Guard Get<Entity>ID helpers against count/empty-list panic (#103)

The generated Get<Entity>ID and Get<Entity>ByID helpers index the result slice at [0] as soon as Count == 1, without checking the slice is non-empty. When the API reports count >= 1 but returns an empty list (a count/slice mismatch seen e.g. on the metrics APIs), this panics with 'index out of range [0] with length 0' (issue #103). Fix the generator template (generate/generate.go) to emit a length guard before the [0] access, returning the same 'No match found' error already used for the count == 0 case, and apply it to the generated helpers (additive only). Adds a regression test that panics on the unpatched code and passes with the guard. Signed-off-by: James Peru <james@xcobean.com>
apache · jmsperu · Jun 20, 2026 · Jun 20, 2026 · 0287d08b5e8555962e085b0fefde87fa6a8517f3
commit 0287d08b5e8555962e085b0fefde87fa6a8517f3
diff --git a/cloudstack/AccountService.go b/cloudstack/AccountService.go
@@ -1804,6 +1804,9 @@ func (s *AccountService) GetAccountID(name string, opts ...OptionFunc) (string,
 	}
 
 	if l.Count == 1 {
+		if len(l.Accounts) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.Accounts[0].Id, l.Count, nil
 	}
 
@@ -1859,6 +1862,9 @@ func (s *AccountService) GetAccountByID(id string, opts ...OptionFunc) (*Account
 	}
 
 	if l.Count == 1 {
+		if len(l.Accounts) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Accounts[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Account UUID: %s!", id)
@@ -2232,6 +2238,9 @@ func (s *AccountService) GetProjectAccountID(keyword string, projectid string, o
 	}
 
 	if l.Count == 1 {
+		if len(l.ProjectAccounts) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", keyword, l)
+		}
 		return l.ProjectAccounts[0].Id, l.Count, nil
 	}
 

diff --git a/cloudstack/AddressService.go b/cloudstack/AddressService.go
@@ -1303,6 +1303,9 @@ func (s *AddressService) GetPublicIpAddressByID(id string, opts ...OptionFunc) (
 	}
 
 	if l.Count == 1 {
+		if len(l.PublicIpAddresses) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.PublicIpAddresses[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for PublicIpAddress UUID: %s!", id)

diff --git a/cloudstack/AffinityGroupService.go b/cloudstack/AffinityGroupService.go
@@ -897,6 +897,9 @@ func (s *AffinityGroupService) GetAffinityGroupID(name string, opts ...OptionFun
 	}
 
 	if l.Count == 1 {
+		if len(l.AffinityGroups) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.AffinityGroups[0].Id, l.Count, nil
 	}
 
@@ -956,6 +959,9 @@ func (s *AffinityGroupService) GetAffinityGroupByID(id string, opts ...OptionFun
 	}
 
 	if l.Count == 1 {
+		if len(l.AffinityGroups) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.AffinityGroups[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for AffinityGroup UUID: %s!", id)

diff --git a/cloudstack/AlertService.go b/cloudstack/AlertService.go
@@ -745,6 +745,9 @@ func (s *AlertService) GetAlertID(name string, opts ...OptionFunc) (string, int,
 	}
 
 	if l.Count == 1 {
+		if len(l.Alerts) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.Alerts[0].Id, l.Count, nil
 	}
 
@@ -800,6 +803,9 @@ func (s *AlertService) GetAlertByID(id string, opts ...OptionFunc) (*Alert, int,
 	}
 
 	if l.Count == 1 {
+		if len(l.Alerts) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Alerts[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Alert UUID: %s!", id)

diff --git a/cloudstack/AnnotationService.go b/cloudstack/AnnotationService.go
@@ -432,6 +432,9 @@ func (s *AnnotationService) GetAnnotationByID(id string, opts ...OptionFunc) (*A
 	}
 
 	if l.Count == 1 {
+		if len(l.Annotations) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Annotations[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Annotation UUID: %s!", id)

diff --git a/cloudstack/AutoScaleService.go b/cloudstack/AutoScaleService.go
@@ -2432,6 +2432,9 @@ func (s *AutoScaleService) GetAutoScalePolicyID(name string, opts ...OptionFunc)
 	}
 
 	if l.Count == 1 {
+		if len(l.AutoScalePolicies) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.AutoScalePolicies[0].Id, l.Count, nil
 	}
 
