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

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?

CodePudding user response：

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);

CodePudding user response：

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.

CodePudding user response：

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);