Linq to return a value based on another value in an object

Question

I have an object as such:

{
  "orderSummaries": [
    {
      "orderTypeId": "8b3206ed-0ea0-41bc-8d4b-b39882f81019",
      "name": "DefaultOrder",
      "description": "default order"
    },
    {
      "orderTypeId": "6ebc76dd-1d0f-4292-84f2-f95b71f821cb",
      "name": "Loan purchase",
      "description": "loan purchase order"
    }
    ]}

I am trying to use a linq query to return the 'orderTypeId' of the order that has a particular name.. but i can't go further

e.g orders.orderSummaries.Select(x => x.Name == request.name)//this will be Loan purchase
// return the order orderTypeId value with the name of the request variable

Not sure how to do this in linq?

Answer 1

You should be using both Where and Select - the first is for filtering the values you need, and the second is for projecting the properties you want to return:

 orders
    .orderSummaries
    .Where(x => x.Name == request.name)
    .Select(x => x.orderTypeId);

Answer 2

I believe this should do.

  var orderTypeId = orders
     .orderSummaries
     .FirstOrDefault(x => x.Name == request.name)?
     .orderTypeId;

if you're sure the Name is unique. otherwise:

 var orderTypeIds = orders
         .orderSummaries
         .Where(x => x.Name == request.name)
         .Select(x => x.orderTypeId);
 

Answer 3

You need to use .Where() instead of .Select() to filter out the list and then .Select() to project only orderTypeId

var result = orders.orderSummaries
     .Where(x => x.Name == request.name)  //Filter orderSummaries based on request.name
     .Select(x => x.orderTypeId); //Project only orderTypeId instead of entire orderSummary object

---

Where() : Filters a sequence of values based on a predicate.

In your case, predicate is x.Name == request.name

Select() : Projects each element of a sequence into a new form.

In your case, new form is IEnumerable of orderTypeId (s) instead of entire entire IEnumerable of orderSummaries .