Find object in list with given property value then find dictionary value

问题

I have a list of objects. Each of these objects has a Name property, and an ObservablePairCollection which is just a custom dictionary that works EXACTLY like a dictionary, has a key/value pair.

Given two strings, one for name and one for key, I want to find the object that first matches the name given, and then selects the pair from that model's dictionary that matches the given key value.

Example: Given the string "model1" for name, and "Latitude" for the key, an object who's name property equals model1 should be found, and then a key/value pair in the object's dictionary should be returned where the key equals Latitude.

Currently I can do the first part to match the Name by using:

private ObservableCollection<ModelBase> models;
//add objects to models

string stringToFind = "model1";

models.Single(m => m.Name == stringToFind);

So, this returns the object who's Name property equals model1.

I'm unable to find the right statement to use to get the key/value pair though.

Here's the relative parts of the class:

private ObservablePairCollection<string, string> _fields = new ObservablePairCollection<string, string>();
public ObservablePairCollection<string, string> Fields
{
    get { return _fields; }
    set { _fields = value; OnPropertyChanged("Fields"); }
}

private string _name;
public string Name
{
    get { return _name; }
    protected set
    {
        if (_name != value)
        {
            _name = value;
            OnPropertyChanged("Name");
        }
    }
}

I'd like to use LINQ if possible, but not a huge deal if not.

回答1:

First of all, why Single? Must there be only one object with the given Name and must you enforce it in this specific code? Bear in mind that Single is expensive because it will enumerate the whole collection to make sure the found object is unique.

If you are just interested in finding the first, if any, then simply use the aptly named First extension method:

models.First(m => m.Name == stringToFind);

Ok, so that returns the first object with a given Name, if any, you simply need to filter the Fields proyerty:

var pair = models.First(m => m.Name == stringToFind)
                ?.Fields
                 .First(f => f.Key = keyToFind);

来源：https://stackoverflow.com/questions/43805309/find-object-in-list-with-given-property-value-then-find-dictionary-value

标签

linq

dictionary