Better naming in Tuple classes than "Item1", "Item2"
C#C# 4.0TuplesC# Problem Overview
Is there a way to use a Tuple class, but supply the names of the items in it?
For example:
public Tuple<int, int, int int> GetOrderRelatedIds()
That returns the ids for OrderGroupId, OrderTypeId, OrderSubTypeId and OrderRequirementId.
It would be nice to let the users of my method know which is which. (When you call the method, the results are result.Item1, result.Item2, result.Item3, result.Item4. It is not clear which one is which.)
(I know I could just create a class to hold all these Ids, but it these Ids already have their own classes they live in and making a class for this one method's return value seems silly.)
C# Solutions
Solution 1 - C#
In C# 7.0 (Visual Studio 2017) there is a new construction to do that:
(string first, string middle, string last) LookupName(long id)
Solution 2 - C#
Up to C# 7.0, there was no way to do this short of defining your own type.
Solution 3 - C#
Here is an overly complicated version of what you are asking:
class MyTuple : Tuple<int, int>
{
public MyTuple(int one, int two)
:base(one, two)
{
}
public int OrderGroupId { get{ return this.Item1; } }
public int OrderTypeId { get{ return this.Item2; } }
}
Why not just make a class?
Solution 4 - C#
Reproducing my answer from this post as it is a better fit here.
Starting C# v7.0, it is now possible to name the tuple properties which earlier used to default to names like Item1, Item2 and so on.
Naming the properties of Tuple Literals:
var myDetails = (MyName: "Foo", MyAge: 22, MyFavoriteFood: "Bar");
Console.WriteLine($"Name - {myDetails.MyName}, Age - {myDetails.MyAge}, Passion - {myDetails.MyFavoriteFood}");
The output on console:
Name - Foo, Age - 22, Passion - Bar
Returning Tuple (having named properties) from a method:
static void Main(string[] args)
{
var empInfo = GetEmpInfo();
Console.WriteLine($"Employee Details: {empInfo.firstName}, {empInfo.lastName}, {empInfo.computerName}, {empInfo.Salary}");
}
static (string firstName, string lastName, string computerName, int Salary) GetEmpInfo()
{
//This is hardcoded just for the demonstration. Ideally this data might be coming from some DB or web service call
return ("Foo", "Bar", "Foo-PC", 1000);
}
The output on console:
Employee Details: Foo, Bar, Foo-PC, 1000
Creating a list of Tuples having named properties
var tupleList = new List<(int Index, string Name)>
{
(1, "cow"),
(5, "chickens"),
(1, "airplane")
};
foreach (var tuple in tupleList)
Console.WriteLine($"{tuple.Index} - {tuple.Name}");
Output on console:
1 - cow
5 - chickens
1 - airplane
Note: Code snippets in this post are using string interpolation feature of C# v6 as detailed here.
Solution 5 - C#
With .net 4 you could perhaps look at the ExpandoObject, however, don't use it for this simple case as what would have been compile-time errors become run-time errors.
class Program
{
static void Main(string[] args)
{
dynamic employee, manager;
employee = new ExpandoObject();
employee.Name = "John Smith";
employee.Age = 33;
manager = new ExpandoObject();
manager.Name = "Allison Brown";
manager.Age = 42;
manager.TeamSize = 10;
WritePerson(manager);
WritePerson(employee);
}
private static void WritePerson(dynamic person)
{
Console.WriteLine("{0} is {1} years old.",
person.Name, person.Age);
// The following statement causes an exception
// if you pass the employee object.
// Console.WriteLine("Manages {0} people", person.TeamSize);
}
}
// This code example produces the following output:
// John Smith is 33 years old.
// Allison Brown is 42 years old.
Something else worth mentioning is an anonymous type for within a method, but you need to create a class if you want to return it.
var MyStuff = new
{
PropertyName1 = 10,
PropertyName2 = "string data",
PropertyName3 = new ComplexType()
};
Solution 6 - C#
TL:DR -> System.ValueTuples can have custom names for fields, System.Tuples cannot.
