Can you update params_test.go with a test case for this situation ? thanks..

Confused.. The fixed should overwrite all other params, but all other params need to be arrays ?

@notzippy This situation is not only params but also include route, binder, controller. So I don't know how to write this situation's test case... sorry.

@pedromorgan Because first element of array is used to controller's arguments. So just like as I said above, Route parameters and Form parameters also can be overwritten with Query parameters. (Sorry for Get in I said above, it's a mistake of Query)
problem of #1095 isn't fixed yet and I think this patch fixes it.

If all params(Query, Form, Route and Fixed) need to append to array, I think that it should change the order of appending parameters (it's discussed in #503 ).

Would this be better ? So highest gets the first slot but lower ones can be promoted...

	for k, v := range p.Fixed {
-		values[k] = append(values[k], v...)
+		values[k] = append(v, values[k]...)
 	}

Alternatively I suggest here instead of this PR.

        // Copy everything into a param map,
-       // order of priority is least to most trusted
+       // order of priority is most to least trusted
        values := make(url.Values, numParams)

-       // ?query vars first
-       for k, v := range p.Query {
+       // fixed vars first
+       for k, v := range p.Fixed {
                values[k] = append(values[k], v...)
        }
-       // form vars overwrite
-       for k, v := range p.Form {
+       // :/path vars append
+       for k, v := range p.Route {
                values[k] = append(values[k], v...)
        }
-       // :/path vars overwrite
-       for k, v := range p.Route {
+       // form vars append
+       for k, v := range p.Form {
                values[k] = append(values[k], v...)
        }
-       // fixed vars overwrite
-       for k, v := range p.Fixed {
+       // ?query vars append
+       for k, v := range p.Query {
                values[k] = append(values[k], v...)
        }

What about a hybrid approach ? Since fixed and route parameters should never be set using query or form values they always do a replace, and query and form parameters are appended together.

	// ?query vars are first
	for k, v := range p.Query {
		values[k] = append(values[k], v...)
	}
    
	// form vars append so query first, form second
	for k, v := range p.Form {
		values[k] = append(values[k], v...)
	}
    
	// :/path vars overwrite and any above variables over written with path
	for k, v := range p.Route {
		values[k] = v 
	}
    
	// fixed vars overwrite, finaly rewrite all above values with the fixed ones
	for k, v := range p.Fixed {
		values[k] = v 
	}

@notzippy Yes that is what we want.. All query/post etc vars appended.. BUT a fixed one is CONST ;-) ta.. commit it bro...

Need to update manual to explain this problem.. and also a new CORS chapter.. ;-)

@pedromorgan I think with this PR #1171 you may need to rewrite the manual :-P
I incorporated this change in there..

Closing in favor of the above defined hybrid approach to be released with PR #1171. Thanks for everyone's effort on this!