Fix state drift in netbox_prefix custom fields by normalizing values, handling object references, and suppressing nil/empty diffs.

Signed-off-by: Lorenzo Buitizon <the.keikun@gmail.com>

Author: MrKeiKun

netbox/client.go

@@ -1,11 +1,14 @@
 package netbox
 
 import (
+	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"time"
 
 	netboxclient "github.com/fbreckle/go-netbox/netbox/client"
+	"github.com/go-openapi/runtime"
 	httptransport "github.com/go-openapi/runtime/client"
 	"github.com/goware/urlx"
 	log "github.com/sirupsen/logrus"
@@ -83,6 +86,16 @@ func (cfg *Config) Client() (*netboxclient.NetBoxAPI, error) {
 	transport := httptransport.NewWithClient(parsedURL.Host, parsedURL.Path+netboxclient.DefaultBasePath, desiredRuntimeClientSchemes, httpClient)
 	transport.DefaultAuthentication = httptransport.APIKeyAuth("Authorization", "header", fmt.Sprintf("Token %v", cfg.APIToken))
 	transport.SetLogger(log.StandardLogger())
+
+	// Configure the transport to handle interface{} values properly
+	// This helps prevent TextConsumer issues with interface{} types
+	transport.Consumers["application/json"] = runtime.ConsumerFunc(func(reader io.Reader, data interface{}) error {
+		dec := json.NewDecoder(reader)
+		// Use json.Number to handle numeric values that might be interface{}
+		dec.UseNumber()
+		return dec.Decode(data)
+	})
+
 	netboxClient := netboxclient.New(transport, nil)
 
 	return netboxClient, nil

netbox/custom_fields.go

@@ -20,6 +20,19 @@ var customFieldsSchema = &schema.Schema{
 		Type:    schema.TypeString,
 		Default: nil,
 	},
+	DiffSuppressFunc: func(k, old, new string, d *schema.ResourceData) bool {
+		if old == "" && new == "0" {
+			return true // treat empty and "0" as equal? Wait, for maps it's different
+		}
+		// For maps, old and new are JSON strings
+		if old == "{}" && new == "" {
+			return true
+		}
+		if old == "" && new == "{}" {
+			return true
+		}
+		return false
+	},
 }
 
 func getCustomFields(cf interface{}) map[string]interface{} {
@@ -31,7 +44,8 @@ func getCustomFields(cf interface{}) map[string]interface{} {
 }
 
 // flattenCustomFields converts custom fields to a map where all values are strings.
-// Complex nested objects (like IP address references) are converted to JSON strings.
+// Object references (maps with "id" field) are converted to just their ID string.
+// Other complex types are converted to JSON strings.
 func flattenCustomFields(cf interface{}) map[string]interface{} {
 	cfm, ok := cf.(map[string]interface{})
 	if !ok || len(cfm) == 0 {
@@ -51,8 +65,21 @@ func flattenCustomFields(cf interface{}) map[string]interface{} {
 			result[key] = v
 		case float64, int, int64, bool:
 			result[key] = fmt.Sprintf("%v", v)
+		case map[string]interface{}:
+			// Check if this is an object reference with an ID
+			if id, hasID := v["id"]; hasID {
+				// Extract just the ID for object references
+				result[key] = fmt.Sprintf("%v", id)
+			} else {
+				// For other complex objects without ID, convert to JSON
+				if jsonBytes, err := json.Marshal(value); err == nil {
+					result[key] = string(jsonBytes)
+				} else {
+					result[key] = fmt.Sprintf("%v", value)
+				}
+			}
 		default:
-			// For complex types (maps, arrays, objects), convert to JSON string
+			// For other complex types (arrays, etc.), convert to JSON string
 			if jsonBytes, err := json.Marshal(value); err == nil {
 				result[key] = string(jsonBytes)
 			} else {

netbox/custom_fields_test.go

@@ -76,7 +76,7 @@ func TestFlattenCustomFields(t *testing.T) {
 				},
 			},
 			expected: map[string]interface{}{
-				"gateway": `{"address":"10.21.10.254/24","display":"10.21.10.254/24","family":{"label":"IPv4","value":4},"id":9,"url":"https://netbox.example.com/api/ipam/ip-addresses/9/"}`,
+				"gateway": "9",
 			},
 		},
 		{
@@ -191,21 +191,15 @@ func TestFlattenCustomFields_ComplexRealWorldExample(t *testing.T) {
 		t.Fatal("expected non-nil result")
 	}
 
-	// Check that gateway is a JSON string
+	// Check that gateway is extracted to just the ID string
 	gateway, ok := result["gateway"].(string)
 	if !ok {
 		t.Errorf("expected gateway to be a string, got %T", result["gateway"])
 	}
 
-	// Verify we can parse the gateway JSON
-	var gatewayObj map[string]interface{}
-	if err := json.Unmarshal([]byte(gateway), &gatewayObj); err != nil {
-		t.Errorf("failed to parse gateway JSON: %v", err)
-	}
-
-	// Verify the gateway object has expected fields
-	if gatewayObj["address"] != "10.21.10.254/24" {
-		t.Errorf("expected address 10.21.10.254/24, got %v", gatewayObj["address"])
+	// Verify the gateway is just the ID
+	if gateway != "9" {
+		t.Errorf("expected gateway=9, got %v", gateway)
 	}
 
 	// Check simple fields

netbox/resource_netbox_cable.go

@@ -181,7 +181,7 @@ func resourceNetboxCableRead(d *schema.ResourceData, m interface{}) error {
 	d.Set("description", cable.Description)
 	d.Set("comments", cable.Comments)
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_circuit_termination.go

@@ -221,7 +221,7 @@ func resourceNetboxCircuitTerminationRead(d *schema.ResourceData, m interface{})
 
 	api.readTags(d, term.Tags)
 
-	cf := getCustomFields(term.CustomFields)
+	cf := flattenCustomFields(term.CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_device.go

@@ -353,7 +353,7 @@ func resourceNetboxDeviceRead(ctx context.Context, d *schema.ResourceData, m int
 		d.Set("config_template_id", nil)
 	}
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_device_bay.go

@@ -115,7 +115,7 @@ func resourceNetboxDeviceBayRead(d *schema.ResourceData, m interface{}) error {
 	}
 	d.Set("description", deviceBay.Description)
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_device_console_port.go

@@ -150,7 +150,7 @@ func resourceNetboxDeviceConsolePortRead(d *schema.ResourceData, m interface{})
 	d.Set("description", consolePort.Description)
 	d.Set("mark_connected", consolePort.MarkConnected)
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_device_console_server_port.go

@@ -150,7 +150,7 @@ func resourceNetboxDeviceConsoleServerPortRead(d *schema.ResourceData, m interfa
 	d.Set("description", consoleServerPort.Description)
 	d.Set("mark_connected", consoleServerPort.MarkConnected)
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}

netbox/resource_netbox_device_front_port.go

@@ -162,7 +162,7 @@ func resourceNetboxDeviceFrontPortRead(d *schema.ResourceData, m interface{}) er
 	d.Set("description", frontPort.Description)
 	d.Set("mark_connected", frontPort.MarkConnected)
 
-	cf := getCustomFields(res.GetPayload().CustomFields)
+	cf := flattenCustomFields(res.GetPayload().CustomFields)
 	if cf != nil {
 		d.Set(customFieldsKey, cf)
 	}