From 35419644dd9093630649093a4e2fba06c19ffb0c Mon Sep 17 00:00:00 2001
From: Frederick Muriuki Muriithi
Date: Mon, 30 Sep 2024 16:34:34 -0500
Subject: Extract common check into decorator for reusability.

---
 uploader/phenotypes/views.py | 57 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/uploader/phenotypes/views.py b/uploader/phenotypes/views.py
index 4565844..a79e863 100644
--- a/uploader/phenotypes/views.py
+++ b/uploader/phenotypes/views.py
@@ -1,4 +1,6 @@
 """Views handling ('classical') phenotypes."""
+from functools import wraps
+
 from flask import (flash,
                    request,
                    url_for,
@@ -89,19 +91,60 @@ def list_datasets(species: dict, population: dict, **kwargs):# pylint: disable=[
                                activelink="list-datasets")
 
 
+def with_dataset(
+        species_redirect_uri: str,
+        population_redirect_uri: str,
+        redirect_uri: str
+):
+    """Ensure the dataset actually exists."""
+    def __decorator__(func):
+        @wraps(func)
+        @with_population(species_redirect_uri, population_redirect_uri)
+        def __with_dataset__(**kwargs):
+            try:
+                _spcid = int(kwargs["species_id"])
+                _popid = int(kwargs["population_id"])
+                _dsetid = int(kwargs.get("dataset_id"))
+                select_dataset_uri = redirect(url_for(
+                    redirect_uri, species_id=_spcid, population_id=_popid))
+                if not bool(_dsetid):
+                    flash("You need to select a valid 'dataset_id' value.",
+                          "alert-danger")
+                    return select_dataset_uri
+                with database_connection(app.config["SQL_URI"]) as conn:
+                    dataset = dataset_by_id(conn, _spcid, _popid, _dsetid)
+                    if not bool(dataset):
+                        flash("You must select a valid dataset.",
+                              "alert-danger")
+                        return select_dataset_uri
+            except ValueError as _verr:
+                app.logger.debug(
+                    "Exception converting 'dataset_id' to integer: %s",
+                    kwargs.get("dataset_id"),
+                    exc_info=True)
+                flash("Expected 'dataset_id' value to be an integer."
+                      "alert-danger")
+                return select_dataset_uri
+            return func(dataset=dataset, **kwargs)
+        return __with_dataset__
+    return __decorator__
+
+
 @phenotypesbp.route(
     "<int:species_id>/populations/<int:population_id>/phenotypes/datasets"
     "/<int:dataset_id>/view",
     methods=["GET"])
 @require_login
-@with_population(species_redirect_uri="species.populations.phenotypes.index",
-                 redirect_uri="species.populations.phenotypes.select_population")
+@with_dataset(
+    species_redirect_uri="species.populations.phenotypes.index",
+    population_redirect_uri="species.populations.phenotypes.select_population",
+    redirect_uri="species.populations.phenotypes.list_datasets")
 def view_dataset(# pylint: disable=[unused-argument]
-        species: dict, population: dict, dataset_id: int, **kwargs):
+        species: dict, population: dict, dataset: dict, **kwargs):
     """View a specific dataset"""
     with database_connection(app.config["SQL_URI"]) as conn:
         dataset = dataset_by_id(
-            conn, species["SpeciesId"], population["Id"], dataset_id)
+            conn, species["SpeciesId"], population["Id"], dataset["Id"])
         if not bool(dataset):
             flash("Could not find such a phenotype dataset!", "alert-danger")
             return redirect(url_for(
@@ -114,13 +157,13 @@ def view_dataset(# pylint: disable=[unused-argument]
         return render_template("phenotypes/view-dataset.html",
                                species=species,
                                population=population,
-                               dataset={"Id": dataset_id},
+                               dataset=dataset,
                                phenotype_count=phenotypes_count(
-                                   conn, population["Id"], dataset_id),
+                                   conn, population["Id"], dataset["Id"]),
                                phenotypes=enumerate_sequence(
                                    dataset_phenotypes(conn,
                                                       population["Id"],
-                                                      dataset_id,
+                                                      dataset["Id"],
                                                       offset=start_at,
                                                       limit=count),
                                    start=start_at+1),
-- 
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