Homematic: better error messages (evcc-io#6835)

meter/homematic/connection.go

@@ -84,10 +84,6 @@ func (c *Connection) XmlCmd(method, channel string, values ...Param) (MethodResp
 		return hmr, err
 	}
 
-	if strings.Contains(string(res), "faultCode") {
-		return hmr, fmt.Errorf("ccu: %s", string(res))
-	}
-
 	// correct Homematic IP Legacy API (CCU port 2010) method response encoding value
 	res = []byte(strings.Replace(string(res), "ISO-8859-1", "UTF-8", 1))
 
@@ -98,7 +94,7 @@ func (c *Connection) XmlCmd(method, channel string, values ...Param) (MethodResp
 		return hmr, err
 	}
 
-	return hmr, err
+	return hmr, parseError(hmr)
 }
 
 // Initialze CCU methods via system.listMethods call
@@ -149,3 +145,26 @@ func (c *Connection) GridTotalEnergy() (float64, error) {
 	res, err := c.XmlCmd("getValue", c.MeterChannel, Param{CCUString: "IEC_ENERGY_COUNTER"})
 	return res.Value.CCUFloat, err
 }
+
+// parseError checks on Homematic CCU error codes
+// Refer to page 30 of https://homematic-ip.com/sites/default/files/downloads/HM_XmlRpc_API.pdf
+func parseError(res MethodResponse) error {
+	var faultCode int64
+	var faultString string
+
+	faultCode = 0
+	for _, f := range res.Fault {
+		if f.Name == "faultCode" {
+			faultCode = f.Value.CCUInt
+		}
+		if f.Name == "faultString" {
+			faultString = f.Value.CCUString
+		}
+	}
+
+	if faultCode != 0 {
+		return fmt.Errorf("%s (%v)", faultString, faultCode)
+	}
+
+	return nil
+}

meter/homematic/types.go

@@ -21,7 +21,19 @@ type MethodCall struct {
 	Params     []Param  `xml:"params>param,omitempty"`
 }
 
+type Member struct {
+	Name  string     `xml:"name,omitempty"`
+	Value FaultValue `xml:"value,omitempty"`
+}
+
+type FaultValue struct {
+	XMLName   xml.Name `xml:"value"`
+	CCUString string   `xml:",chardata"`
+	CCUInt    int64    `xml:"i4,omitempty"`
+}
+
 type MethodResponse struct {
 	XMLName xml.Name `xml:"methodResponse"`
 	Value   Param    `xml:"params>param,omitempty"`
+	Fault   []Member `xml:"fault>value>struct>member,omitempty"`
 }

meter/homematic/types_test.go

@@ -0,0 +1,37 @@
+package homematic
+
+import (
+	"encoding/xml"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Test MethodResponse response
+func TestUnmarshalMethodResponse(t *testing.T) {
+
+	{
+		// Double response test
+		var res MethodResponse
+
+		xmlstr := `<?xml version="1.0" encoding="ISO-8859-1"?><methodResponse><params><param><value><double>20698.0</double></value></param></params></methodResponse>`
+		assert.NoError(t, xml.Unmarshal([]byte(strings.Replace(string(xmlstr), "ISO-8859-1", "UTF-8", 1)), &res))
+
+		assert.Equal(t, float64(20698), res.Value.CCUFloat)
+	}
+
+	{
+		// Faulty response test
+		var res MethodResponse
+
+		xmlstr := `<?xml version="1.0" encoding="ISO-8859-1"?><methodResponse><fault><value><struct><member><name>faultCode</name><value><i4>-2</i4></value></member><member><name>faultString</name><value>Invalid device</value></member></struct></value></fault></methodResponse>`
+		assert.NoError(t, xml.Unmarshal([]byte(strings.Replace(string(xmlstr), "ISO-8859-1", "UTF-8", 1)), &res))
+
+		assert.Equal(t, "faultCode", res.Fault[0].Name)
+		assert.Equal(t, int64(-2), res.Fault[0].Value.CCUInt)
+		assert.Equal(t, "faultString", res.Fault[1].Name)
+		assert.Equal(t, "Invalid device", res.Fault[1].Value.CCUString)
+	}
+
+}