Just to clarify, there are 2 different types of tuples in C# 7.0 and later.
System.Tuple and System.ValueTuple
When you declare a tuple via the Tuple<...> class:
public Tuple<int, string, int> GetUserInfo();
You're declaring a Tuple object data type.
When you declare a tuple via parenthesis:
public (int id, string name, int age) GetUserInfo();
You're declaring a ValueTuple value data type.
Each one functions and behaves differently. In your question, your method returns a System.Tuple object.
Unfortunately, Tuple objects created via the System.Tuple class have no built in functionality to give each property a custom name. They always default to ItemN depending on how many properties they contain.
System.ValueTuple values on the other hand can contain custom named fields.
For more info, you can refer to Tuple types (C# reference) and/or the links to each class above. But essentially some of the key differences of the 2 different types of tuples that the documentation highlights are:
> C# tuples, which are backed by System.ValueTuple types, are different
> from tuples that are represented by System.Tuple types. The main
> differences are as follows:
>
> - System.ValueTuple types are value types. System.Tuple types are reference types.
> - System.ValueTuple types are mutable. System.Tuple types are immutable.
> - Data members of System.ValueTuple types are fields. Data members of System.Tuple types are properties.
So if your method needs to return a System.Tuple object or you desire the behavior of that type of object more, then as of writing this, you can't achieve what you want. However, if your method can return a System.ValueTuple value, then you can give it custom named fields in the returned value.
Solution 7 - C#
MichaelMocko Answered is great,
but I want to add a few things which I had to figure out
(string first, string middle, string last) LookupName(long id)
above Line will give you compile-time error if you are using .net framework < 4.7
So if you have a project that is using .net framework < 4.7 and still you want to use ValueTuple than workAround would be installing this NuGet package
Update:
Example of returning Named tuple from a method and using it
public static (string extension, string fileName) GetFile()
{
return ("png", "test");
}
Using it
var (extension, fileName) = GetFile();
Console.WriteLine(extension);
Console.WriteLine(fileName);
Solution 8 - C#
As of today, it's this simple. Instead of using the Tuple keyword
public Tuple<int, int, int int> GetOrderRelatedIds()
Use this.
public (int alpha, int beta, int candor) GetOrderRelatedIds()
Get the values like this.
var a = GetOrderRelatedIds();
var c = a.alpha;
Solution 9 - C#
No, you can't name the tuple members.
The in-between would be to use ExpandoObject instead of Tuple.
Solution 10 - C#
If the types of your items are all different, here is a class I made to get them more intuitively.
The usage of this class:
var t = TypedTuple.Create("hello", 1, new MyClass());
var s = t.Get<string>();
var i = t.Get<int>();
var c = t.Get<MyClass>();
Source code:
public static class TypedTuple
{
public static TypedTuple<T1> Create<T1>(T1 t1)
{
return new TypedTuple<T1>(t1);
}
public static TypedTuple<T1, T2> Create<T1, T2>(T1 t1, T2 t2)
{
return new TypedTuple<T1, T2>(t1, t2);
}
public static TypedTuple<T1, T2, T3> Create<T1, T2, T3>(T1 t1, T2 t2, T3 t3)
{
return new TypedTuple<T1, T2, T3>(t1, t2, t3);
}
public static TypedTuple<T1, T2, T3, T4> Create<T1, T2, T3, T4>(T1 t1, T2 t2, T3 t3, T4 t4)
{
return new TypedTuple<T1, T2, T3, T4>(t1, t2, t3, t4);
}
public static TypedTuple<T1, T2, T3, T4, T5> Create<T1, T2, T3, T4, T5>(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5)
{
return new TypedTuple<T1, T2, T3, T4, T5>(t1, t2, t3, t4, t5);
}
public static TypedTuple<T1, T2, T3, T4, T5, T6> Create<T1, T2, T3, T4, T5, T6>(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6)
