访问/api/test/demo接口，接口返回如下

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    "code":0,
    "msg":"成功success!",
    "data":[
            "age":20,
            "create_time":"2019-09-15",
            "id":1,
            "mail":"283340479@qq.com",
            "name":"yoyo",
            "sex":"M"
            "age":21,
            "create_time":"2019-09-16",
            "id":2,
            "mail":"123445@qq.com",
            "name":"yoyo111",
            "sex":"M"
validate 校验
1.提取data数据中name的值为yoyo的邮箱，并校验结果是：283340479@qq.com

2.提取data数据组中，年龄大于20的结果，并校验结果的数量是：1

先看第一个问题，有[]字符的时候
config:
    name: logincase
    base_url: http://127.0.0.1:8000
    variables: {}
teststeps:
    name: step1 login
    request:
        url: /api/test/demo
        method: GET
    validate:
        - eq: [status_code, 200]
        - eq: [body.data[?name=='yoyo'].mail, ["283340479@qq.com"]]
运行后结果 ：expected ',' or ']', but got '['
D:\demo>hrun demo.yml
2021-08-24 18:56:11.154 | INFO     | httprunner.make:__make:512 - make path: D:\demo\demo.yml
2021-08-24 18:56:11.158 | ERROR    | httprunner.loader:_load_yaml_file:36 - YAMLError:
file: D:\202108kecheng\demo\demo.yml
error: while parsing a flow sequence
  in "D:\202108kecheng\demo\demo.yml", line 13, column 15
expected ',' or ']', but got '['
  in "D:\202108kecheng\demo\demo.yml", line 13, column 25
2021-08-24 18:56:11.159 | WARNING  | httprunner.make:__make:530 - Invalid test file: D:\demo\demo.yml
FileFormatError:
2021-08-24 18:56:11.160 | INFO     | httprunner.make:format_pytest_with_black:170 - format pytest cases with black ...
No Path provided. Nothing to do 😴
2021-08-24 18:56:11.427 | ERROR    | httprunner.cli:main_run:49 - No valid testcases found, exit 1.
Sentry is attempting to send 0 pending error messages
Waiting up to 2 seconds
Press Ctrl-Break to quit
主要原因是，表达式 body.data[?name=='yoyo'].mail 里面有个 ] 符合，刚好跟httprunner3读取yaml文件语法冲突了

解决办法可以把表达式当一个字符串："body.data[?name=='yoyo'].mail"
    validate:
        - eq: [status_code, 200]
        - eq: ["body.data[?name=='yoyo'].mail", ["283340479@qq.com"]]
管道符 |
上面 jmespath 表达式 body.data[?name=='yoyo'].mail 取出来的值是list: ["283340479@qq.com"]

如果我们想取出字符串，拿字符串去校验可以继续取值，在结果中继续取值用管道符 |,然后下标取出第一个
    validate:
        - eq: [status_code, 200]
        - eq: ["body.data[?name=='yoyo'].mail|[0]", "283340479@qq.com"]
如果jmespath表达式过滤条件有数字类型的，判断age>20
    validate:
        - eq: [status_code, 200]
        - eq: ["body.length(data[?age>20])", 1]
此时会报错:ParseError,表达式不合法
E   jmespath.exceptions.ParseError: invalid token: Parse error at column 22, token "20" (NUMBER), for expression:
E   "body.length(data[?age>20])"
关于数字类型，需要在数字上加特殊字符 `20`
    validate:
        - eq: [status_code, 200]
        - eq: ["body.data[?name=='yoyo'].mail|[0]", "283340479@qq.com"]
        - eq: ["body.length(data[?age>`20`])", 1]
extract 提取结果
提取表达式body.data[?name=='yoyo'].mail|[0]的结果,用extract关键字
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config:
    name: logincase
    base_url: http://127.0.0.1:8000
    variables: {}
teststeps:
    name: step1 login
    request:
        url: /api/test/demo
        method: GET
    extract:
        mail: body.data[?name=='yoyo'].mail|[0]
    validate:
        - eq: [status_code, 200]
        - eq: ["body.data[?name=='yoyo'].mail|[0]", "283340479@qq.com"]
        - eq: ["body.length(data[?age>`20`])", 1]
这样直接提取会遇到一个问题，转成py代码的时候,单引号语法冲突了
           Step(RunRequest("step1 login")
                 .get("/api/test/demo")
                 .extract()
                 .with_jmespath('body.data[?name=='yoyo'].mail|[0]', 'mail')
但是jmespath 里面字符串只能用单引号，不能改成 body.data[?name=="yoyo"].mail|[0]

如果改成双引号，虽然语法上没有问题，但是提取不到结果： extract mapping: {'mail': None}
此处修改，可以用转义字符，在yaml文件中把单引号转成\'
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# blog地址 https://www.cnblogs.com/yoyoketang/
config:
    name: logincase
    base_url: http://127.0.0.1:8000
    variables: {}
teststeps:
    name: step1 login
    request:
        url: /api/test/demo
        method: GET
    extract:
        mail: body.data[?name==\'yoyo\'].mail|[0]
    validate:
        - eq: [status_code, 200]
        - eq: ["body.data[?name=='yoyo'].mail|[0]", "283340479@qq.com"]
        - eq: ["body.length(data[?age>`20`])", 1]
这样就可以达到效果了，运行日志可以看到取到了mail extract mapping: {'mail': '283340479@qq.com'}

转成对应的py脚本
from httprunner import HttpRunner, Config, Step, RunRequest, RunTestCase
class TestCaseDemo(HttpRunner):
    config = Config("logincase").base_url("http://127.0.0.1:8000")
    teststeps = [
        Step(
            RunRequest("step1 login")
            .get("/api/test/demo")
            .extract()
            .with_jmespath("body.data[?name=='yoyo'].mail|[0]", "mail")
            .validate()
            .assert_equal("status_code", 200)
            .assert_equal("body.data[?name=='yoyo'].mail|[0]", "283340479@qq.com")
            .assert_equal("body.length(data[?age>`20`])", 1)
if __name__ == "__main__":
    TestCaseDemo().test_start()
暂时遇到的问题就这些，可能还有其它问题
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