JSON 格式
Redis 的 JSON 支持
Redis Stack 的 JSON 功能为 Redis 提供 JavaScript 对象表示法 （JSON） 支持。它允许您在 Redis 数据库中存储、更新和检索 JSON 值，类似于任何其他 Redis 数据类型。Redis JSON 还可以与 Redis 查询引擎无缝协作，让您能够为 JSON 文档编制索引和查询。
主要特点
- 完全支持 JSON 标准
- 用于选择/更新文档内元素的 JSONPath 语法（请参阅 JSONPath 语法)
- 文档以树状结构存储为二进制数据，允许快速访问子元素
- 所有 JSON 值类型的类型化原子作
将 Redis 与 JSON 结合使用
第一个要尝试的 JSON 命令是JSON.SET，它使用 JSON 值设置 Redis 键。JSON.SET接受所有 JSON 值类型。此示例创建一个 JSON 字符串：
Note how the commands include the dollar sign character $. This is the path to the value in the JSON document (in this case it just means the root).
Here are a few more string operations. JSON.STRLEN tells you the length of the string, and you can append another string to it with JSON.STRAPPEND.
Numbers can be incremented and multiplied:
Here's a more interesting example that includes JSON arrays and objects:
The JSON.DEL command deletes any JSON value you specify with the path parameter.
You can manipulate arrays with a dedicated subset of JSON commands:
JSON objects also have their own commands:
Format CLI output
The CLI has a raw output mode that lets you add formatting to the output from
JSON.GET to make
it more readable. To use this, run redis-cli with the --raw option
and include formatting keywords such as INDENT, NEWLINE, and SPACE
with JSON.GET:
$ redis-cli --raw
> JSON.GET obj INDENT "\t" NEWLINE "\n" SPACE " " $
[
{
"name": "Leonard Cohen",
"lastSeen": 1478476800,
"loggedOut": true
}
]
Enable Redis JSON
Redis JSON is not available by default in the basic Redis server, so you
should install Redis Stack or Redis Enterprise,
both of which include JSON and other useful modules.
See
Install Redis Stack or
Install Redis Enterprise
for full installation instructions.
Limitation
A JSON value passed to a command can have a depth of up to 128. If you pass to a command a JSON value that contains an object or an array with a nesting level of more than 128, the command returns an error.
Further information
Read the other pages in this section to learn more about Redis JSON
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