{
return new TypedTuple<T1, T2, T3, T4, T5, T6>(t1, t2, t3, t4, t5, t6);
}
public static TypedTuple<T1, T2, T3, T4, T5, T6, T7> Create<T1, T2, T3, T4, T5, T6, T7>(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7)
{
return new TypedTuple<T1, T2, T3, T4, T5, T6, T7>(t1, t2, t3, t4, t5, t6, t7);
}
public static TypedTuple<T1, T2, T3, T4, T5, T6, T7, T8> Create<T1, T2, T3, T4, T5, T6, T7, T8>(T1 t1, T2 t2, T3 t3, T4 t4, T5 t5, T6 t6, T7 t7, T8 t8)
{
return new TypedTuple<T1, T2, T3, T4, T5, T6, T7, T8>(t1, t2, t3, t4, t5, t6, t7, t8);
}
}
public class TypedTuple<T>
{
protected Dictionary<Type, object> items = new Dictionary<Type, object>();
public TypedTuple(T item1)
{
Item1 = item1;
}
public TSource Get<TSource>()
{
object value;
if (this.items.TryGetValue(typeof(TSource), out value))
{
return (TSource)value;
}
else
return default(TSource);
}
private T item1;
public T Item1 { get { return this.item1; } set { this.item1 = value; this.items[typeof(T)] = value; } }
}
public class TypedTuple<T1, T2> : TypedTuple<T1>
{
public TypedTuple(T1 item1, T2 item2)
: base(item1)
{
Item2 = item2;
}
private T2 item2;
public T2 Item2 { get { return this.item2; } set { this.item2 = value; this.items[typeof(T2)] = value; } }
}
public class TypedTuple<T1, T2, T3> : TypedTuple<T1, T2>
{
public TypedTuple(T1 item1, T2 item2, T3 item3)
: base(item1, item2)
{
Item3 = item3;
}
private T3 item3;
public T3 Item3 { get { return this.item3; } set { this.item3 = value; this.items[typeof(T3)] = value; } }
}
public class TypedTuple<T1, T2, T3, T4> : TypedTuple<T1, T2, T3>
{
public TypedTuple(T1 item1, T2 item2, T3 item3, T4 item4)
: base(item1, item2, item3)
{
Item4 = item4;
}
private T4 item4;
public T4 Item4 { get { return this.item4; } set { this.item4 = value; this.items[typeof(T4)] = value; } }
}
public class TypedTuple<T1, T2, T3, T4, T5> : TypedTuple<T1, T2, T3, T4>
{
public TypedTuple(T1 item1, T2 item2, T3 item3, T4 item4, T5 item5)
: base(item1, item2, item3, item4)
{
Item5 = item5;
}
private T5 item5;
public T5 Item5 { get { return this.item5; } set { this.item5 = value; this.items[typeof(T5)] = value; } }
}
public class TypedTuple<T1, T2, T3, T4, T5, T6> : TypedTuple<T1, T2, T3, T4, T5>
{
public TypedTuple(T1 item1, T2 item2, T3 item3, T4 item4, T5 item5, T6 item6)
: base(item1, item2, item3, item4, item5)
{
Item6 = item6;
}
private T6 item6;
public T6 Item6 { get { return this.item6; } set { this.item6 = value; this.items[typeof(T6)] = value; } }
}
public class TypedTuple<T1, T2, T3, T4, T5, T6, T7> : TypedTuple<T1, T2, T3, T4, T5, T6>
{
public TypedTuple(T1 item1, T2 item2, T3 item3, T4 item4, T5 item5, T6 item6, T7 item7)
: base(item1, item2, item3, item4, item5, item6)
{
Item7 = item7;
}
private T7 item7;
public T7 Item7 { get { return this.item7; } set { this.item7 = value; this.items[typeof(T7)] = value; } }
}
public class TypedTuple<T1, T2, T3, T4, T5, T6, T7, T8> : TypedTuple<T1, T2, T3, T4, T5, T6, T7>
{
public TypedTuple(T1 item1, T2 item2, T3 item3, T4 item4, T5 item5, T6 item6, T7 item7, T8 item8)
: base(item1, item2, item3, item4, item5, item6, item7)
{
Item8 = item8;
}
private T8 item8;
public T8 Item8 { get { return this.item8; } set { this.item8 = value; this.items[typeof(T8)] = value; } }
}
Solution 11 - C#
Just to add to @MichaelMocko answer. Tuples have couple of gotchas at the moment:
You can't use them in EF expression trees
Example:
public static (string name, string surname) GetPersonName(this PersonContext ctx, int id)
{
return ctx.Persons
.Where(person => person.Id == id)
// Selecting as Tuple
.Select(person => (person.Name, person.Surname))
.First();
}
This will fail to compile with "An expression tree may not contain a tuple literal" error. Unfortunately, the expression trees API wasn't expanded with support for tuples when these were added to the language.
