Add generic object retrieval

Now that the minimum Go version has been raised to 1.1 we can use
generics. This allows us to simplify a lot of the GetXXX calls to use
common code and avoid a lot of duplication.

Signed-off-by: Sean McGinnis <[email protected]>

common/collection.go

@@ -139,29 +139,32 @@ func CollectCollection(get func(string), links []string) {
 	wg.Wait()
 }
 
-func GetCollectionObjects[E any](c Client, link string, getFn func(Client, string) (*E, error)) ([]*E, error) {
-	var result []*E
-	if link == "" {
+func GetCollectionObjects[T any, PT interface {
+	*T
+	SchemaObject
+}](c Client, uri string) ([]*T, error) {
+	var result []*T
+	if uri == "" {
 		return result, nil
 	}
 
 	type GetResult struct {
-		Item  *E
+		Item  *T
 		Link  string
 		Error error
 	}
 
 	ch := make(chan GetResult)
 	collectionError := NewCollectionError()
 	get := func(link string) {
-		entity, err := getFn(c, link)
+		entity, err := GetObject[T, PT](c, link)
 		ch <- GetResult{Item: entity, Link: link, Error: err}
 	}
 
 	go func() {
-		err := CollectList(get, c, link)
+		err := CollectList(get, c, uri)
 		if err != nil {
-			collectionError.Failures[link] = err
+			collectionError.Failures[uri] = err
 		}
 		close(ch)
 	}()
@@ -174,8 +177,6 @@ func GetCollectionObjects[E any](c Client, link string, getFn func(Client, strin
 		}
 	}
 
-	fmt.Printf("Got here, %d objects in collection\n", len(result))
-
 	if collectionError.Empty() {
 		return result, nil
 	}

common/entity.go

@@ -42,6 +42,11 @@ func (e *Entity) SetClient(c Client) {
 	e.client = c
 }
 
+// SetETag sets the etag value of this API object.
+func (e *Entity) SetETag(tag string) {
+	e.etag = tag
+}
+
 // GetClient get the API client connection to use for accessing this
 // entity.
 func (e *Entity) GetClient() Client {
@@ -242,3 +247,32 @@ func getPatchPayloadFromUpdate(originalEntity, updatedEntity reflect.Value) (pay
 	}
 	return payload
 }
+
+type SchemaObject interface {
+	SetClient(Client)
+	SetETag(string)
+}
+
+// GetObject retrieves an API object from the service.
+func GetObject[T any, PT interface {
+	*T
+	SchemaObject
+}](c Client, uri string) (*T, error) {
+	resp, err := c.Get(uri)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	entity := PT(new(T))
+	err = json.NewDecoder(resp.Body).Decode(&entity)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.Header["Etag"] != nil {
+		entity.SetETag(resp.Header["Etag"][0])
+	}
+	entity.SetClient(c)
+	return entity, nil
+}

redfish/accelerationfunction.go

@@ -103,26 +103,13 @@ func (accelerationfunction *AccelerationFunction) UnmarshalJSON(b []byte) error
 
 // GetAccelerationFunction will get a AccelerationFunction instance from the service.
 func GetAccelerationFunction(c common.Client, uri string) (*AccelerationFunction, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var accelerationfunction AccelerationFunction
-	err = json.NewDecoder(resp.Body).Decode(&accelerationfunction)
-	if err != nil {
-		return nil, err
-	}
-
-	accelerationfunction.SetClient(c)
-	return &accelerationfunction, nil
+	return common.GetObject[AccelerationFunction](c, uri)
 }
 
 // ListReferencedAccelerationFunctions gets the collection of AccelerationFunction from
 // a provided reference.
 func ListReferencedAccelerationFunctions(c common.Client, link string) ([]*AccelerationFunction, error) {
-	return common.GetCollectionObjects(c, link, GetAccelerationFunction)
+	return common.GetCollectionObjects[AccelerationFunction](c, link)
 }
 
 // Endpoints gets the endpoints connected to this accelerator.

redfish/accountservice.go

@@ -476,8 +476,7 @@ func (accountservice *AccountService) Update() error {
 // GetAccountService will get the AccountService instance from the Redfish
 // service.
 func GetAccountService(c common.Client, uri string) (*AccountService, error) {
-	var accountService AccountService
-	return &accountService, accountService.Get(c, uri, &accountService)
+	return common.GetObject[AccountService](c, uri)
 }
 
