Unify error messages

entry.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -40,16 +39,16 @@ func (e *Entry) checkAuthors(authorInFeed bool) error {
 	if e.Authors == nil {
 		if !authorInFeed {
 			if e.Source == nil {
-				return errors.New("no authors set in entry")
+				return fmt.Errorf("no authors set in entry %v", e)
 			}
 			if e.Source.Authors == nil {
-				return errors.New("no authors set in entry")
+				return fmt.Errorf("no authors set in entry %v", e)
 			}
 		}
 	} else {
 		for i, a := range e.Authors {
 			if err := a.Check(); err != nil {
-				return fmt.Errorf("author element %v of entry: %v", i, err)
+				return fmt.Errorf("author element %v of entry %v: %v", i, e, err)
 			}
 		}
 	}
@@ -140,72 +139,72 @@ func (e *Entry) AddExtension(x *ExtensionElement) {
 // error.
 func (e *Entry) Check() error {
 	if e.ID == nil {
-		return errors.New("no id element of entry")
+		return fmt.Errorf("no id element of entry %v", e)
 	} else {
 		if err := e.ID.Check(); err != nil {
-			return fmt.Errorf("id element of entry: %v", err)
+			return fmt.Errorf("id element of entry %v: %v", e, err)
 		}
 	}
 
 	if err := e.checkAuthors(true); err != nil {
-		return fmt.Errorf("entry %v: %v", e.ID.URI, err)
+		return fmt.Errorf("entry %v: %v", e, err)
 	}
 
 	for i, c := range e.Categories {
 		if err := c.Check(); err != nil {
-			return fmt.Errorf("category element %v of entry %v: %v", i, e.ID.URI, err)
+			return fmt.Errorf("category element %v of entry %v: %v", i, e, err)
 		}
 	}
 
 	if e.Content != nil {
 		if err := e.Content.Check(); err != nil {
-			return fmt.Errorf("content element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("content element of entry %v: %v", e, err)
 		}
 	} else {
 		// atom:entry elements that contain no child atom:content element MUST
 		// contain at least one atom:link element with a rel attribute value of
 		// "alternate".
 		if !alternateRelExists(e.Links) {
-			return errors.New("no content element of entry %v and no link element with rel \"alternate\"")
+			return fmt.Errorf("no content element of entry %v and no link element with rel \"alternate\"", e)
 		}
 	}
 
 	for i, c := range e.Contributors {
 		if err := c.Check(); err != nil {
-			return fmt.Errorf("contributor element %v of entry %v: %v", i, e.ID.URI, err)
+			return fmt.Errorf("contributor element %v of entry %v: %v", i, e, err)
 		}
 	}
 
 	for i, l := range e.Links {
 		if err := l.Check(); err != nil {
-			return fmt.Errorf("link element %v of entry %v: %v", i, e.ID.URI, err)
+			return fmt.Errorf("link element %v of entry %v: %v", i, e, err)
 		}
 	}
 	if hasAlternateDuplicateLinks(e.Links) {
-		return fmt.Errorf("links with with a rel attribute value of \"alternate\" and duplicate type and hreflang attribute values found in entry %v", e.ID.URI)
+		return fmt.Errorf("links with a rel attribute value of \"alternate\" and duplicate type and hreflang attribute values found in entry %v", e)
 	}
 
 	if e.Published != nil {
 		if err := e.Published.Check(); err != nil {
-			return fmt.Errorf("published element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("published element of entry %v: %v", e, err)
 		}
 	}
 
 	if e.Rights != nil {
 		if err := e.Rights.Check(); err != nil {
-			return fmt.Errorf("rights element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("rights element of entry %v: %v", e, err)
 		}
 	}
 
 	if e.Source != nil {
 		if err := e.Source.Check(); err != nil {
-			return fmt.Errorf("source element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("source element of entry %v: %v", e, err)
 		}
 	}
 
 	if e.Summary != nil {
 		if err := e.Summary.Check(); err != nil {
-			return fmt.Errorf("summary element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("summary element of entry %v: %v", e, err)
 		}
 	} else {
 		// atom:entry elements MUST contain an atom:summary element in either
@@ -213,7 +212,7 @@ func (e *Entry) Check() error {
 		// the atom:entry contains an atom:content that has a "src" attribute
 		// (and is thus empty).
 		if e.Content.hasSRC() {
-			return fmt.Errorf("no summary element of entry %v but content of type out of line content", e.ID.URI)
+			return fmt.Errorf("no summary element of entry %v but content of type out of line content", e)
 		}
 		// the atom:entry contains content that is encoded in Base64; i.e., the
 		// "type" attribute of atom:content is a MIME media type [MIMEREG], but
@@ -221,29 +220,29 @@ func (e *Entry) Check() error {
 		// does not end with "/xml" or "+xml".
 		mediaType := e.Content.getType()
 		if isValidMediaType(mediaType) && !isXMLMediaType(mediaType) && !strings.HasPrefix(mediaType, "text/") {
-			return fmt.Errorf("no summary element of entry %v but media type not xml", e.ID.URI)
+			return fmt.Errorf("no summary element of entry %v but media type not xml", e)
 		}
 	}
 
 	if e.Title == nil {
-		return fmt.Errorf("no title element of entry %v", e.ID.URI)
+		return fmt.Errorf("no title element of entry %v", e)
 	} else {
 		if err := e.Title.Check(); err != nil {
-			return fmt.Errorf("title element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("title element of entry %v: %v", e, err)
 		}
 	}
 
 	if e.Updated == nil {
-		return fmt.Errorf("no updated element of entry %v", e.ID.URI)
+		return fmt.Errorf("no updated element of entry %v", e)
 	} else {
 		if err := e.Updated.Check(); err != nil {
-			return fmt.Errorf("updated element of entry %v: %v", e.ID.URI, err)
+			return fmt.Errorf("updated element of entry %v: %v", e, err)
 		}
 	}
 
 	for i, x := range e.Extensions {
 		if err := x.Check(); err != nil {
-			return fmt.Errorf("extension element %v of entry %v: %v", i, e.ID.URI, err)
+			return fmt.Errorf("extension element %v of entry %v: %v", i, e, err)
 		}
 	}