Add test and docs for int workaround

assembly.go

@@ -140,9 +140,14 @@ type FileInfo struct {
 	Meta             map[string]interface{} `json:"meta"`
 }
 
+// Integer is a warpper around a normal int but has softer JSON parsing requirements.
+// It can be used in situations where a JSON value is not always a number. Then parsing
+// will not fail and a default value of 0 will be returned.
+// For more details see: https://github.com/transloadit/go-sdk/issues/26
 type Integer int
 
 func (i *Integer) UnmarshalJSON(text []byte) error {
+	// Try parsing as an integer and default to 0, if it fails.
 	n, err := strconv.Atoi(string(text))
 	if err != nil {
 		*i = 0

assembly_test.go

@@ -1,6 +1,7 @@
 package transloadit
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"strings"
@@ -232,3 +233,33 @@ func TestListAssemblies(t *testing.T) {
 		t.Fatal("wrong template name")
 	}
 }
+
+func TestInteger_MarshalJSON(t *testing.T) {
+	var info AssemblyInfo
+	err := json.Unmarshal([]byte(`{"bytes_expected":55}`), &info)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if info.BytesExpected != 55 {
+		t.Fatal("wrong integer parsed")
+	}
+
+	err = json.Unmarshal([]byte(`{"bytes_expected":null}`), &info)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if info.BytesExpected != 0 {
+		t.Fatal("wrong default value for null")
+	}
+
+	err = json.Unmarshal([]byte(`{"bytes_expected":""}`), &info)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if info.BytesExpected != 0 {
+		t.Fatal("wrong default value for string")
+	}
+}