有没有办法在 html/template 中执行以下操作？

{{template "mytemplate" struct{Foo1, Foo2 string}{"Bar1", "Bar2"}}}

实际上在模板中，如上。不是通过在返回结构的 FuncMap 中注册的函数。

我试过了，但是 Parse 崩溃了，see Playground .也许只是语法错误？

最佳答案

正如其他人所指出的，这是不可能的。模板在运行时解析，无需 Go 编译器的帮助。因此，允许任意 Go 语法是不可行的(尽管请注意，这并非不可能，因为标准库包含解析 Go 源文本的所有工具，请参阅标准库中“前缀为”go/ 的包)。根据设计理念，复杂的逻辑应该在模板之外。

回到你的例子:

struct{Foo1, Foo2 string}{"Bar1", "Bar2"}

这是一个结构 composite literal它在模板中不受支持，无论是在调用另一个模板时还是在其他地方。

使用自定义“参数”调用另一个模板具有以下语法(引用自 text/template: Actions ):

{{template "name" pipeline}}
    The template with the specified name is executed with dot set
    to the value of the pipeline.

TL;DR; 管道可以是一个常量，一个表示某个字段或方法的表达式(方法将被调用并使用其返回值)，它可能是调用某些“模板内置”函数或自定义注册函数，或映射中的值。

在哪里Pipeline是:

A pipeline is a possibly chained sequence of "commands". A command is a simple value (argument) or a function or method call, possibly with multiple arguments:

Argument
  The result is the value of evaluating the argument.
.Method [Argument...]
  The method can be alone or the last element of a chain but,
  unlike methods in the middle of a chain, it can take arguments.
  The result is the value of calling the method with the
  arguments:
      dot.Method(Argument1, etc.)
functionName [Argument...]
  The result is the value of calling the function associated
  with the name:
      function(Argument1, etc.)
  Functions and function names are described below.

还有一个 Argument是:

An argument is a simple value, denoted by one of the following.

- A boolean, string, character, integer, floating-point, imaginary
  or complex constant in Go syntax. These behave like Go's untyped
  constants. Note that, as in Go, whether a large integer constant
  overflows when assigned or passed to a function can depend on whether
  the host machine's ints are 32 or 64 bits.
- The keyword nil, representing an untyped Go nil.
- The character '.' (period):
  .
  The result is the value of dot.
- A variable name, which is a (possibly empty) alphanumeric string
  preceded by a dollar sign, such as
  $piOver2
  or
  $
  The result is the value of the variable.
  Variables are described below.
- The name of a field of the data, which must be a struct, preceded
  by a period, such as
  .Field
  The result is the value of the field. Field invocations may be
  chained:
    .Field1.Field2
  Fields can also be evaluated on variables, including chaining:
    $x.Field1.Field2
- The name of a key of the data, which must be a map, preceded
  by a period, such as
  .Key
  The result is the map element value indexed by the key.
  Key invocations may be chained and combined with fields to any
  depth:
    .Field1.Key1.Field2.Key2
  Although the key must be an alphanumeric identifier, unlike with
  field names they do not need to start with an upper case letter.
  Keys can also be evaluated on variables, including chaining:
    $x.key1.key2
- The name of a niladic method of the data, preceded by a period,
  such as
  .Method
  The result is the value of invoking the method with dot as the
  receiver, dot.Method(). Such a method must have one return value (of
  any type) or two return values, the second of which is an error.
  If it has two and the returned error is non-nil, execution terminates
  and an error is returned to the caller as the value of Execute.
  Method invocations may be chained and combined with fields and keys
  to any depth:
    .Field1.Key1.Method1.Field2.Key2.Method2
  Methods can also be evaluated on variables, including chaining:
    $x.Method1.Field
- The name of a niladic function, such as
  fun
  The result is the value of invoking the function, fun(). The return
  types and values behave as in methods. Functions and function
  names are described below.
- A parenthesized instance of one the above, for grouping. The result
  may be accessed by a field or map key invocation.
  print (.F1 arg1) (.F2 arg2)
  (.StructValuedMethod "arg").Field

正确的解决方案是注册一个自定义函数，该函数构造要传递给模板调用的值，如您在相关/可能的副本中所见:Golang pass multiple values from template to template?

另一种半解决方案是使用内置的 print 或 printf 函数来连接您要传递的值，但这需要在另一个模板中拆分.

关于go - 匿名结构作为模板中的管道，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55105838/