英文:
Can I pass a json object as value for a cli flag in go?
问题
我正在使用urfave/cli来编写我的Go程序，我想要一个CLI标志，用于读取像这样的JSON值：
{"name":"foo","surname":"var"}
我目前将该变量读取为cli.StringFlag，它返回一个字符串。然后，我计划使用json.Unmarshal对其进行解析，但是它不起作用。问题在于CLI库返回的字符串是这样的：
[{name foo} {surname var}]
这不再是一个JSON。
有没有办法实现这个？请注意，如果它返回一个简单的映射，那也可以。
英文:
I am using urfave/cli for my go program and I would like to have a cli flag that reads a json value like this one:
{"name":"foo","surname":"var"}
I am currently reading that variable as a cli.StringFlag which returns a string. Then, I was planning to json.Unmarshall it but it does not work. The problem is that the returned string by the cli library is like this:
[{name foo} {surname var}]
which is not a json anymore.
Is there a way to achieve this? Note that if it returned a simple map, that would work too
答案1
得分: 1
对于Linux系统，请尝试使用shell转义来传递参数：
#!/bin/bash
echo "{\"name\":\"foo\",\"surname\":\"var\"}"
在Go程序中，只需将此字符串参数进行编组（marshal）。
英文:
for Linux, try to pass the paramaters with shell escape
#!/bin/bash
echo "{\"name\":\"foo\",\"surname\":\"var\"}"
in go program, just marshal this string parameter
答案2
得分: 1
问题是，shell（bash、ksh、csh、zsh等）将以下内容解释为一系列的“裸字”和“带引号的字”标记：
| 标记类型 | 值 |
|---|---|
| 裸字 | { |
| 带引号的字 | name |
| 裸字 | : |
| 带引号的字 | foo |
| 裸字 | , |
| 带引号的字 | surname |
| 裸字 | : |
| 带引号的字 | var |
| 裸字 | } |
事实上，逗号（,）是一个用于算术运算的shell操作符，它基本上被丢弃了（至少在我使用的zsh中）。
然后将所有内容拼接在一起，得到
name:foo surname:var
你可以通过打开你的shell并执行以下命令来看到这个过程：
echo {"name":"foo","surname":"var"}
然而，如果你使用单引号（'）引用你的JSON文档：
echo ''{"name":"foo","surname":"var"}''
你将得到你所期望的结果：
{"name":"foo","surname":"var"}
然而，请注意，如果你的JSON文档中的文本包含一个字面上的撇号/单引号（'），那么这种方法将失败，所以你需要用\,来替换JSON文档中的所有这样的出现以进行转义。
英文:
The issue is that the shell (bash, ksh, csh, zsh, ...) interprets
{"name":"foo","surname":"var"}
as a sequence of bareword and quoted word tokens:
| Token Type | Value |
|---|---|
| bareword | { |
| quoted word | name |
| bareword | : |
| quoted word | foo |
| bareword | , |
| quoted word | surname |
| bareword | : |
| quoted word | var |
| bare word | } |
As it happens, a comma (,) is a shell operator, used for arithmetic, and that essentially gets discarded (at least in zsh, what I use).
The whole is then spliced together to get
name:foo surname:var
You can see this in action by opening your shell and executing the command
echo {"name":"foo","surname":"var"}
If, however, you quote your JSON document with single quotes ('):
echo '{"name":"foo","surname":"var"}'
You'll get what you might expect:
{"name":"foo","surname":"var"}
Note, however, that this will fail if the text in your JSON document contains a literal apostrophe/single quote (', U+0027), so you'd want to replace all such occurrences within the JSON document with \, to escape them.
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