@@ -2487,6 +2490,9 @@ func (s *AutoScaleService) GetAutoScalePolicyByID(id string, opts ...OptionFunc)
 	}
 
 	if l.Count == 1 {
+		if len(l.AutoScalePolicies) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.AutoScalePolicies[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for AutoScalePolicy UUID: %s!", id)
@@ -2937,6 +2943,9 @@ func (s *AutoScaleService) GetAutoScaleVmGroupID(name string, opts ...OptionFunc
 	}
 
 	if l.Count == 1 {
+		if len(l.AutoScaleVmGroups) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.AutoScaleVmGroups[0].Id, l.Count, nil
 	}
 
@@ -2992,6 +3001,9 @@ func (s *AutoScaleService) GetAutoScaleVmGroupByID(id string, opts ...OptionFunc
 	}
 
 	if l.Count == 1 {
+		if len(l.AutoScaleVmGroups) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.AutoScaleVmGroups[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for AutoScaleVmGroup UUID: %s!", id)
@@ -3438,6 +3450,9 @@ func (s *AutoScaleService) GetAutoScaleVmProfileByID(id string, opts ...OptionFu
 	}
 
 	if l.Count == 1 {
+		if len(l.AutoScaleVmProfiles) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.AutoScaleVmProfiles[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for AutoScaleVmProfile UUID: %s!", id)
@@ -3803,6 +3818,9 @@ func (s *AutoScaleService) GetConditionByID(id string, opts ...OptionFunc) (*Con
 	}
 
 	if l.Count == 1 {
+		if len(l.Conditions) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Conditions[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Condition UUID: %s!", id)
@@ -4059,6 +4077,9 @@ func (s *AutoScaleService) GetCounterID(name string, opts ...OptionFunc) (string
 	}
 
 	if l.Count == 1 {
+		if len(l.Counters) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.Counters[0].Id, l.Count, nil
 	}
 
@@ -4114,6 +4135,9 @@ func (s *AutoScaleService) GetCounterByID(id string, opts ...OptionFunc) (*Count
 	}
 
 	if l.Count == 1 {
+		if len(l.Counters) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Counters[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Counter UUID: %s!", id)

diff --git a/cloudstack/BGPPeerService.go b/cloudstack/BGPPeerService.go
@@ -1010,6 +1010,9 @@ func (s *BGPPeerService) GetBgpPeerByID(id string, opts ...OptionFunc) (*BgpPeer
 	}
 
 	if l.Count == 1 {
+		if len(l.BgpPeers) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.BgpPeers[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for BgpPeer UUID: %s!", id)

diff --git a/cloudstack/BackupService.go b/cloudstack/BackupService.go
@@ -3151,6 +3151,9 @@ func (s *BackupService) GetBackupOfferingID(keyword string, opts ...OptionFunc)
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupOfferings) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", keyword, l)
+		}
 		return l.BackupOfferings[0].Id, l.Count, nil
 	}
 
@@ -3206,6 +3209,9 @@ func (s *BackupService) GetBackupOfferingByID(id string, opts ...OptionFunc) (*B
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupOfferings) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.BackupOfferings[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for BackupOffering UUID: %s!", id)
@@ -3389,6 +3395,9 @@ func (s *BackupService) GetBackupProviderOfferingID(keyword string, zoneid strin
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupProviderOfferings) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", keyword, l)
+		}
 		return l.BackupProviderOfferings[0].Id, l.Count, nil
 	}
 
@@ -3721,6 +3730,9 @@ func (s *BackupService) GetBackupRepositoryID(name string, opts ...OptionFunc) (
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupRepositories) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.BackupRepositories[0].Id, l.Count, nil
 	}
 
@@ -3776,6 +3788,9 @@ func (s *BackupService) GetBackupRepositoryByID(id string, opts ...OptionFunc) (
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupRepositories) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.BackupRepositories[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for BackupRepository UUID: %s!", id)
@@ -4108,6 +4123,9 @@ func (s *BackupService) GetBackupScheduleByID(id string, opts ...OptionFunc) (*B
 	}
 
 	if l.Count == 1 {
+		if len(l.BackupSchedule) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.BackupSchedule[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for BackupSchedule UUID: %s!", id)
@@ -4530,6 +4548,9 @@ func (s *BackupService) GetBackupID(name string, opts ...OptionFunc) (string, in
 	}
 
 	if l.Count == 1 {
+		if len(l.Backups) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.Backups[0].Id, l.Count, nil
 	}
 
