Plugins: allow returning known error values as string (#14451)

provider/helper.go

@@ -3,6 +3,7 @@ package provider
 import (
 	"fmt"
 
+	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/util"
 )
 
@@ -16,3 +17,17 @@ func setFormattedValue(message, param string, v interface{}) (string, error) {
 		param: v,
 	})
 }
+
+// knownErrors maps string responses to known error codes
+func knownErrors(b []byte) error {
+	switch string(b) {
+	case "ErrAsleep":
+		return api.ErrAsleep
+	case "ErrMustRetry":
+		return api.ErrMustRetry
+	case "ErrNotAvailable":
+		return api.ErrNotAvailable
+	default:
+		return nil
+	}
+}

provider/http.go

@@ -168,6 +168,11 @@ func (p *HTTP) request(url string, body string) ([]byte, error) {
 		}
 
 		p.val, p.err = p.DoBody(req)
+		if p.err != nil {
+			if err := knownErrors(p.val); err != nil {
+				p.err = err
+			}
+		}
 		p.updated = time.Now()
 	}
 

provider/mqtt_handler.go

@@ -27,6 +27,10 @@ func (h *msgHandler) hasValue() (string, error) {
 		return "", err
 	}
 
+	if err := knownErrors([]byte(payload)); err != nil {
+		return "", err
+	}
+
 	if h.pipeline != nil {
 		b, err := h.pipeline.Process([]byte(payload))
 		return string(b), err

provider/socket.go

@@ -152,7 +152,15 @@ var _ StringProvider = (*Socket)(nil)
 func (p *Socket) StringGetter() (func() (string, error), error) {
 	return func() (string, error) {
 		val, err := p.val.Get()
-		return string(val), err
+		if err != nil {
+			return "", err
+		}
+
+		if err := knownErrors(val); err != nil {
+			return "", err
+		}
+
+		return string(val), nil
 	}, nil
 }