Added decorator to test availability of datasets

Used decorator tool to validate dataset exists on views

ref-test/app/admin/views.py

@@ -2,7 +2,7 @@ from ..forms.admin import AddTimeAdjustment, CreateTest, CreateUser, DeleteUser,
 from ..models import Dataset, Entry, Test, User
 from ..tools.auth import disable_if_logged_in, require_account_creation
 from ..tools.forms import get_dataset_choices, get_time_options, send_errors_to_client
-from ..tools.data import check_is_json, validate_json
+from ..tools.data import check_dataset_exists, check_is_json, validate_json
 from ..tools.test import  answer_options, get_correct_answers
 
 from flask import abort, Blueprint, jsonify, render_template, redirect, request, send_file, session
@@ -247,15 +247,12 @@ def _download(id:str):
 @admin.route('/tests/<string:filter>/', methods=['GET'])
 @admin.route('/tests/', methods=['GET'])
 @login_required
+@check_dataset_exists
 def _tests(filter:str=None):
-    datasets = Dataset.query.all()
     tests = None
     _tests = Test.query.all()
     form = None
     now = datetime.now()
-    if not datasets:
-        flash('There are no available question datasets. Please upload a question dataset in order to set up an exam.', 'error')
-        return redirect(url_for('admin._questions'))
     if filter not in ['create','active','scheduled','expired','all']: return redirect(url_for('admin._tests', filter='active'))
     if filter == 'create':
         form = CreateTest()

ref-test/app/editor/views.py

@@ -1,6 +1,7 @@
 from ..forms.admin import EditDataset
 from ..models import Dataset, User
 from ..tools.forms import get_dataset_choices, send_errors_to_client
+from ..tools.data import check_dataset_exists
 
 from flask import Blueprint, flash, jsonify, redirect, render_template, request
 from flask.helpers import url_for
@@ -27,6 +28,7 @@ def _editor():
     return render_template('/editor/index.html', form=form)
 
 @editor.route('/<string:id>/')
+@check_dataset_exists
 @login_required
 def _editor_console(id:str=None):
     dataset = Dataset.query.filter_by(id=id).first()

ref-test/app/tools/data.py

@@ -1,8 +1,13 @@
+from ..models import Dataset
+
 from flask import current_app as app
+from flask import flash, redirect
+from flask.helpers import url_for
 
 import json
 from pathlib import Path
 from random import shuffle
+from functools import wraps
 
 def load(filename:str):
     data_dir = Path(app.config.get('DATA'))
@@ -67,3 +72,13 @@ def get_tag_list(dataset:list):
         if block['type'] == 'block':
             for question in block['questions']: output = list(set(output) | set(question['tags']))
     return output
+
+def check_dataset_exists(function):
+    @wraps(function)
+    def wrapper(*args, **kwargs):
+        datasets = Dataset.query.all()
+        if not datasets:
+            flash('There are no available question datasets. Please upload a question dataset first, or use the question editor to create a new dataset.', 'error')
+            return redirect(url_for('admin._questions'))
+        return function(*args, **kwargs)
+    return wrapper