Track (and upvote) this issue for the updates: https://github.com/dotnet/roslyn/issues/12897
To get around the problem, you can cast it to anonymous type first and then convert the value to tuple:
// Will work
public static (string name, string surname) GetPersonName(this PersonContext ctx, int id)
{
return ctx.Persons
.Where(person => person.Id == id)
.Select(person => new { person.Name, person.Surname })
.ToList()
.Select(person => (person.Name, person.Surname))
.First();
}
Another option is to use ValueTuple.Create:
// Will work
public static (string name, string surname) GetPersonName(this PersonContext ctx, int id)
{
return ctx.Persons
.Where(person => person.Id == id)
.Select(person => ValueTuple.Create(person.Name, person.Surname))
.First();
}
References:
-
https://www.damirscorner.com/blog/posts/20181207-NoSupportForTuplesInExpressionTrees.html
-
https://stackoverflow.com/questions/43400071/convert-anonymous-type-to-new-c-sharp-7-tuple-type
You can't deconstruct them in lambdas
There's a proposal to add the support: https://github.com/dotnet/csharplang/issues/258
Example:
public static IQueryable<(string name, string surname)> GetPersonName(this PersonContext ctx, int id)
{
return ctx.Persons
.Where(person => person.Id == id)
.Select(person => ValueTuple.Create(person.Name, person.Surname));
}
// This won't work
ctx.GetPersonName(id).Select((name, surname) => { return name + surname; })
// But this will
ctx.GetPersonName(id).Select(t => { return t.name + t.surname; })
References:
They won't serialize nicely
using System;
using Newtonsoft.Json;
public class Program
{
public static void Main() {
var me = (age: 21, favoriteFood: "Custard");
string json = JsonConvert.SerializeObject(me);
// Will output {"Item1":21,"Item2":"Custard"}
Console.WriteLine(json);
}
}
Tuple field names are only available at compile time and are completely wiped out at runtime.
References:
Solution 12 - C#
This is very annoying and I expect future versions of C# will address this need. I find the easiest work around to be either use a different data structure type or rename the "items" for your sanity and for the sanity of others reading your code.
Tuple<ApiResource, JSendResponseStatus> result = await SendApiRequest();
ApiResource apiResource = result.Item1;
JSendResponseStatus jSendStatus = result.Item2;
Solution 13 - C#
(double, int) t1 = (4.5, 3);
Console.WriteLine($"Tuple with elements {t1.Item1} and {t1.Item2}.");
// Output:
// Tuple with elements 4.5 and 3.
(double Sum, int Count) t2 = (4.5, 3);
Console.WriteLine($"Sum of {t2.Count} elements is {t2.Sum}.");
// Output:
// Sum of 3 elements is 4.5.
From Docs: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/value-tuples
Solution 14 - C#
I think I would create a class but another alternative is output parameters.
public void GetOrderRelatedIds(out int OrderGroupId, out int OrderTypeId, out int OrderSubTypeId, out int OrderRequirementId)
Since your Tuple only contains integers you could represent it with a Dictionary<string,int>
var orderIds = new Dictionary<string, int> {
{"OrderGroupId", 1},
{"OrderTypeId", 2},
{"OrderSubTypeId", 3},
{"OrderRequirementId", 4}.
};
but I don't recommend that either.
