
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case float64:
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return strconv.FormatFloat(i.(float64), 'f', -1, 64), true
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case int:
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return strconv.FormatInt(int64(i.(int)), 10), true
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case []byte:
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return string(s), true
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case nil:
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return "", true
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default:
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jww.ERROR.Printf("Unable to Cast %#v to string", i)
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}
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return "", false
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}
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func ToStringMapStringE(i interface{}) (map[string]string, bool) {
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var m = map[string]string{}
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@ -98,79 +176,6 @@ func ToStringSliceE(i interface{}) ([]string, bool) {
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return a, true
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}
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func ToFloat64E(i interface{}) (float64, bool) {
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switch s := i.(type) {
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case float64:
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return s, true
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case float32:
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return float64(s), true
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case string:
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v, err := strconv.ParseFloat(s, 64)
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if err == nil {
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return float64(v), true
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} else {
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jww.ERROR.Printf("Unable to Cast %#v to float", i)
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jww.ERROR.Println(err)
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}
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default:
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jww.ERROR.Printf("Unable to Cast %#v to float", i)
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}
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return 0.0, false
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}
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func ToIntE(i interface{}) (int, bool) {
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switch s := i.(type) {
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case int:
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return s, true
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case int64:
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return int(s), true
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case int32:
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return int(s), true
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case int16:
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return int(s), true
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case int8:
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return int(s), true
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case string:
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v, err := strconv.ParseInt(s, 0, 0)
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if err == nil {
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return int(v), true
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} else {
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jww.ERROR.Printf("Unable to Cast %#v to int", i)
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jww.ERROR.Println(err)
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}
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case bool:
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if bool(s) {
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return 1, true
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} else {
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return 0, true
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}
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default:
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jww.ERROR.Printf("Unable to Cast %#v to int", i)
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}
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return 0, false
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}
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func ToStringE(i interface{}) (string, bool) {
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switch s := i.(type) {
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case string:
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return s, true
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case float64:
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return strconv.FormatFloat(i.(float64), 'f', -1, 64), true
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case int:
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return strconv.FormatInt(int64(i.(int)), 10), true
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case nil:
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return "", true
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default:
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jww.ERROR.Printf("Unable to Cast %#v to string", i)
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}
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return "", false
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}
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func StringToDate(s string) (time.Time, error) {
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return parseDateWith(s, []string{
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time.RFC3339,
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