ValueTuple<(string loanID, decimal x, ...)> does not contain a definition for 'loanID' in c#

Question

I am just passing a ValueTuple to a function. I want to process the Values within this ValueTuple.

Unfortunately, VS 2017 only allows me to access credit.Item1. No further Items. So far I had no issues with ValueTuples.

The error in the compiler is:

ValueTuple<(string loanID, decimal y, ...)> does not contain a definition for 'loanID'...

The code is

public void LogCredit(
    ValueTuple<(
        string loanID,
        decimal discount,
        decimal interestRate,
        decimal realReturn,
        decimal term,
        int alreadyPayedMonths)>
    credit)
{
    // not working!
    string loanID = credit.loanID;

    // this is the only thing i can do:
    string loanID = credit.Item1;

    // not working either!
    decimal realReturn = credit.Item2;
}

Meanwhile, when hovering over credit I can see it correctly:

Any Suggestions?

Answer 1

Your parameter has only one single field Item1 because it is not of type ValueTuple<...>, but of type ValueTuple<ValueTuple<...>>: The single type parameter of the outer ValueTuple is another ValueTuple, where this inner C# tuple now contains your string, decimal and int fields. Therefore, in your code you have to write string loanID = credit.Item1.loanID; to access those fields.

In order to access your fields as expected, remove the enclosing ValueTuple, leaving just the C# tuple behind:

public void LogCredit((string loanID, decimal discount, decimal interestRate,
    decimal realReturn, decimal term, int alreadyPayedMonths) credit)
{
    string loanID = credit.loanID;

    decimal realReturn = credit.Item4;
}

To utilize named fields of ValueTuple, I prefer the usage of the C# 7 Tuples.

For the sake of completeness, here is a general blog article and an in-depth blog article about tuples in C# 7.