 // Accounts get the accounts from the account service

redfish/addresspool.go

@@ -79,26 +79,13 @@ func (addresspool *AddressPool) UnmarshalJSON(b []byte) error {
 
 // GetAddressPool will get a AddressPool instance from the service.
 func GetAddressPool(c common.Client, uri string) (*AddressPool, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var addresspool AddressPool
-	err = json.NewDecoder(resp.Body).Decode(&addresspool)
-	if err != nil {
-		return nil, err
-	}
-
-	addresspool.SetClient(c)
-	return &addresspool, nil
+	return common.GetObject[AddressPool](c, uri)
 }
 
 // ListReferencedAddressPools gets the collection of AddressPool from
 // a provided reference.
 func ListReferencedAddressPools(c common.Client, link string) ([]*AddressPool, error) {
-	return common.GetCollectionObjects(c, link, GetAddressPool)
+	return common.GetCollectionObjects[AddressPool](c, link)
 }
 
 // Endpoints gets the endpoints connected to this address pool.

redfish/aggregate.go

@@ -134,24 +134,11 @@ func (aggregate *Aggregate) SetDefaultBootOrder() error {
 
 // GetAggregate will get a Aggregate instance from the service.
 func GetAggregate(c common.Client, uri string) (*Aggregate, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var aggregate Aggregate
-	err = json.NewDecoder(resp.Body).Decode(&aggregate)
-	if err != nil {
-		return nil, err
-	}
-
-	aggregate.SetClient(c)
-	return &aggregate, nil
+	return common.GetObject[Aggregate](c, uri)
 }
 
 // ListReferencedAggregates gets the collection of Aggregate from
 // a provided reference.
 func ListReferencedAggregates(c common.Client, link string) ([]*Aggregate, error) {
-	return common.GetCollectionObjects(c, link, GetAggregate)
+	return common.GetCollectionObjects[Aggregate](c, link)
 }

redfish/aggregationservice.go

@@ -144,24 +144,11 @@ func (aggregationservice *AggregationService) Update() error {
 
 // GetAggregationService will get a AggregationService instance from the service.
 func GetAggregationService(c common.Client, uri string) (*AggregationService, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var aggregationservice AggregationService
-	err = json.NewDecoder(resp.Body).Decode(&aggregationservice)
-	if err != nil {
-		return nil, err
-	}
-
-	aggregationservice.SetClient(c)
-	return &aggregationservice, nil
+	return common.GetObject[AggregationService](c, uri)
 }
 
 // ListReferencedAggregationServices gets the collection of AggregationService from
 // a provided reference.
 func ListReferencedAggregationServices(c common.Client, link string) ([]*AggregationService, error) {
-	return common.GetCollectionObjects(c, link, GetAggregationService)
+	return common.GetCollectionObjects[AggregationService](c, link)
 }

redfish/aggregationsource.go

@@ -190,26 +190,13 @@ func (aggregationsource *AggregationSource) Update() error {
 
 // GetAggregationSource will get a AggregationSource instance from the service.
 func GetAggregationSource(c common.Client, uri string) (*AggregationSource, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var aggregationsource AggregationSource
-	err = json.NewDecoder(resp.Body).Decode(&aggregationsource)
-	if err != nil {
-		return nil, err
-	}
-
-	aggregationsource.SetClient(c)
-	return &aggregationsource, nil
+	return common.GetObject[AggregationSource](c, uri)
 }
 
 // ListReferencedAggregationSources gets the collection of AggregationSource from
 // a provided reference.
 func ListReferencedAggregationSources(c common.Client, link string) ([]*AggregationSource, error) {
-	return common.GetCollectionObjects(c, link, GetAggregationSource)
+	return common.GetCollectionObjects[AggregationSource](c, link)
 }
 
 // SNMPSettings shall contain the settings for an SNMP aggregation source.

redfish/allowdeny.go

@@ -127,24 +127,11 @@ func (allowdeny *AllowDeny) Update() error {
 
 // GetAllowDeny will get a AllowDeny instance from the service.
 func GetAllowDeny(c common.Client, uri string) (*AllowDeny, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var allowdeny AllowDeny
-	err = json.NewDecoder(resp.Body).Decode(&allowdeny)
-	if err != nil {
-		return nil, err
-	}
-
-	allowdeny.SetClient(c)
-	return &allowdeny, nil
+	return common.GetObject[AllowDeny](c, uri)
 }
 
