forked from mirror/sjson
278 lines
6.4 KiB
Markdown
278 lines
6.4 KiB
Markdown
<p align="center">
|
|
<img
|
|
src="logo.png"
|
|
width="240" height="78" border="0" alt="SJSON">
|
|
<br>
|
|
<a href="https://godoc.org/github.com/tidwall/sjson"><img src="https://img.shields.io/badge/api-reference-blue.svg?style=flat-square" alt="GoDoc"></a>
|
|
</p>
|
|
|
|
<p align="center">set a json value quickly</p>
|
|
|
|
SJSON is a Go package that provides a [very fast](#performance) and simple way to set a value in a json document. The purpose for this library is to provide efficient json updating for the [SummitDB](https://github.com/tidwall/summitdb) project.
|
|
For quickly retrieving json values check out [GJSON](https://github.com/tidwall/gjson).
|
|
|
|
For a command line interface check out [JJ](https://github.com/tidwall/jj).
|
|
|
|
Getting Started
|
|
===============
|
|
|
|
Installing
|
|
----------
|
|
|
|
To start using SJSON, install Go and run `go get`:
|
|
|
|
```sh
|
|
$ go get -u github.com/tidwall/sjson
|
|
```
|
|
|
|
This will retrieve the library.
|
|
|
|
Set a value
|
|
-----------
|
|
Set sets the value for the specified path.
|
|
A path is in dot syntax, such as "name.last" or "age".
|
|
This function expects that the json is well-formed and validated.
|
|
Invalid json will not panic, but it may return back unexpected results.
|
|
Invalid paths may return an error.
|
|
|
|
```go
|
|
package main
|
|
|
|
import "github.com/tidwall/sjson"
|
|
|
|
const json = `{"name":{"first":"Janet","last":"Prichard"},"age":47}`
|
|
|
|
func main() {
|
|
value, _ := sjson.Set(json, "name.last", "Anderson")
|
|
println(value)
|
|
}
|
|
```
|
|
|
|
This will print:
|
|
|
|
```json
|
|
{"name":{"first":"Janet","last":"Anderson"},"age":47}
|
|
```
|
|
|
|
Path syntax
|
|
-----------
|
|
|
|
A path is a series of keys separated by a dot.
|
|
The dot and colon characters can be escaped with ``\``.
|
|
|
|
```json
|
|
{
|
|
"name": {"first": "Tom", "last": "Anderson"},
|
|
"age":37,
|
|
"children": ["Sara","Alex","Jack"],
|
|
"fav.movie": "Deer Hunter",
|
|
"friends": [
|
|
{"first": "James", "last": "Murphy"},
|
|
{"first": "Roger", "last": "Craig"}
|
|
]
|
|
}
|
|
```
|
|
```
|
|
"name.last" >> "Anderson"
|
|
"age" >> 37
|
|
"children.1" >> "Alex"
|
|
"friends.1.last" >> "Craig"
|
|
```
|
|
|
|
The `-1` key can be used to append a value to an existing array:
|
|
|
|
```
|
|
"children.-1" >> appends a new value to the end of the children array
|
|
```
|
|
|
|
Normally number keys are used to modify arrays, but it's possible to force a numeric object key by using the colon character:
|
|
|
|
```json
|
|
{
|
|
"users":{
|
|
"2313":{"name":"Sara"},
|
|
"7839":{"name":"Andy"}
|
|
}
|
|
}
|
|
```
|
|
|
|
A colon path would look like:
|
|
|
|
```
|
|
"users.:2313.name" >> "Sara"
|
|
```
|
|
|
|
Supported types
|
|
---------------
|
|
|
|
Pretty much any type is supported:
|
|
|
|
```go
|
|
sjson.Set(`{"key":true}`, "key", nil)
|
|
sjson.Set(`{"key":true}`, "key", false)
|
|
sjson.Set(`{"key":true}`, "key", 1)
|
|
sjson.Set(`{"key":true}`, "key", 10.5)
|
|
sjson.Set(`{"key":true}`, "key", "hello")
|
|
sjson.Set(`{"key":true}`, "key", map[string]interface{}{"hello":"world"})
|
|
```
|
|
|
|
When a type is not recognized, SJSON will fallback to the `encoding/json` Marshaller.
