Neet to convert list with sub list into flatt list - LINQ C#

Question

1.00/5 (1 vote)

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I need to flatt list<object> with sub object into 1 list.

i have
List<object1> into this list i have sub list
with properties
class object1
{
public int id;
public int name;
public list<object2> items;
}
class object 2
{
public int id;
public string name;
public decimal price;
}

for example
object 1 have id = 1, name=One with list of 3 items..

i need this in 1 flat list
List<object 3=""> flatt
object 3 will have

class object3
{
public int id;
public int name;
public int itemid;
public string name;
public decimal price;
}

i need this with linq solution. TNX

What I have tried:

class object1
{
    public int id;
    public int name;
    public list<object2> items;
}

class object 2
{
    public int id;
    public string name;
    public decimal price;
}

class object3
{
    public int id;
    public int name;
    public int itemid;
    public string name;
    public decimal price;
}

.....

Posted 28-Jul-19 23:52pm

Member 14068594

Updated 30-Jul-19 4:27am

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Comments

OriginalGriff 29-Jul-19 6:54am

And?
What have you tried?
Where are you stuck?
What help do you need?

BillWoodruff 29-Jul-19 7:45am

The fact the code you show would never compile indicates you have made no effort. Hint: study the Linq 'Select statement.

If you show edited code that actually compiles, I'll assist.

2 solutions

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Gerry Schmitz · Answer 1 · 2019-07-29T06:44:00

Solution 1

C#

var object3Query = object1List
   .Select( o1 => o1.items
      .Select( o2 => new object3(){ 
         id = o1.id, 
         name = o1.name, 
         ...,
         price = o2.price }
));

Posted 29-Jul-19 6:44am

Gerry Schmitz

Comments

Maciej Los 29-Jul-19 13:55pm

5ed!

Benktesh Sharma · Answer 2 · 2019-07-30T04:27:00

I modified your int name field in object1 and object3 to nameid as there will be name collision.

class object1
    {
        public int id;
        public int nameId;
        public List<object2> items;
    }

class object2
{
public int id;
public string name;
public decimal price;
}

class object3
{
    public int id;
    public int nameId;
    public int itemid;
    public string name;
    public decimal price;
}

Some sample data here:

var object2List1 = new List<object2>
            {
                new object2 {id = 1, name = "1", price = 10},
                new object2 {id = 2, name = "2", price = 20},
                new object2 {id = 3, name = "3", price = 30},
            };

            var object2List2 = new List<object2>
            {
                new object2 {id = 11, name = "11", price = 11},
                new object2 {id = 21, name = "21", price = 21},
                new object2 {id = 31, name = "31", price = 31},
            };

            var object1List = new List<object1>
            {
                new object1 {id = 100, nameId = 100, items = object2List1},
                new object1 {id = 110, nameId = 110, items = object2List2},
            };

Final code to build the list of object3 is shown here. Please note the use of SelectMany in the query above.

<pre>
var object3List = object1List
                .SelectMany(o1 =>
                    o1.items.Select(o2 => new object3()
                    {
                        id = o1.id,
                        nameId = o1.nameId,
                        itemid = o2.id,
                        name = o2.name,
                        price = o2.price

                    })).ToList();

foreach (var ol in object3List)
{
   Console.WriteLine(ol.id + "\t" + ol.nameId + "\t" + ol.itemid + "\t" + ol.name + "\t" + ol.price)
};