ngx.header.HEADER ----------------- **语法:** *ngx.header.HEADER = VALUE* **语法:** *value = ngx.header.HEADER* **环境:** *rewrite_by_lua*\**, access_by_lua*\**, content_by_lua*\**, header_filter_by_lua*\**, body_filter_by_lua, log_by_lua*\* 修改、添加、或清除当前请求待发送的 `HEADER` 响应头信息。 头名称中的下划线 (`_`) 将被默认替换为连字符 (`-`)。可以通过 [lua_transform_underscores_in_response_headers](#lua_transform_underscores_in_response_headers) 指令关闭这个替换。 头名称大小写不敏感。 ```lua -- 与 ngx.header["Content-Type"] = 'text/plain' 相同 ngx.header.content_type = 'text/plain'; ngx.header["X-My-Header"] = 'blah blah'; ``` 多值头信息可以按以下方法设置： ```lua ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'} ``` 在响应头中将输出： ```bash Set-Cookie: a=32; path=/ Set-Cookie: b=4; path=/ ``` 只接受 Lua 表输入 (对于类似 `Content-Type` 之类的只接受一个值的标准头信息，只有 Lua 表中的最后一个元素有效)。 ```lua ngx.header.content_type = {'a', 'b'} ``` 等同于 ```lua ngx.header.content_type = 'b' ``` 将一个头信息的值设为 `nil` 将从响应头中移除该输出： ```lua ngx.header["X-My-Header"] = nil; ``` 赋值一个空 Lua 表效果相同： ```lua ngx.header["X-My-Header"] = {}; ``` 在输出响应头 (不管是显示的通过 [ngx.send_headers](#ngxsend_headers) 或隐式的通过类似 [ngx.print](#ngxprint) 指令) 以后设置 `ngx.header.HEADER` 将抛出 Lua 异常。 读取 `ngx.header.HEADER` 将返回响应头中名为 `HEADER` 的头信息的值。 读取时，头名称中的下划线 (`_`) 也会被替换成连字符 (`-`)，并且大小写不敏感。如果该头信息不存在，将返回 `nil`。 这个 API 在 [header_filter_by_lua](#header_filter_by_lua) 和 [header_filter_by_lua_file](#header_filter_by_lua_file) 环境中非常有用，例如： ```nginx location /test { set $footer ''; proxy_pass http://some-backend; header_filter_by_lua ' if ngx.header["X-My-Header"] == "blah" then ngx.var.footer = "some value" end '; echo_after_body $footer; } ``` 对于多值头信息，所有值将被按顺序放入一个 Lua 表中，例如，响应头 Foo: bar Foo: baz 在读取 `ngx.header.Foo` 时返回的结果为 ```lua {"bar", "baz"} ``` 需要注意的是，`ngx.header` 不是一个标准 Lua 表，不能通过 Lua 的 `ipairs` 函数进行迭代查询。 读取 *请求* 头信息，请使用 [ngx.req.get_headers](#ngxreqget_headers) 函数。 > English Source **syntax:** *ngx.header.HEADER = VALUE* **syntax:** *value = ngx.header.HEADER* **context:** *rewrite_by_lua*\**, access_by_lua*\**, content_by_lua*\**, header_filter_by_lua*\**, body_filter_by_lua, log_by_lua*\* Set, add to, or clear the current request's `HEADER` response header that is to be sent. Underscores (`_`) in the header names will be replaced by hyphens (`-`) by default. This transformation can be turned off via the [lua_transform_underscores_in_response_headers](#lua_transform_underscores_in_response_headers) directive. The header names are matched case-insensitively. ```lua -- equivalent to ngx.header["Content-Type"] = 'text/plain' ngx.header.content_type = 'text/plain'; ngx.header["X-My-Header"] = 'blah blah'; ``` Multi-value headers can be set this way: ```lua ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'} ``` will yield ```bash Set-Cookie: a=32; path=/ Set-Cookie: b=4; path=/ ``` in the response headers. Only Lua tables are accepted (Only the last element in the table will take effect for standard headers such as `Content-Type` that only accept a single value). ```lua ngx.header.content_type = {'a', 'b'} ``` is equivalent to ```lua ngx.header.content_type = 'b' ``` Setting a slot to `nil` effectively removes it from the response headers: ```lua ngx.header["X-My-Header"] = nil; ``` The same applies to assigning an empty table: ```lua ngx.header["X-My-Header"] = {}; ``` Setting `ngx.header.HEADER` after sending out response headers (either explicitly with [ngx.send_headers](#ngxsend_headers) or implicitly with [ngx.print](#ngxprint) and similar) will throw out a Lua exception. Reading `ngx.header.HEADER` will return the value of the response header named `HEADER`. Underscores (`_`) in the header names will also be replaced by dashes (`-`) and the header names will be matched case-insensitively. If the response header is not present at all, `nil` will be returned. This is particularly useful in the context of [header_filter_by_lua](#header_filter_by_lua) and [header_filter_by_lua_file](#header_filter_by_lua_file), for example, ```nginx location /test { set $footer ''; proxy_pass http://some-backend; header_filter_by_lua ' if ngx.header["X-My-Header"] == "blah" then ngx.var.footer = "some value" end '; echo_after_body $footer; } ``` For multi-value headers, all of the values of header will be collected in order and returned as a Lua table. For example, response headers Foo: bar Foo: baz will result in ```lua {"bar", "baz"} ``` to be returned when reading `ngx.header.Foo`. Note that `ngx.header` is not a normal Lua table and as such, it is not possible to iterate through it using the Lua `ipairs` function. For reading *request* headers, use the [ngx.req.get_headers](#ngxreqget_headers) function instead. [返回目录](#nginx-api-for-lua)