chenrui
115 lines
5.0 KiB
Markdown
115 lines
5.0 KiB
Markdown
---
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title: JSONPath 支持
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---
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<!-- ---
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title: JSONPath Support
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--- -->
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<!-- JSONPath template is composed of JSONPath expressions enclosed by {}.
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And we add three functions in addition to the original JSONPath syntax: -->
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JSONPath 模板由 {} 包起来的 JSONPath 表达式组成。
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除了原始的 JSONPath 语法之外，我们还添加了三个函数：
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<!-- 1. The `$` operator is optional since the expression always starts from the root object by default.
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2. We can use `""` to quote text inside JSONPath expressions.
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3. We can use `range` operator to iterate lists.
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4. We can use negative slice indices to step backwards through a list. Negative indices do not "wrap around" a list. They are valid as long as `-index + listLength >= 0`. -->
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1. `$` 运算符是可选的，因为表达式默认情况下始终从根对象开始。
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2. 可以使用 `""` 来引用 JSONPath 表达式中的文本。
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3. 可以使用 `range` 运算符来遍历列表。
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4. 可以使用负切片索引来反向遍历列表。负索引并不会遍历完列表。它们只需要满足 `-index + listLength >= 0` 便可执行。
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<!-- The result object is printed as its String() function. -->
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结果对象使用 String() 函数打印。
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<!-- Given the input: -->
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给定输入：
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```json
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{
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"kind": "List",
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"items":[
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{
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"kind":"None",
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"metadata":{"name":"127.0.0.1"},
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"status":{
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"capacity":{"cpu":"4"},
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"addresses":[{"type": "LegacyHostIP", "address":"127.0.0.1"}]
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}
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},
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{
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"kind":"None",
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"metadata":{"name":"127.0.0.2"},
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"status":{
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"capacity":{"cpu":"8"},
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"addresses":[
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{"type": "LegacyHostIP", "address":"127.0.0.2"},
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{"type": "another", "address":"127.0.0.3"}
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]
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}
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}
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],
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"users":[
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{
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"name": "myself",
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"user": {}
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},
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{
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"name": "e2e",
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"user": {"username": "admin", "password": "secret"}
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}
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]
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}
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```
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<!-- Function | Description | Example | Result
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---------|--------------------|--------------------|------------------
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text | the plain text | kind is {.kind} | kind is List
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@ | the current object | {@} | the same as input
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. or [] | child operator | {.kind} or {['kind']}| List
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.. | recursive descent | {..name} | 127.0.0.1 127.0.0.2 myself e2e
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\* | wildcard. Get all objects| {.items[*].metadata.name} | [127.0.0.1 127.0.0.2]
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[start:end :step] | subscript operator | {.users[0].name}| myself
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[,] | union operator | {.items[*]['metadata.name', 'status.capacity']} | 127.0.0.1 127.0.0.2 map[cpu:4] map[cpu:8]
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?() | filter | {.users[?(@.name=="e2e")].user.password} | secret
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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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'' | quote interpreted string | {range .items[*]}{.metadata.name}{'\t'}{end} | 127.0.0.1 127.0.0.2 -->
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函数 | 描述 | 示例 | 结果
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---------|--------------------|--------------------|------------------
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text | 纯文本 | kind is {.kind} | kind 是 List
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@ | 当前对象 | {@} | 与输入相同
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. or [] | 子运算符 | {.kind} or {['kind']}| List
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.. | 递归下降 | {..name} | 127.0.0.1 127.0.0.2 myself e2e
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\* | 通配符，获取所有对象| {.items[*].metadata.name} | [127.0.0.1 127.0.0.2]
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[start:end :step] | 下标运算符 | {.users[0].name}| myself
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[,] | 并集运算符 | {.items[*]['metadata.name', 'status.capacity']} | 127.0.0.1 127.0.0.2 map[cpu:4] map[cpu:8]
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?() | 过滤器 | {.users[?(@.name=="e2e")].user.password} | secret
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range, end | 遍历列表 | {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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'' | 引用解释字符串 | {range .items[*]}{.metadata.name}{'\t'}{end} | 127.0.0.1 127.0.0.2
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<!-- Below are some examples using jsonpath: -->
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下面是使用 jsonpath 的一些例子：
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```shell
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$ kubectl get pods -o json
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$ kubectl get pods -o=jsonpath='{@}'
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$ kubectl get pods -o=jsonpath='{.items[0]}'
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$ kubectl get pods -o=jsonpath='{.items[0].metadata.name}'
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$ kubectl get pods -o=jsonpath='{range .items[*]}{.metadata.name}{"\t"}{.status.startTime}{"\n"}{end}'
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```
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<!-- On Windows, you must _double_ quote any JSONPath template that contains spaces (not single quote as shown above for bash). This in turn means that you must use a single quote or escaped double quote around any literals in the template. For example: -->
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在 Windows 上，你必须要 _双_ 引号（而不是上面 bash 例子中的单引号）来引用包含空格符的任何 JSONPath 模板。
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这也意味着，如果你要用字面值，必须要使用单引号或者转义双引号。例如：
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```cmd
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C:\> kubectl get pods -o=jsonpath="{range .items[*]}{.metadata.name}{'\t'}{.status.startTime}{'\n'}{end}"
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C:\> kubectl get pods -o=jsonpath="{range .items[*]}{.metadata.name}{\"\t\"}{.status.startTime}{\"\n\"}{end}"
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```
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