Allow to use encoding/json with some Search APIs

This is a first trial of allowing to serialize the DSL objects with
`encoding/json`. They could then be used together with the official
client.

search_queries_match_all.go

@@ -4,6 +4,8 @@
 
 package elastic
 
+import "encoding/json"
+
 // MatchAllQuery is the most simple query, which matches all documents,
 // giving them all a _score of 1.0.
 //
@@ -34,7 +36,7 @@ func (q *MatchAllQuery) QueryName(name string) *MatchAllQuery {
 }
 
 // Source returns JSON for the match all query.
-func (q MatchAllQuery) Source() (interface{}, error) {
+func (q *MatchAllQuery) Source() (interface{}, error) {
 	// {
 	//   "match_all" : { ... }
 	// }
@@ -49,3 +51,15 @@ func (q MatchAllQuery) Source() (interface{}, error) {
 	}
 	return source, nil
 }
+
+// MarshalJSON enables serializing the type as JSON.
+func (q *MatchAllQuery) MarshalJSON() ([]byte, error) {
+	if q == nil {
+		return nilByte, nil
+	}
+	src, err := q.Source()
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(src)
+}

search_queries_match_all_test.go

@@ -59,3 +59,16 @@ func TestMatchAllQueryWithQueryName(t *testing.T) {
 		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
 	}
 }
+
+func TestMatchAllMarshalJSON(t *testing.T) {
+	in := NewMatchAllQuery().Boost(3.14)
+	data, err := json.Marshal(in)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := string(data)
+	expected := `{"match_all":{"boost":3.14}}`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}

search_source.go

@@ -5,6 +5,7 @@
 package elastic
 
 import (
+	"encoding/json"
 	"fmt"
 )
 
@@ -632,6 +633,18 @@ func (s *SearchSource) Source() (interface{}, error) {
 	return source, nil
 }
 
+// MarshalJSON enables serializing the type as JSON.
+func (q *SearchSource) MarshalJSON() ([]byte, error) {
+	if q == nil {
+		return nilByte, nil
+	}
+	src, err := q.Source()
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(src)
+}
+
 // -- IndexBoosts --
 
 // IndexBoost specifies an index by some boost factor.

search_source_test.go

@@ -27,6 +27,19 @@ func TestSearchSourceMatchAllQuery(t *testing.T) {
 	}
 }
 
+func TestSearchSourceMarshalJSON(t *testing.T) {
+	matchAllQ := NewMatchAllQuery()
+	builder := NewSearchSource().Query(matchAllQ)
+	data, err := builder.MarshalJSON()
+	if err != nil {
+		t.Fatalf("marshaling to JSON failed: %v", err)
+	}
+	got := string(data)
+	expected := `{"query":{"match_all":{}}}`
+	if got != expected {
+		t.Errorf("expected\n%s\n,got:\n%s", expected, got)
+	}
+}
 func TestSearchSourceNoStoredFields(t *testing.T) {
 	matchAllQ := NewMatchAllQuery()
 	builder := NewSearchSource().Query(matchAllQ).NoStoredFields()