Configurable query parameters parser (grpc-ecosystem#1138)

* grpc-ecosystem#1128 make it possible to configure query param parser implementation

* Apply suggestions from code review

Makes names more consistent and improves docs

Co-Authored-By: Johan Brandhorst <johan.brandhorst@gmail.com>

* grpc-ecosystem#1128 make configured parser a global parser

* update docs for configuring query parser

Co-Authored-By: Johan Brandhorst <johan.brandhorst@gmail.com>

* grpc-ecosystem#1128 unexport default query parameter parser and rename mux option

Co-authored-by: Johan Brandhorst <johan.brandhorst@gmail.com>

Fixes grpc-ecosystem#1128

runtime/mux.go

@@ -55,6 +55,15 @@ func WithForwardResponseOption(forwardResponseOption func(context.Context, http.
 	}
 }
 
+// SetQueryParameterParser sets the query parameter parser, used to populate message from query parameters.
+// Configuring this will mean the generated swagger output is no longer correct, and it should be
+// done with careful consideration.
+func SetQueryParameterParser(queryParameterParser QueryParameterParser) ServeMuxOption {
+	return func(serveMux *ServeMux) {
+		currentQueryParser = queryParameterParser
+	}
+}
+
 // HeaderMatcherFunc checks whether a header key should be forwarded to/from gRPC context.
 type HeaderMatcherFunc func(string) (string, bool)
 

runtime/query.go

@@ -17,9 +17,24 @@ import (
 
 var valuesKeyRegexp = regexp.MustCompile("^(.*)\\[(.*)\\]$")
 
-// PopulateQueryParameters populates "values" into "msg".
-// A value is ignored if its key starts with one of the elements in "filter".
+var currentQueryParser QueryParameterParser = &defaultQueryParser{}
+
+// QueryParameterParser defines interface for all query parameter parsers
+type QueryParameterParser interface {
+	Parse(msg proto.Message, values url.Values, filter *utilities.DoubleArray) error
+}
+
+// PopulateQueryParameters parses query parameters
+// into "msg" using current query parser
 func PopulateQueryParameters(msg proto.Message, values url.Values, filter *utilities.DoubleArray) error {
+	return currentQueryParser.Parse(msg, values, filter)
+}
+
+type defaultQueryParser struct{}
+
+// Parse populates "values" into "msg".
+// A value is ignored if its key starts with one of the elements in "filter".
+func (*defaultQueryParser) Parse(msg proto.Message, values url.Values, filter *utilities.DoubleArray) error {
 	for key, values := range values {
 		match := valuesKeyRegexp.FindStringSubmatch(key)
 		if len(match) == 3 {