How Can I Efficiently Use a WHERE IN Clause Equivalent in LINQ?

Where IN Clause in LINQ (Improved Solution)

In SQL, the WHERE IN clause is used to check if a field matches any value from a list. You can achieve a similar functionality in LINQ using the following improved approach.

public List<State> Wherein(string listofcountrycodes)
{
    string[] countryCode = listofcountrycodes.Split(',');
    var states = from states in _objdatasources.StateList()
                 where countryCode.Contains(states.CountryCode)
                 select new State
                 {
                     StateName = states.StateName
                 };
    return states.ToList();
}

This code uses the LINQ Contains method to check if the CountryCode of a state matches any value in the countryCode array. The ToList method is used to convert the states query into a concrete list.

Explanation:

• The from clause defines the range of elements to query, in this case the StateList of the _objdatasources object.
• The where clause filters the results based on the condition countryCode.Contains(states.CountryCode), which checks if the CountryCode of the current state is present in the list of country codes.
• The select clause projects the selected states into a new list of State objects, containing only the StateName property.
• Finally, the ToList method converts the LINQ query into a concrete List object.

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