 // ListReferencedAllowDenys gets the collection of AllowDeny from
 // a provided reference.
 func ListReferencedAllowDenys(c common.Client, link string) ([]*AllowDeny, error) {
-	return common.GetCollectionObjects(c, link, GetAllowDeny)
+	return common.GetCollectionObjects[AllowDeny](c, link)
 }

redfish/application.go

@@ -75,26 +75,13 @@ func (application *Application) UnmarshalJSON(b []byte) error {
 
 // GetApplication will get a Application instance from the service.
 func GetApplication(c common.Client, uri string) (*Application, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var application Application
-	err = json.NewDecoder(resp.Body).Decode(&application)
-	if err != nil {
-		return nil, err
-	}
-
-	application.SetClient(c)
-	return &application, nil
+	return common.GetObject[Application](c, uri)
 }
 
 // ListReferencedApplications gets the collection of Application from
 // a provided reference.
 func ListReferencedApplications(c common.Client, link string) ([]*Application, error) {
-	return common.GetCollectionObjects(c, link, GetApplication)
+	return common.GetCollectionObjects[Application](c, link)
 }
 
 // SoftwareImage returns a `SoftwareInventory“ that represents the software image from which this application runs.

redfish/assembly.go

@@ -73,14 +73,13 @@ func (assembly *Assembly) Update() error {
 
 // GetAssembly will get a Assembly instance from the service.
 func GetAssembly(c common.Client, uri string) (*Assembly, error) {
-	var assembly Assembly
-	return &assembly, assembly.Get(c, uri, &assembly)
+	return common.GetObject[Assembly](c, uri)
 }
 
 // ListReferencedAssemblys gets the collection of Assembly from
 // a provided reference.
 func ListReferencedAssemblys(c common.Client, link string) ([]*Assembly, error) {
-	return common.GetCollectionObjects(c, link, GetAssembly)
+	return common.GetCollectionObjects[Assembly](c, link)
 }
 
 // AssemblyData is information about an assembly.

redfish/attributeregistry.go

@@ -306,6 +306,5 @@ type AttributeRegistry struct {
 // GetAttributeRegistry will get an AttributeRegistry instance from the Redfish service,
 // e.g. BiosAttributeRegistry
 func GetAttributeRegistry(c common.Client, uri string) (*AttributeRegistry, error) {
-	var attributeRegistry AttributeRegistry
-	return &attributeRegistry, attributeRegistry.Get(c, uri, &attributeRegistry)
+	return common.GetObject[AttributeRegistry](c, uri)
 }

redfish/battery.go

@@ -188,26 +188,13 @@ func (battery *Battery) Update() error {
 
 // GetBattery will get a Battery instance from the service.
 func GetBattery(c common.Client, uri string) (*Battery, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var battery Battery
-	err = json.NewDecoder(resp.Body).Decode(&battery)
-	if err != nil {
-		return nil, err
-	}
-
-	battery.SetClient(c)
-	return &battery, nil
+	return common.GetObject[Battery](c, uri)
 }
 
 // ListReferencedBatterys gets the collection of Battery from
 // a provided reference.
 func ListReferencedBatterys(c common.Client, link string) ([]*Battery, error) {
-	return common.GetCollectionObjects(c, link, GetBattery)
+	return common.GetCollectionObjects[Battery](c, link)
 }
 
 // Assembly get the containing assembly of this battery.

redfish/batterymetrics.go

@@ -5,8 +5,6 @@
 package redfish
 
 import (
-	"encoding/json"
-
 	"github.com/stmcginnis/gofish/common"
 )
 
@@ -72,24 +70,11 @@ type BatteryMetrics struct {
 
 // GetBatteryMetrics will get a BatteryMetrics instance from the service.
 func GetBatteryMetrics(c common.Client, uri string) (*BatteryMetrics, error) {
-	resp, err := c.Get(uri)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	var batterymetrics BatteryMetrics
-	err = json.NewDecoder(resp.Body).Decode(&batterymetrics)
-	if err != nil {
-		return nil, err
-	}
-
-	batterymetrics.SetClient(c)
-	return &batterymetrics, nil
+	return common.GetObject[BatteryMetrics](c, uri)
 }
 
 // ListReferencedBatteryMetricss gets the collection of BatteryMetrics from
 // a provided reference.
 func ListReferencedBatteryMetricss(c common.Client, link string) ([]*BatteryMetrics, error) {
-	return common.GetCollectionObjects(c, link, GetBatteryMetrics)
+	return common.GetCollectionObjects[BatteryMetrics](c, link)
 }