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jsonpath user guide docs

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Dai Zuozhuo
2015-08-13 16:31:38 +08:00
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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.
<strong>
The latest 1.0.x release of this document can be found
[here](http://releases.k8s.io/release-1.0/docs/user-guide/jsonpath.md).
Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
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# JSONPath template syntax
JSONPath template is composed of JSONPath expressions enclosed by {}.
And we add three functions in addition to the original JSONPath syntax:
1. The `$` operator is optional since the expression always start from the root object by default.
2. We can use `""` to quote text inside JSONPath expression.
3. We can use `range` operator to iterate list.
The result object is printed as its String() function.
Given the input:
```json
{
"kind": "List",
"items":[
{
"kind":"None",
"metadata":{"name":"127.0.0.1"},
"status":{
"capacity":{"cpu":"4"},
"addresses":[{"type": "LegacyHostIP", "address":"127.0.0.1"}]
}
},
{
"kind":"None",
"metadata":{"name":"127.0.0.2"},
"status":{
"capacity":{"cpu":"8"},
"addresses":[
{"type": "LegacyHostIP", "address":"127.0.0.2"},
{"type": "another", "address":"127.0.0.3"}
]
}
}
],
"users":[
{
"name": "myself",
"user": {}
},
{
"name": "e2e",
"user": {"username": "admin", "password": "secret"}
}
]
}
```
Function | Description | Example | Result
---------|--------------------|--------------------|------------------
text | the plain text | kind is {.kind} | kind is List
"" | quote | {"{"} | {
@ | the current object | {@} | the same as input
. or [] | child operator | {.kind} or {['kind']}| List
.. | recursive descent | {..name} | 127.0.0.1 127.0.0.2 myself e2e
* | wildcard. Get all objects| {.items[*].metadata.name} | [127.0.0.1 127.0.0.2]
[start:end :step] | subscript operator | {.users[0].name}| myself
[,] | union operator | {.items[*]['metadata.name', 'status.capacity']} | 127.0.0.1 127.0.0.2 map[cpu:4] map[cpu:8]
?() | filter | {.users[?(@.name=="e2e")].user.password} | secret
range, end | iterate list | {range .items[*]}[{.metadata.name}, {.status.capacity}] {end} | [127.0.0.1, map[cpu:4]] [127.0.0.2, map[cpu:8]]
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