3f5ecd6f42
Newer versions of aws-sdk-go contain a bugfix for retrieving region vs availability-zone information.
88 lines
2.9 KiB
Markdown
88 lines
2.9 KiB
Markdown
# go-jmespath - A JMESPath implementation in Go
|
|
|
|
[](https://travis-ci.org/jmespath/go-jmespath)
|
|
|
|
|
|
|
|
go-jmespath is a GO implementation of JMESPath,
|
|
which is a query language for JSON. It will take a JSON
|
|
document and transform it into another JSON document
|
|
through a JMESPath expression.
|
|
|
|
Using go-jmespath is really easy. There's a single function
|
|
you use, `jmespath.search`:
|
|
|
|
|
|
```go
|
|
> import "github.com/jmespath/go-jmespath"
|
|
>
|
|
> var jsondata = []byte(`{"foo": {"bar": {"baz": [0, 1, 2, 3, 4]}}}`) // your data
|
|
> var data interface{}
|
|
> err := json.Unmarshal(jsondata, &data)
|
|
> result, err := jmespath.Search("foo.bar.baz[2]", data)
|
|
result = 2
|
|
```
|
|
|
|
In the example we gave the ``search`` function input data of
|
|
`{"foo": {"bar": {"baz": [0, 1, 2, 3, 4]}}}` as well as the JMESPath
|
|
expression `foo.bar.baz[2]`, and the `search` function evaluated
|
|
the expression against the input data to produce the result ``2``.
|
|
|
|
The JMESPath language can do a lot more than select an element
|
|
from a list. Here are a few more examples:
|
|
|
|
```go
|
|
> var jsondata = []byte(`{"foo": {"bar": {"baz": [0, 1, 2, 3, 4]}}}`) // your data
|
|
> var data interface{}
|
|
> err := json.Unmarshal(jsondata, &data)
|
|
> result, err := jmespath.search("foo.bar", data)
|
|
result = { "baz": [ 0, 1, 2, 3, 4 ] }
|
|
|
|
|
|
> var jsondata = []byte(`{"foo": [{"first": "a", "last": "b"},
|
|
{"first": "c", "last": "d"}]}`) // your data
|
|
> var data interface{}
|
|
> err := json.Unmarshal(jsondata, &data)
|
|
> result, err := jmespath.search({"foo[*].first", data)
|
|
result [ 'a', 'c' ]
|
|
|
|
|
|
> var jsondata = []byte(`{"foo": [{"age": 20}, {"age": 25},
|
|
{"age": 30}, {"age": 35},
|
|
{"age": 40}]}`) // your data
|
|
> var data interface{}
|
|
> err := json.Unmarshal(jsondata, &data)
|
|
> result, err := jmespath.search("foo[?age > `30`]")
|
|
result = [ { age: 35 }, { age: 40 } ]
|
|
```
|
|
|
|
You can also pre-compile your query. This is usefull if
|
|
you are going to run multiple searches with it:
|
|
|
|
```go
|
|
> var jsondata = []byte(`{"foo": "bar"}`)
|
|
> var data interface{}
|
|
> err := json.Unmarshal(jsondata, &data)
|
|
> precompiled, err := Compile("foo")
|
|
> if err != nil{
|
|
> // ... handle the error
|
|
> }
|
|
> result, err := precompiled.Search(data)
|
|
result = "bar"
|
|
```
|
|
|
|
## More Resources
|
|
|
|
The example above only show a small amount of what
|
|
a JMESPath expression can do. If you want to take a
|
|
tour of the language, the *best* place to go is the
|
|
[JMESPath Tutorial](http://jmespath.org/tutorial.html).
|
|
|
|
One of the best things about JMESPath is that it is
|
|
implemented in many different programming languages including
|
|
python, ruby, php, lua, etc. To see a complete list of libraries,
|
|
check out the [JMESPath libraries page](http://jmespath.org/libraries.html).
|
|
|
|
And finally, the full JMESPath specification can be found
|
|
on the [JMESPath site](http://jmespath.org/specification.html).
|