Removing an element from an array in MongoDB

Question

I am new to learning how to use MongoDB and am stuck pretty early on, so hoping someone can help me out with a simple example.

I can successfully connect to a Mongo server and create a collection and create objects to put in it. I am doing all of this through c# and the c# driver.

I have the following custom objects defined in my code.

public class Feature
{
    public string FeatureName { get; set; }
    public ObjectId Id { get; set; }
    public List<Scenario> Scenarios { get; set; } 
}

public class Scenario
{
    private string _notes;
    public string ScenarioName { get; set; }
    public List<string> Givens { get; set; }
    public List<string> Whens { get; set; }
    public List<string> Thens { get; set; }
    public string Explanation { get; set; }
    public string Notes { get; set; }
}

As you can see, the Feature object contains a property which is a list of scenarios.

In my Mongo collection I have a Feature object that contains 3 scenarios. What I want to do in C# is write a method that can remove a specific scenario from a feature:

User provides a feature and scenario name to a method
Method checks the feature, looking through the list within it, for a scenario where the scenario.scenarioname matches the scenario name passed in to the method
If it exists, then remove the scenario from the feature and update Mongo and return a bool of true. If it doesn't exist return false

I am sure that this is probably going to be obvious when I see an example, but I have tried and get stuck trying to work through the List property looking for a property on a sub object.

I hope that all makes sense??!?

Thanks in advance.

P

IF you have answered your question you should submit it as an answer to this question. If you then have follow-on questions, you should ask them as separate questions and link back to this for background, if necessary. You should not edit your question with a different question. — Nick Udell
– Nick Udell, Commented Jun 12, 2014 at 13:17
I reverted your edit. Please post the answer you found as an answer to this question. Answering your own question isn't frowned upon on stackexchange - it is even encouraged (you get a badge for it). When someone has a better answer, they will likely post it. When your answer can be improved, people will likely comment on it and suggest improvements. — Philipp
– Philipp, Commented Jun 12, 2014 at 14:32

Codesharper · Accepted Answer · 2014-06-12 20:06:12Z

2

Resolved it myself...

public bool DeleteScenario(string featureName, string scenarioName)
    {
        var collection = GetCollection<Feature>();
        var query = Query.EQ("FeatureName", featureName);
        var resultingFeature = collection.Find(query).SetLimit(1).FirstOrDefault();

        if (resultingFeature == null)
        {
            return false;
        }

        // we have found our feature and it exists.

        foreach (var scenario in resultingFeature.Scenarios)
        {
            if (scenario.ScenarioName == scenarioName)
            {
                resultingFeature.Scenarios.Remove(scenario);
                collection.Save(resultingFeature);
                return true;
            }
        }

        return true;

    }

answered Jun 12, 2014 at 20:06

Codesharper

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