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explain Exists() function

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Josh Baker 2016-08-12 16:26:06 -07:00 committed by GitHub
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commit e865d89fc7
1 changed files with 23 additions and 11 deletions
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README.md
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@ -52,7 +52,7 @@ A path is a series of keys separated by a dot.
A key may contain special wildcard characters '\*' and '?'.
To access an array value use the index as the key.
To get the number of elements in an array use the '#' character.
The dot and wildcard character can be escaped with '\'.
The dot and wildcard characters can be escaped with '\'.
```
{
"name": {"first": "Tom", "last": "Anderson"},
@ -69,13 +69,12 @@ The dot and wildcard character can be escaped with '\'.
"fav\.movie" >> "Deer Hunter"
```
## Result Type
GJSON supports the json types `string`, `number`, `bool`, and `null`.
Arrays and Objects are returned as their raw json types.
The `Result` type holds one of these types:
The `Result` type holds one of these:
```
bool, for JSON booleans
@ -84,7 +83,7 @@ string, for JSON string literals
nil, for JSON null
```
To get the value call the `Value()` method:
To get the Go value call the `Value()` method:
```go
@ -92,15 +91,9 @@ result.Value() // interface{} which may be nil, string, float64, or bool
// Or just get the value in one step.
gjson.Get(json, "name.last").Value()
// Check for the existence of a value.
if gjson.Get(json, "name.last").Exists(){
println("value exists")
}
```
To directly access the value from its original type:
To directly access the value:
```go
result.Type // can be String, Number, True, False, Null, or JSON
@ -109,6 +102,25 @@ result.Num // holds the float64 number
result.Raw // holds the raw json
```
## Check for the existence of a value
Sometimes you may want to see if the value actually existed in the json document.
```
value := gjson.Get(json, "name.last")
if !value.Exists() {
println("no last name")
} else {
println(value.String())
}
// Or as one step
if gjson.Get(json, "name.last").Exists(){
println("has a last name")
}
```
## Performance
Benchmarks of GJSON alongside [encoding/json](https://golang.org/pkg/encoding/json/),