Fix backend linter errors

pkg/datasource/functions.go

@@ -145,6 +145,10 @@ func applyFunctionsPre(query *QueryModel, items []*zabbix.Item) error {
 
 func applyGroupBy(series timeseries.TimeSeries, params ...interface{}) (timeseries.TimeSeries, error) {
 	pInterval, err := MustString(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	pAgg, err := MustString(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -169,6 +173,10 @@ func applyGroupBy(series timeseries.TimeSeries, params ...interface{}) (timeseri
 
 func applyPercentile(series timeseries.TimeSeries, params ...interface{}) (timeseries.TimeSeries, error) {
 	pInterval, err := MustString(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	percentile, err := MustFloat64(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -275,6 +283,10 @@ func applyExponentialMovingAverage(series timeseries.TimeSeries, params ...inter
 
 func applyAggregateBy(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*timeseries.TimeSeriesData, error) {
 	pInterval, err := MustString(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	pAgg, err := MustString(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -303,6 +315,10 @@ func applySumSeries(series []*timeseries.TimeSeriesData, params ...interface{})
 
 func applyPercentileAgg(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*timeseries.TimeSeriesData, error) {
 	pInterval, err := MustString(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	percentile, err := MustFloat64(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -331,6 +347,10 @@ func applyPercentileAgg(series []*timeseries.TimeSeriesData, params ...interface
 
 func applyTop(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*timeseries.TimeSeriesData, error) {
 	n, err := MustFloat64(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	pAgg, err := MustString(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -343,6 +363,10 @@ func applyTop(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*ti
 
 func applyBottom(series []*timeseries.TimeSeriesData, params ...interface{}) ([]*timeseries.TimeSeriesData, error) {
 	n, err := MustFloat64(params[0])
+	if err != nil {
+		return nil, errParsingFunctionParam(err)
+	}
+
 	pAgg, err := MustString(params[1])
 	if err != nil {
 		return nil, errParsingFunctionParam(err)
@@ -413,7 +437,7 @@ func applyTimeShiftPost(series timeseries.TimeSeries, params ...interface{}) (ti
 	if interval == 0 {
 		return series, nil
 	}
-	if shiftForward == true {
+	if shiftForward {
 		interval = -interval
 	}
 

pkg/datasource/resource_handler.go

@@ -2,11 +2,13 @@ package datasource
 
 import (
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"time"
 
 	"github.com/alexanderzobnin/grafana-zabbix/pkg/zabbix"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/resource/httpadapter"
 )
 
@@ -17,7 +19,11 @@ import (
 func (ds *ZabbixDatasource) RootHandler(rw http.ResponseWriter, req *http.Request) {
 	ds.logger.Debug("Received resource call", "url", req.URL.String(), "method", req.Method)
 
-	rw.Write([]byte("Hello from Zabbix data source!"))
+	_, err := rw.Write([]byte("Hello from Zabbix data source!"))
+	if err != nil {
+		ds.logger.Warn("Error writing response")
+	}
+
 	rw.WriteHeader(http.StatusOK)
 }
 
@@ -26,7 +32,7 @@ func (ds *ZabbixDatasource) ZabbixAPIHandler(rw http.ResponseWriter, req *http.R
 		return
 	}
 
-	body, err := ioutil.ReadAll(req.Body)
+	body, err := io.ReadAll(req.Body)
 	defer req.Body.Close()
 	if err != nil || len(body) == 0 {
 		writeError(rw, http.StatusBadRequest, err)
@@ -67,7 +73,7 @@ func (ds *ZabbixDatasource) DBConnectionPostProcessingHandler(rw http.ResponseWr
 		return
 	}
 
-	body, err := ioutil.ReadAll(req.Body)
+	body, err := io.ReadAll(req.Body)
 	defer req.Body.Close()
 	if err != nil || len(body) == 0 {
 		writeError(rw, http.StatusBadRequest, err)
@@ -95,6 +101,9 @@ func (ds *ZabbixDatasource) DBConnectionPostProcessingHandler(rw http.ResponseWr
 	reqData.Query.TimeRange.To = time.Unix(reqData.TimeRange.To, 0)
 
 	frames, err := dsInstance.applyDataProcessing(req.Context(), &reqData.Query, reqData.Series, true)
+	if err != nil {
+		writeError(rw, http.StatusInternalServerError, err)
+	}
 
 	resultJson, err := json.Marshal(frames)
 	if err != nil {
@@ -103,7 +112,11 @@ func (ds *ZabbixDatasource) DBConnectionPostProcessingHandler(rw http.ResponseWr
 
 	rw.Header().Add("Content-Type", "application/json")
 	rw.WriteHeader(http.StatusOK)
-	rw.Write(resultJson)
+
+	_, err = rw.Write(resultJson)
+	if err != nil {
+		ds.logger.Warn("Error writing response")
+	}
 
 }
 
@@ -115,7 +128,11 @@ func writeResponse(rw http.ResponseWriter, result *ZabbixAPIResourceResponse) {
 
 	rw.Header().Add("Content-Type", "application/json")
 	rw.WriteHeader(http.StatusOK)
-	rw.Write(resultJson)
+
+	_, err = rw.Write(resultJson)
+	if err != nil {
+		log.DefaultLogger.Warn("Error writing response")
+	}
 }
 
 func writeError(rw http.ResponseWriter, statusCode int, err error) {
@@ -132,5 +149,9 @@ func writeError(rw http.ResponseWriter, statusCode int, err error) {
 
 	rw.Header().Add("Content-Type", "application/json")
 	rw.WriteHeader(http.StatusInternalServerError)
-	rw.Write(b)
+
+	_, err = rw.Write(b)
+	if err != nil {
+		log.DefaultLogger.Warn("Error writing response")
+	}
 }

pkg/datasource/zabbix.go

@@ -56,6 +56,10 @@ func (ds *ZabbixDatasourceInstance) queryNumericItems(ctx context.Context, query
 	var items []*zabbix.Item
 	var err error
 	zabbixVersion, err := ds.zabbix.GetVersion(ctx)
+	if err != nil {
+		ds.logger.Warn("Error getting Zabbix version")
+	}
+
 	if zabbixVersion >= 54 {
 		items, err = ds.zabbix.GetItems(ctx, groupFilter, hostFilter, itemTagFilter, itemFilter, "num", showDisabled)
 	} else {

pkg/datasource/zabbix_test.go

@@ -8,8 +8,6 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/backend/log"
 )
 
-var emptyParams = map[string]interface{}{}
-
 var basicDatasourceInfo = &backend.DataSourceInstanceSettings{
 	ID:       1,
 	Name:     "TestDatasource",
@@ -17,13 +15,6 @@ var basicDatasourceInfo = &backend.DataSourceInstanceSettings{
 	JSONData: []byte(`{"username":"username", "password":"password", "cacheTTL":"10m", "authType":"token"}`),
 }
 
-func mockZabbixQuery(method string, params zabbix.ZabbixAPIParams) *zabbix.ZabbixAPIRequest {
-	return &zabbix.ZabbixAPIRequest{
-		Method: method,
-		Params: params,
-	}
-}
-
 func MockZabbixDataSource(body string, statusCode int) *ZabbixDatasourceInstance {
 	zabbixSettings, _ := settings.ReadZabbixSettings(basicDatasourceInfo)
 	zabbixClient, _ := zabbix.MockZabbixClient(basicDatasourceInfo, body, statusCode)