Solution 15 - C#
Why is everyone making life so hard. Tuples are for rather temporary data processing. Working with Tuples all the time will make the code very hard to understand at some point. Creating classes for everything could eventually bloat your project.
It's about balance, however...
Your problem seems to be something you would want a class for. And just for the sake of completeness, this class below also contains constructors.
This is the proper pattern for
- A custom data type
- with no further functionality. Getters and setters can also be expanded with code, getting/setting private members with the name pattern of "_orderGroupId", while also executing functional code.
- Including constructors. You can also choose to include just one constructor if all properties are mandatory.
- If you want to use all constructors, bubbling like this is the proper pattern to avoid duplicate code.
public class OrderRelatedIds
{
public int OrderGroupId { get; set; }
public int OrderTypeId { get; set; }
public int OrderSubTypeId { get; set; }
public int OrderRequirementId { get; set; }
public OrderRelatedIds()
{
}
public OrderRelatedIds(int orderGroupId)
: this()
{
OrderGroupId = orderGroupId;
}
public OrderRelatedIds(int orderGroupId, int orderTypeId)
: this(orderGroupId)
{
OrderTypeId = orderTypeId;
}
public OrderRelatedIds(int orderGroupId, int orderTypeId, int orderSubTypeId)
: this(orderGroupId, orderTypeId)
{
OrderSubTypeId = orderSubTypeId;
}
public OrderRelatedIds(int orderGroupId, int orderTypeId, int orderSubTypeId, int orderRequirementId)
: this(orderGroupId, orderTypeId, orderSubTypeId)
{
OrderRequirementId = orderRequirementId;
}
}
Or, if you want it really simple: You can also use type initializers:
OrderRelatedIds orders = new OrderRelatedIds
{
OrderGroupId = 1,
OrderTypeId = 2,
OrderSubTypeId = 3,
OrderRequirementId = 4
};
public class OrderRelatedIds
{
public int OrderGroupId;
public int OrderTypeId;
public int OrderSubTypeId;
public int OrderRequirementId;
}
Solution 16 - C#
I would write the Item names in the summay.. so by hovering over the function helloworld() the text will say hello = Item1 and world = Item2
helloworld("Hi1,Hi2");
/// <summary>
/// Return hello = Item1 and world Item2
/// </summary>
/// <param name="input">string to split</param>
/// <returns></returns>
private static Tuple<bool, bool> helloworld(string input)
{
bool hello = false;
bool world = false;
foreach (var hw in input.Split(','))
{
switch (hw)
{
case "Hi1":
hello= true;
break;
case "Hi2":
world= true;
break;
}
}
return new Tuple<bool, bool>(hello, world);
}
Solution 17 - C#
You Can write a class that contains the Tuple.
You need to override the Equals and GetHashCode functions
and the == and != operators.
class Program
{
public class MyTuple
{
private Tuple<int, int> t;
public MyTuple(int a, int b)
{
t = new Tuple<int, int>(a, b);
}
public int A
{
get
{
return t.Item1;
}
}
public int B
{
get
{
return t.Item2;
}
}
public override bool Equals(object obj)
{
return t.Equals(((MyTuple)obj).t);
}
public override int GetHashCode()
{
return t.GetHashCode();
}
public static bool operator ==(MyTuple m1, MyTuple m2)
{
return m1.Equals(m2);
}
public static bool operator !=(MyTuple m1, MyTuple m2)
{
return !m1.Equals(m2);
}
}
static void Main(string[] args)
{
var v1 = new MyTuple(1, 2);
var v2 = new MyTuple(1, 2);
Console.WriteLine(v1 == v2);
Dictionary<MyTuple, int> d = new Dictionary<MyTuple, int>();
d.Add(v1, 1);
Console.WriteLine(d.ContainsKey(v2));
}
}
will return:
True
True
Solution 18 - C#
C# 7 tuple example
var tuple = TupleExample(key, value);
private (string key1, long value1) ValidateAPIKeyOwnerId(string key, string value)
{
return (key, value);
}
if (!string.IsNullOrEmpty(tuple.key1) && tuple.value1 > 0)
{
//your code
}