Use a custom type for RecordNotFound errors

db/database.go

@@ -1,7 +1,7 @@
 package db
 
 import (
-	"errors"
+	"fmt"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
@@ -23,6 +23,21 @@ type DynamodbDatabase struct {
 	Table      string
 }
 
+// RecordNotFound is an error type returned when no record was returnd from the database
+type RecordNotFound struct {
+	ID      *string
+	Version *string
+}
+
+// Error returns the string representation of the error.
+// satisfying the error interface
+func (e RecordNotFound) Error() string {
+	if e.Version != nil {
+		return fmt.Sprintf("Unable to find record for %s with version: %s", *e.ID, *e.Version)
+	}
+	return fmt.Sprintf("Unable to find record for %s", *e.ID)
+}
+
 // Connect creates a dynamodb connection
 func Connect(session *session.Session, dynamodbEndpoint string) *dynamodb.DynamoDB {
 	dynamoConfig := &aws.Config{Endpoint: aws.String(dynamodbEndpoint)}
@@ -35,8 +50,9 @@ func (d *DynamodbDatabase) query(params *dynamodb.QueryInput) (*datautils.Resour
 	if err != nil {
 		return nil, err
 	}
+
 	if len(resp.Items) == 0 {
-		return nil, errors.New("not found")
+		return nil, &RecordNotFound{}
 	}
 
 	return respToResource(resp.Items[0])

db/database_test.go

@@ -114,7 +114,16 @@ func TestRetrieveLatestNotFound(t *testing.T) {
 		t.Skip("skipping integration test in short mode")
 	}
 	_, err := initDatabase().RetrieveLatest("8888")
-	assert.NotNil(t, err)
+	assert.Equal(t, err.Error(), "Unable to find record for 8888")
+}
+
+func TestRetrieveVersionNotFound(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+	version := "9"
+	_, err := initDatabase().RetrieveVersion("8888", &version)
+	assert.Equal(t, err.Error(), "Unable to find record for 8888 with version: 9")
 }
 
 func initDatabase() Database {

db/delete.go

@@ -34,7 +34,7 @@ func (h *DynamodbDatabase) DeleteAllVersions(externalID string) error {
 			panic(err)
 		}
 		resource, err = h.RetrieveLatest(externalID)
-		if err != nil && err.Error() != "not found" {
+		if _, ok := err.(*RecordNotFound); !ok {
 			panic(err)
 		}
 	}

db/retrieve_latest.go

@@ -28,5 +28,9 @@ func (d *DynamodbDatabase) RetrieveLatest(externalID string) (*datautils.Resourc
 		TableName:        &d.Table,
 	}
 
-	return d.query(params)
+	result, err := d.query(params)
+	if tmp, ok := err.(*RecordNotFound); ok {
+		tmp.ID = &externalID
+	}
+	return result, err
 }

db/retrieve_version.go

@@ -34,5 +34,10 @@ func (d *DynamodbDatabase) RetrieveVersion(externalID string, version *string) (
 		TableName:        &d.Table,
 	}
 
-	return d.query(params)
+	result, err := d.query(params)
+	if tmp, ok := err.(*RecordNotFound); ok {
+		tmp.ID = &externalID
+		tmp.Version = version
+	}
+	return result, err
 }

handlers/retrieve_resource.go

@@ -31,7 +31,7 @@ func (d *retrieveResource) Handle(params operations.RetrieveResourceParams, agen
 	}
 
 	if err != nil {
-		if err.Error() == "not found" {
+		if _, ok := err.(*db.RecordNotFound); ok {
 			return operations.NewRetrieveResourceNotFound()
 		}
 		panic(err)

handlers/stub_database_test.go

@@ -47,7 +47,7 @@ func (d *MockDatabase) RetrieveLatest(externalID string) (*datautils.Resource, e
 		d.record = nil
 		return record, nil
 	}
-	return nil, errors.New("not found")
+	return nil, &db.RecordNotFound{ID: &externalID}
 }
 
 func (d *MockDatabase) RetrieveVersion(externalID string, version *string) (*datautils.Resource, error) {

handlers/update_resource.go

@@ -34,7 +34,7 @@ func (d *updateResourceEntry) Handle(params operations.UpdateResourceParams) mid
 
 	existingResource, err := d.database.RetrieveLatest(id)
 	if err != nil {
-		if err.Error() == "not found" {
+		if _, ok := err.(*db.RecordNotFound); ok {
 			return operations.NewUpdateResourceNotFound()
 		}
 		panic(err)