Deleting multiple items from JSON data in flask form - flask

Question

I have a WTForm that submits its data in JSON format. Say the database is one recipe to many recipe steps.
{
"stepset-0": {
"recipe_step_id": "5",
"recipe_step_name": "step 1",
"recipe_step_temp": "666.0"
},
"stepset-1": {
"recipe_step_id": "6",
"recipe_step_name": "Step 2",
"recipe_step_temp": "57.0"
},
"stepset-2": {
"recipe_step_id": "7",
"recipe_step_name": "Step 3",
"recipe_step_temp": "68.0"
},
"stepset-3": {
"recipe_step_id": "8",
"recipe_step_name": "Step 4",
"recipe_step_temp": "73.0"
}
}
I'm using JS to remove elements from the table, but currently trying to get my head round how to update the data in the recipe_steps table.
The logic should be basically:
Find the steps in the step table that match the recipe.
See if those steps are in the JSON data (match using the id)
Delete anything that isn't in the submitted JSON.
So if I remove the row with recipe_step_id '8', this gets submitted to the route, and the route works out that it isn't in the data, removes it from the db, then processes the rest of the data as per the route.
My current route (showing add/update functions) is thus:
#app.route('/recipe/recipesteps/<int:recipe_id>/update', methods=['GET', 'POST'])
#login_required
def updaterecipesteps(recipe_id):
recipe = Recipe.query.get_or_404(recipe_id)
data = request.form
nested_data = nest_once(data)
for key, val in nested_data.items():
recipe_step_id = val['recipe_step_id']
recipe_step_temp = val['recipe_step_temp']
recipe_step_name = val['recipe_step_name']
recipe_id = recipe
if recipe_step_id:
recipe_step = ReciperecipeSteps.query.get_or_404(recipe_step_id)
recipe_step.name = recipe_step_name
recipe_step.step_temp = recipe_step_temp
db.session.commit()
else:
recipe_step = ReciperecipeSteps(name=recipe_step_name,
step_temp=recipe_step_temp,
recipe_id=recipe_step.recipe_id)
db.session.add(recipe_step)
db.session.commit()
return redirect(url_for('recipe', recipe_id=recipe.id))
The closest I've got to this is this query:
mash_steps = RecipeSteps.query.filter(RecipeSteps.id.not_in([nested_data.recipe_step_id for val in nested_data.items]), RecipeSteps.recipe_id == recipe_id).all()
...but Python won't iterate over the object.

Answer 1

Probably far from the best way of doing this (I'd imagine I could have parsed the JSON data in the query), but this is what I got working:
# Build a list from the step ids
step_id = []
for key, value in nested_data.items():
recipe_step_id = value['recipe_step_id']
step_id.append(recipe_step_id)
# Query matching items that aren't on the list
recipe_steps = RecipeSteps.query.filter(RecipeSteps.id.not_in(step_id), RecipeSteps.recipe_id == recipe.id).all()
# Loop through the results and delete
for m in recipe_steps:
db.session.delete(m)
db.session.commit()