Make a query from a string in mongodb, python3

Question

I am trying to make query in mongodb where I don't know how many variables I have from the beginning. You get an array with variables(strings) and then mongo should return via the $or operator so there are no duplicates.

def findRecipes(IngredientsHome):
#Query and return all the alternatives

arrayCompleteSearch = [];
if len(IngredientsHome) > 1:
    #theHardStuuff
    #Create the query based on ingredientsarray
    argsCount = len(IngredientsHome)
    argsFunction = "";
    for i in range(0, len(IngredientsHome)):
        if i < (len(IngredientsHome)-1):
            argsFunction += ("{"+'"_Ingredients":' + '"' + IngredientsHome[i] + '"' "}, ")
        else:
            argsFunction += "{" + '"_Ingredients":' + '"' + IngredientsHome[i] + '"' + "}"

if I then do like this

print("coll.find({" + '$or' + ':' + '[' + argsFunction + ']' "})")

the commandline will print(not execute) the command i want to do in mongodb but I don't know how to make it work in mongo and return the results to an array. I am using pymongo and there i don't if it's possible to use a string as a full query. In sql I could put the whole "query" as a string "SELECT * FROM ..." while pymongo need : outside the string, more like coll.find({"String":"String"}). Is there a similar method or another way to make this query when I don't know how many expressions I have from the beginning in my mongodb query?

Are you trying to get the string in return or do you have to perform actual MongoDB query? — errata
– errata, Commented May 31, 2017 at 11:58
I have to do a MongoDB query. I need results from the database. — NotUser9123
– NotUser9123, Commented May 31, 2017 at 12:15

errata · Accepted Answer · 2017-05-31 13:10:39Z

1

Instead of constructing your query as a string, use PyMongo methods to query your database, for example:

coll.find({'_Ingredients': IngredientsHome[i]})

or you can pass the Python list and use $in in your query:

coll.find({'_Ingredients': {'$in': IngredientsHome}})

Read more about how to use PyMongo here.

edited May 31, 2017 at 13:10

answered May 31, 2017 at 12:18

errata

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2 Comments

NotUser9123 Over a year ago

Yes but the problem is that I don't know how many parameters I have from the beginning. I don't know if i should ma a query on IngredientsHome[1], IngredientsHome[2] and IngredientsHome[3] or just 2 IngredientsHome. If i just loop and make a new query everytime I will end up with multiples duplicates. 1 recipe contains multiples ingredients so the same recipe will come up multiple times.

errata Over a year ago

@NotUser9123 Updated my answer!

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