未验证 提交 a6ab1a5c 编写于 作者: L Linhe Huo 提交者: GitHub

[TD-12474]<docs>(connector): json type instructions in python (#9340)

上级 b866f7bd
......@@ -749,6 +749,49 @@ conn.execute("drop database pytest")
conn.close()
```
#### JSON 类型
`taospy` `v2.2.0` 开始,Python连接器开始支持 JSON 数据类型的标签(TDengine版本要求 Beta 版 2.3.5+, 稳定版 2.4.0+)。
创建一个使用JSON类型标签的超级表及其子表:
```python
# encoding:UTF-8
import taos
conn = taos.connect()
conn.execute("create database if not exists py_test_json_type")
conn.execute("use py_test_json_type")
conn.execute("create stable s1 (ts timestamp, v1 int) tags (info json)")
conn.execute("create table s1_1 using s1 tags ('{\"k1\": \"v1\"}')")
```
查询子表标签及表名:
```python
tags = conn.query("select info, tbname from s1").fetch_all_into_dict()
tags
```
`tags` 内容为:
```python
[{'info': '{"k1":"v1"}', 'tbname': 's1_1'}]
```
获取 JSON 中某值:
```python
k1 = conn.query("select info->'k1' as k1 from s1").fetch_all_into_dict()
"""
>>> k1
[{'k1': '"v1"'}]
"""
```
更多JSON类型的操作方式请参考 [JSON 类型使用说明](https://www.taosdata.com/cn/documentation/taos-sql)
#### 关于纳秒 (nanosecond) 在 Python 连接器中的说明
由于目前 Python 对 nanosecond 支持的不完善(参见链接 1. 2. ),目前的实现方式是在 nanosecond 精度时返回整数,而不是 ms 和 us 返回的 datetime 类型,应用开发者需要自行处理,建议使用 pandas 的 to_datetime()。未来如果 Python 正式完整支持了纳秒,涛思数据可能会修改相关接口。
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......@@ -575,6 +575,49 @@ Close connection.
conn.close()
```
#### JSON Type Support
Python connector `taospy` starts supporting JSON type as tags since `v2.2.0` (requires TDengine beta v2.3.5+, or stable v2.4.0+).
Create stable and table with JSON tag.
```python
# encoding:UTF-8
import taos
conn = taos.connect()
conn.execute("create database if not exists py_test_json_type")
conn.execute("use py_test_json_type")
conn.execute("create stable s1 (ts timestamp, v1 int) tags (info json)")
conn.execute("create table s1_1 using s1 tags ('{\"k1\": \"v1\"}')")
```
Query JSON tag and table name from a stable.
```python
tags = conn.query("select info, tbname from s1").fetch_all_into_dict()
tags
```
The `tags` value is:
```python
[{'info': '{"k1":"v1"}', 'tbname': 's1_1'}]
```
To get value from JSON tag by key:
```python
k1 = conn.query("select info->'k1' as k1 from s1").fetch_all_into_dict()
"""
>>> k1
[{'k1': '"v1"'}]
"""
```
Refer to [JSON type instructions](https://www.taosdata.com/en/documentation/taos-sql) for more usage of JSON type.
#### Using nanosecond in Python connector
So far Python still does not completely support nanosecond type. Please refer to the link 1 and 2. The implementation of the python connector is to return an integer number for nanosecond value rather than datatime type as what ms and us do. The developer needs to handle it themselves. We recommend using pandas to_datetime() function. If Python officially support nanosecond in the future, TAOS Data might be possible to change the interface accordingly, which mean the application need change too.
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