fix: always send empty [] for locations (public/private) even when not set

If the backend does not receive a value, or receives a null value, it will
not update the database. This is an issue for many other values too, but
as an API level fix will be needed, for now this patch only addresses the
fields we've received reports about.

To make the patch a little easier, Create now calls CreateCheck, Update
UpdateCheck and Delete DeleteCheck. The latter two were already equivalent.
Create and CreateCheck had some differences (mainly that that former would
send the request to /v1/checks instead of /v1/checks/<type>), but given
how CreateCheck covers all check types, there should be no difference.

Author: sorccu

checkly.go

@@ -66,27 +66,7 @@ func (c *client) Create(
 	ctx context.Context,
 	check Check,
 ) (*Check, error) {
-	data, err := json.Marshal(check)
-	if err != nil {
-		return nil, err
-	}
-	status, res, err := c.apiCall(
-		ctx,
-		http.MethodPost,
-		withAutoAssignAlertsFlag("checks"),
-		data,
-	)
-	if err != nil {
-		return nil, err
-	}
-	if status != http.StatusCreated {
-		return nil, fmt.Errorf("unexpected response status %d: %q", status, res)
-	}
-	var result Check
-	if err = json.NewDecoder(strings.NewReader(res)).Decode(&result); err != nil {
-		return nil, fmt.Errorf("decoding error for data %s: %v", res, err)
-	}
-	return &result, nil
+	return c.CreateCheck(ctx, check)
 }
 
 // Update updates an existing check with the specified details. It returns the
@@ -98,28 +78,7 @@ func (c *client) Update(
 	ctx context.Context,
 	ID string, check Check,
 ) (*Check, error) {
-	data, err := json.Marshal(check)
-	if err != nil {
-		return nil, err
-	}
-	status, res, err := c.apiCall(
-		ctx,
-		http.MethodPut,
-		withAutoAssignAlertsFlag(fmt.Sprintf("checks/%s", ID)),
-		data,
-	)
-	if err != nil {
-		return nil, err
-	}
-	if status != http.StatusOK {
-		return nil, fmt.Errorf("unexpected response status %d: %q", status, res)
-	}
-	var result Check
-	err = json.NewDecoder(strings.NewReader(res)).Decode(&result)
-	if err != nil {
-		return nil, fmt.Errorf("decoding error for data %s: %v", res, err)
-	}
-	return &result, nil
+	return c.UpdateCheck(ctx, ID, check)
 }
 
 // Delete deletes the check with the specified ID.
@@ -130,19 +89,7 @@ func (c *client) Delete(
 	ctx context.Context,
 	ID string,
 ) error {
-	status, res, err := c.apiCall(
-		ctx,
-		http.MethodDelete,
-		fmt.Sprintf("checks/%s", ID),
-		nil,
-	)
-	if err != nil {
-		return err
-	}
-	if status != http.StatusNoContent {
-		return fmt.Errorf("unexpected response status %d: %q", status, res)
-	}
-	return nil
+	return c.DeleteCheck(ctx, ID)
 }
 
 // Get takes the ID of an existing check, and returns the check parameters, or
@@ -278,6 +225,14 @@ func (c *client) UpdateCheck(
 	ctx context.Context,
 	ID string, check Check,
 ) (*Check, error) {
+	// A nil value for a list will cause the backend to not update the value.
+	// We must send empty lists instead.
+	if check.Locations == nil {
+		check.Locations = []string{}
+	}
+	if check.PrivateLocations == nil {
+		check.PrivateLocations = &[]string{}
+	}
 	data, err := json.Marshal(check)
 	if err != nil {
 		return nil, err
@@ -337,6 +292,14 @@ func (c *client) UpdateTCPCheck(
 	ID string,
 	check TCPCheck,
 ) (*TCPCheck, error) {
+	// A nil value for a list will cause the backend to not update the value.
+	// We must send empty lists instead.
+	if check.Locations == nil {
+		check.Locations = []string{}
+	}
+	if check.PrivateLocations == nil {
+		check.PrivateLocations = &[]string{}
+	}
 	// Unfortunately `checkType` is required for this endpoint, so sneak it in
 	// using an anonymous struct.
 	payload := struct {
@@ -532,6 +495,14 @@ func (c *client) UpdateGroup(
 	ID int64,
 	group Group,
 ) (*Group, error) {
+	// A nil value for a list will cause the backend to not update the value.
+	// We must send empty lists instead.
+	if group.Locations == nil {
+		group.Locations = []string{}
+	}
+	if group.PrivateLocations == nil {
+		group.PrivateLocations = &[]string{}
+	}
 	data, err := json.Marshal(group)
 	if err != nil {
 		return nil, err