@@ -4585,6 +4606,9 @@ func (s *BackupService) GetBackupByID(id string, opts ...OptionFunc) (*Backup, i
 	}
 
 	if l.Count == 1 {
+		if len(l.Backups) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Backups[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Backup UUID: %s!", id)

diff --git a/cloudstack/BrocadeVCSService.go b/cloudstack/BrocadeVCSService.go
@@ -428,6 +428,9 @@ func (s *BrocadeVCSService) GetBrocadeVcsDeviceNetworkID(keyword string, vcsdevi
 	}
 
 	if l.Count == 1 {
+		if len(l.BrocadeVcsDeviceNetworks) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", keyword, l)
+		}
 		return l.BrocadeVcsDeviceNetworks[0].Id, l.Count, nil
 	}
 

diff --git a/cloudstack/CertificateService.go b/cloudstack/CertificateService.go
@@ -573,6 +573,9 @@ func (s *CertificateService) GetTemplateDirectDownloadCertificateByID(id string,
 	}
 
 	if l.Count == 1 {
+		if len(l.TemplateDirectDownloadCertificates) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.TemplateDirectDownloadCertificates[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for TemplateDirectDownloadCertificate UUID: %s!", id)

diff --git a/cloudstack/ClusterService.go b/cloudstack/ClusterService.go
@@ -1898,6 +1898,9 @@ func (s *ClusterService) GetClusterID(name string, opts ...OptionFunc) (string,
 	}
 
 	if l.Count == 1 {
+		if len(l.Clusters) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.Clusters[0].Id, l.Count, nil
 	}
 
@@ -1953,6 +1956,9 @@ func (s *ClusterService) GetClusterByID(id string, opts ...OptionFunc) (*Cluster
 	}
 
 	if l.Count == 1 {
+		if len(l.Clusters) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.Clusters[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for Cluster UUID: %s!", id)
@@ -2191,6 +2197,9 @@ func (s *ClusterService) GetClusterDrsPlanByID(id string, opts ...OptionFunc) (*
 	}
 
 	if l.Count == 1 {
+		if len(l.ClusterDrsPlan) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.ClusterDrsPlan[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for ClusterDrsPlan UUID: %s!", id)
@@ -2609,6 +2618,9 @@ func (s *ClusterService) GetClustersMetricID(name string, opts ...OptionFunc) (s
 	}
 
 	if l.Count == 1 {
+		if len(l.ClustersMetrics) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.ClustersMetrics[0].Id, l.Count, nil
 	}
 
@@ -2664,6 +2676,9 @@ func (s *ClusterService) GetClustersMetricByID(id string, opts ...OptionFunc) (*
 	}
 
 	if l.Count == 1 {
+		if len(l.ClustersMetrics) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.ClustersMetrics[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for ClustersMetric UUID: %s!", id)

diff --git a/cloudstack/ConfigurationService.go b/cloudstack/ConfigurationService.go
@@ -1879,6 +1879,9 @@ func (s *ConfigurationService) GetCniConfigurationID(name string, opts ...Option
 	}
 
 	if l.Count == 1 {
+		if len(l.CniConfiguration) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.CniConfiguration[0].Id, l.Count, nil
 	}
 
@@ -1934,6 +1937,9 @@ func (s *ConfigurationService) GetCniConfigurationByID(id string, opts ...Option
 	}
 
 	if l.Count == 1 {
+		if len(l.CniConfiguration) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.CniConfiguration[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for CniConfiguration UUID: %s!", id)

diff --git a/cloudstack/DiskOfferingService.go b/cloudstack/DiskOfferingService.go
@@ -1445,6 +1445,9 @@ func (s *DiskOfferingService) GetDiskOfferingID(name string, opts ...OptionFunc)
 	}
 
 	if l.Count == 1 {
+		if len(l.DiskOfferings) == 0 {
+			return "", l.Count, fmt.Errorf("No match found for %s: %+v", name, l)
+		}
 		return l.DiskOfferings[0].Id, l.Count, nil
 	}
 
@@ -1500,6 +1503,9 @@ func (s *DiskOfferingService) GetDiskOfferingByID(id string, opts ...OptionFunc)
 	}
 
 	if l.Count == 1 {
+		if len(l.DiskOfferings) == 0 {
+			return nil, l.Count, fmt.Errorf("No match found for %s: %+v", id, l)
+		}
 		return l.DiskOfferings[0], l.Count, nil
 	}
 	return nil, l.Count, fmt.Errorf("There is more then one result for DiskOffering UUID: %s!", id)