|
|
|
|
|
|
Examples
|
|
--------
|
|
|
|
Set a value from empty document:
|
|
```go
|
|
value, _ := sjson.Set("", "name", "Tom")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"name":"Tom"}
|
|
```
|
|
|
|
Set a nested value from empty document:
|
|
```go
|
|
value, _ := sjson.Set("", "name.last", "Anderson")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"name":{"last":"Anderson"}}
|
|
```
|
|
|
|
Set a new value:
|
|
```go
|
|
value, _ := sjson.Set(`{"name":{"last":"Anderson"}}`, "name.first", "Sara")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"name":{"first":"Sara","last":"Anderson"}}
|
|
```
|
|
|
|
Update an existing value:
|
|
```go
|
|
value, _ := sjson.Set(`{"name":{"last":"Anderson"}}`, "name.last", "Smith")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"name":{"last":"Smith"}}
|
|
```
|
|
|
|
Set a new array value:
|
|
```go
|
|
value, _ := sjson.Set(`{"friends":["Andy","Carol"]}`, "friends.2", "Sara")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"friends":["Andy","Carol","Sara"]
|
|
```
|
|
|
|
Append an array value by using the `-1` key in a path:
|
|
```go
|
|
value, _ := sjson.Set(`{"friends":["Andy","Carol"]}`, "friends.-1", "Sara")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"friends":["Andy","Carol","Sara"]
|
|
```
|
|
|
|
Append an array value that is past the end:
|
|
```go
|
|
value, _ := sjson.Set(`{"friends":["Andy","Carol"]}`, "friends.4", "Sara")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"friends":["Andy","Carol",null,null,"Sara"]
|
|
```
|
|
|
|
Delete a value:
|
|
```go
|
|
value, _ := sjson.Delete(`{"name":{"first":"Sara","last":"Anderson"}}`, "name.first")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"name":{"last":"Anderson"}}
|
|
```
|
|
|
|
Delete an array value:
|
|
```go
|
|
value, _ := sjson.Delete(`{"friends":["Andy","Carol"]}`, "friends.1")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"friends":["Andy"]}
|
|
```
|
|
|
|
Delete the last array value:
|
|
```go
|
|
value, _ := sjson.Delete(`{"friends":["Andy","Carol"]}`, "friends.-1")
|
|
println(value)
|
|
|
|
// Output:
|
|
// {"friends":["Andy"]}
|
|
```
|
|
|
|
## Performance
|
|
|
|
Benchmarks of SJSON alongside [encoding/json](https://golang.org/pkg/encoding/json/),
|
|
[ffjson](https://github.com/pquerna/ffjson),
|
|
[EasyJSON](https://github.com/mailru/easyjson),
|
|
and [Gabs](https://github.com/Jeffail/gabs)
|
|
|
|
```
|
|
Benchmark_SJSON-8 3000000 805 ns/op 1077 B/op 3 allocs/op
|
|
Benchmark_SJSON_ReplaceInPlace-8 3000000 449 ns/op 0 B/op 0 allocs/op
|
|
Benchmark_JSON_Map-8 300000 21236 ns/op 6392 B/op 150 allocs/op
|
|
Benchmark_JSON_Struct-8 300000 14691 ns/op 1789 B/op 24 allocs/op
|
|
Benchmark_Gabs-8 300000 21311 ns/op 6752 B/op 150 allocs/op
|
|
Benchmark_FFJSON-8 300000 17673 ns/op 3589 B/op 47 allocs/op
|
|
Benchmark_EasyJSON-8 1500000 3119 ns/op 1061 B/op 13 allocs/op
|
|
```
|
|
|
|
JSON document used:
|
|
|
|
```json
|
|
{
|
|
"widget": {
|
|
"debug": "on",
|
|
"window": {
|
|
"title": "Sample Konfabulator Widget",
|
|
"name": "main_window",
|
|
"width": 500,
|
|
"height": 500
|
|
},
|
|
"image": {
|
|
"src": "Images/Sun.png",
|
|
"hOffset": 250,
|
|
"vOffset": 250,
|
|
"alignment": "center"
|
|
},
|
|
"text": {
|
|
"data": "Click Here",
|
|
"size": 36,
|
|
"style": "bold",
|
|
"vOffset": 100,
|
|
"alignment": "center",
|
|
"onMouseUp": "sun1.opacity = (sun1.opacity / 100) * 90;"
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
Each operation was rotated though one of the following search paths:
|
|
|
|
```
|
|
widget.window.name
|
|
widget.image.hOffset
|
|
widget.text.onMouseUp
|
|
```
|
|
|
|
*These benchmarks were run on a MacBook Pro 15" 2.8 GHz Intel Core i7 using Go 1.7 and can be be found [here](https://github.com/tidwall/sjson-benchmarks)*.
|
|
|
|
## Contact
|
|
Josh Baker [@tidwall](http://twitter.com/tidwall)
|
|
|
|
## License
|
|
|
|
SJSON source code is available under the MIT [License](/LICENSE).
|