better error handling and slog response

service_a/internal/domains/common.go

@@ -0,0 +1,6 @@
+package domains
+
+var (
+	SQLSTATE_25P02 = "25P02"
+	SQLSTATE_23505 = "23505"
+)

service_a/internal/domains/meteo/handlers.go

@@ -27,20 +27,23 @@ func NewHandler(service *Service) *Handler {
 func (h *Handler) IngestCSV(w http.ResponseWriter, r *http.Request) {
 	err := r.ParseMultipartForm(10 << 20)
 	if err != nil {
-		http.Error(w, ErrParsingForm.Error(), http.StatusBadRequest)
+		slog.Error(ErrParsingForm.Error(), "error", err)
+		h.ToJSON(w, http.StatusBadRequest, app.H{"error": ErrParsingForm})
 		return
 	}
 
 	file, header, err := r.FormFile("file")
 	if err != nil {
-		http.Error(w, ErrRetrievingFile.Error(), http.StatusBadRequest)
+		slog.Error(ErrRetrievingFile.Error(), "error", err)
+		h.ToJSON(w, http.StatusBadRequest, app.H{"error": ErrRetrievingFile})
 		return
 	}
 	defer file.Close()
 
 	content, err := io.ReadAll(file)
 	if err != nil {
-		http.Error(w, ErrReadingFile.Error(), http.StatusInternalServerError)
+		slog.Error(ErrReadingFile.Error(), "error", err)
+		h.ToJSON(w, http.StatusInternalServerError, app.H{"error": ErrReadingFile})
 		return
 	}
 
@@ -57,13 +60,13 @@ func (h *Handler) IngestCSV(w http.ResponseWriter, r *http.Request) {
 		slog.Error(ErrCannotParseFile.Error(),
 			"filename", header.Filename,
 			"error", err)
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		h.ToJSON(w, http.StatusConflict, app.H{"error": err})
 		return
 	}
 	fileStats.ElapsedMS = int(time.Since(start).Milliseconds())
 	h.s.UpdateElapsedMS(r.Context(), fileStats.BatchID, fileStats.ElapsedMS)
 
-	slog.Info("CSV file processed",
+	slog.Info("csv file processed",
 		"filename", header.Filename,
 		"rows_inserted", fileStats.RowsInserted,
 		"rows_rejected", fileStats.RowsRejected,
@@ -79,7 +82,9 @@ func (h *Handler) IngestExcel(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *Handler) GetCities(w http.ResponseWriter, r *http.Request) {
-	h.ToJSON(w, http.StatusOK, app.H{"cities": h.s.GetCities(r.Context())})
+	cities := h.s.GetCities(r.Context())
+	slog.Info("cities retrieved", "count", len(cities))
+	h.ToJSON(w, http.StatusOK, app.H{"cities": cities})
 }
 
 func (h *Handler) GetMeteoData(w http.ResponseWriter, r *http.Request) {
@@ -94,7 +99,7 @@ func (h *Handler) GetMeteoData(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := params.Validate(); err != nil {
-		slog.Error("Error validating struct", "error", err)
+		slog.Error("error validating struct", "error", err)
 		h.ToJSON(w, http.StatusBadRequest, app.H{"error": err.Error()})
 		return
 	}
@@ -106,7 +111,7 @@ func (h *Handler) GetMeteoData(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	slog.Info("Data retrieved", "location", params.Location)
+	slog.Info("data retrieved", "location", params.Location)
 
 	h.ToJSON(w, http.StatusOK, app.H{"meteo_data": meteoData})
 }

service_a/internal/domains/meteo/repository.go

@@ -3,6 +3,8 @@ package meteo
 import (
 	"context"
 	"fmt"
+	"servicea/internal/domains"
+	"strings"
 
 	b "github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
@@ -76,6 +78,9 @@ func (pgx *pgxRepo) insertBatch(ctx context.Context, tx b.Tx, fileChecksum strin
 	var batchID int
 	err := tx.QueryRow(ctx, insertBatch, 0, fileChecksum).Scan(&batchID)
 	if err != nil {
+		if strings.Contains(err.Error(), domains.SQLSTATE_23505) {
+			return 0, ErrRecordAlreadyExists
+		}
 		return 0, fmt.Errorf("error inserting batch: %w", err)
 	}
 	return batchID, nil
@@ -102,6 +107,9 @@ func (pgx *pgxRepo) insertAcceptedMeteoData(ctx context.Context, tx b.Tx, batchI
 		rowsInserted++
 		if err != nil {
 			results.Close()
+			if strings.Contains(err.Error(), domains.SQLSTATE_23505) {
+				return 0, ErrRecordAlreadyExists
+			}
 			return 0, fmt.Errorf("error executing batch command %d: %w", i, err)
 		}
 	}