now we allow overriding multi-value headers.

README.markdown

@@ -289,12 +289,27 @@ Will yield
 
 in the response headers. Only array-like tables are accepted.
 
+Note that, for those standard headers that only accepts a single value, like Content-Type, only the last element
+in the (array) table will take effect. So
+
+    ngx.header.content_type = {'a', 'b'}
+
+is equivalent to
+
+    ngx.header.content_type = 'b'
+
 Setting a slot to nil effectively removes it from the response headers:
 
     ngx.header["X-My-Header"] = nil;
 
+same does assigning an empty table:
+
+    ngx.header["X-My-Header"] = {};
+
+Reading values from ngx.header.HEADER is not implemented yet.
+
 ngx.exec(uri, args)
-----------
+-------------------
 
 Does an internal redirect to uri with args.
 

src/ngx_http_lua_headers.c

@@ -153,7 +153,8 @@ ngx_http_set_header_helper(ngx_http_request_t *r, ngx_http_lua_header_val_t *hv,
                 *output_header = &h[i];
             }
 
-            return NGX_OK;
+            /* return NGX_OK; */
+            matched = 1;
         }
     }
 

t/016-headers.t

@@ -105,7 +105,7 @@ Hello
 
 
 
-=== TEST 6: set response content-type header
+=== TEST 6: set multi response content-type header
 --- config
     location /read {
         content_by_lua '
@@ -122,7 +122,7 @@ Hello
 
 
 
-=== TEST 6: set response content-type header
+=== TEST 7: set response content-type header
 --- config
     location /read {
         content_by_lua '
@@ -137,3 +137,57 @@ Content-Type: bc
 --- response_body
 Hello
 
+
+
+=== TEST 8: set multi response content-type header and clears it
+--- config
+    location /read {
+        content_by_lua '
+            ngx.header["X-Foo"] = {"a", "bc"}
+            ngx.header["X-Foo"] = {}
+            ngx.say("Hello")
+        ';
+    }
+--- request
+GET /read
+--- response_headers
+!X-Foo
+--- response_body
+Hello
+
+
+
+=== TEST 9: set multi response content-type header and clears it
+--- config
+    location /read {
+        content_by_lua '
+            ngx.header["X-Foo"] = {"a", "bc"}
+            ngx.header["X-Foo"] = nil
+            ngx.say("Hello")
+        ';
+    }
+--- request
+GET /read
+--- response_headers
+!X-Foo
+--- response_body
+Hello
+
+
+
+=== TEST 10: set multi response content-type header (multiple times)
+--- config
+    location /read {
+        content_by_lua '
+            ngx.header["X-Foo"] = {"a", "bc"}
+            ngx.header["X-Foo"] = {"a", "abc"}
+            ngx.say("Hello")
+        ';
+    }
+--- request
+GET /read
+--- raw_response_headers_like chomp
+X-Foo: a\r\n.*?X-Foo: abc$
+--- response_body
+Hello
+