语法: ngx.req.append_body(data_chunk)
环境: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*
向已存在的请求体中追加写入 data_chunk 参数指定的新数据块，此请求体最初使用 ngx.req.init_body 创建。
当请求体数据过大，不再能保存在内存缓冲区中时，数据将被写入一个临时文件，类似 Nginx 内核中的标准请求体处理方式。
需要强调的是，在当前请求的所有请求体被写入完成后，必须调用 ngx.req.finish_body 以结束写入。
此函数可以与 ngx.req.init_body，ngx.req.finish_body，和 ngx.req.socket 一起，使用纯 Lua 语言实现高效的输入过滤器 (在 rewrite_by_lua* 或 access_by_lua* 环境中)，与其他 Nginx 内容处理程序或上游模块例如 ngx_http_proxy_module 和 ngx_http_fastcgi_module 配合使用。
这个函数在 v0.5.11 版本中首次引入。
更多用法请参考 ngx.req.init_body。
English Source
syntax: ngx.req.append_body(data_chunk)
context: set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*
Append new data chunk specified by the data_chunk argument onto the existing request body created by the ngx.req.init_body call.
When the data can no longer be hold in the memory buffer for the request body, then the data will be flushed onto a temporary file just like the standard request body reader in the Nginx core.
It is important to always call the ngx.req.finish_body after all the data has been appended onto the current request body.
This function can be used with ngx.req.init_body, ngx.req.finish_body, and ngx.req.socket to implement efficient input filters in pure Lua (in the context of rewrite_by_lua* or access_by_lua*), which can be used with other Nginx content handler or upstream modules like ngx_http_proxy_module and ngx_http_fastcgi_module.
This function was first introduced in the v0.5.11 release.
See also ngx.req.init_body.