LINQ filter by attribute nested in 3 lists

Question

I am kind of new to working with LINQ and ran into a problem which I can't seem to solve.

So I basically need to filter on an attribute of an object that is nested inside three lists. The Data (as a JSON) looks as follows:

  [
   {
      "userName":"John",
      "resourceTypeUserVms":[
         {
            "name":"Administration",
            "description":null,
            "resourceUserVms":[
               {
                  "policyUserVm":{
                     "policyName":"admin",
                     "priority":0,
                     "metaHash":"abc123",
                     "policySetName":"Admin",
                     "policySetDescription":""
                  },
                  "accessType":"Administration",
                  "accessDescription":null,
                  "metaData":"{\"Name\":\"Admin\"}"
               },
               {
                  "policyUserVm":{
                     "policyName":"test",
                     "priority":0,
                     "metaHash":"abc123",
                     "policySetName":"Test",
                     "policySetDescription":""
                  },
                  "accessType":"Administration",
                  "accessDescription":null,
                  "metaData":"{\"Name\":\"test123\"}"
               }
            ]
         },
         {
            "name":"Database",
            "description":null,
            "resourceUserVms":[
               {
                  "policyUserVm":{
                     "policyName":"read_x",
                     "priority":0,
                     "metaHash":"def456",
                     "policySetName":"Test",
                     "policySetDescription":""
                  },
                  "accessType":"read",
                  "accessDescription":null,
                  "metaData":"{\"Server\":\"srv\",\"Name\":\"test\"}"
               }
            ]
         },
         {
            "name":"Configuration",
            "description":null,
            "resourceUserVms":[
               {
                  "policyUserVm":{
                     "policyName":"readc",
                     "priority":0,
                     "metaHash":"ghi789",
                     "policySetName":"Configurations",
                     "policySetDescription":""
                  },
                  "accessType":"read",
                  "accessDescription":null,
                  "metaData":"{\"Name\":\"ServiceName\"}"
               }
            ]
         }
      ]
   }
]

So I basically have a User with x amount of ResourceTypesUserVms and those ResourceTypes have x ResourceUserVms.

I need to filter on the attribute "metaData" inside of the ResourceUserVms. So if for example enter "Admin" into the filter bar, I want to get something like this in return:

[
   {
      "userName":"John",
      "resourceTypeUserVms":[
         {
            "name":"Administration",
            "description":null,
            "resourceUserVms":[
               {
                  "policyUserVm":{
                     "policyName":"admin",
                     "priority":0,
                     "metaHash":"abc123",
                     "policySetName":"Admin",
                     "policySetDescription":""
                  },
                  "accessType":"Administration",
                  "accessDescription":null,
                  "metaData":"{\"Name\":\"Admin\"}"
               }
            ]
         }
      ]
   }
]

I have found some solutions online suggesting I do something like this:

filteredUsers = users
        .Where(x => x.ResourceTypeUserVms
        .Any(x => x.ResourceUserVms
        .Any(x => x.MetaData.ToLower().Contains(value))))
        .ToList();

However, this does not yield the result I want.

I got the expected result by doing this (unclean code ahead):

foreach(var user in users)
        {
            foreach(var resourceType in user.ResourceTypeUserVms)
            {
                foreach(var resource in resourceType.ResourceUserVms)
                {
                    if (resource.MetaData.ToLower().Contains(value))
                    {
                        filteredUsersTemp.Add(
                            new UserUserVm
                            {
                                UserName = user.UserName,
                                ResourceTypeUserVms = new List(
                                    new ResourceTypeUserVm[] {
                                        new ResourceTypeUserVm
                                        {
                                            Description = resourceType.Description,
                                            Name = resourceType.Name,
                                            ResourceUserVms = new List(
                                                new ResourceUserVm[]{ resource }
                                                )
                                        }
                                    })
                            }
                            );
                    }
                }
            }
        }

I would really appreciate if someone could help me figure out a nice, clean way of doing this using LINQ!

user_11660685 · Answer

I guess, you need to filter ResourceUserVms by MetaData as well.

So, firstly, get all users that have ResourceTypeUserVms that have ResourceUserVms that have MetaData (==value). You actually did it.

Then you can get rid of MetaData-useless ResourceUserVms.

   filteredUsers = users
            .Where(x => x.ResourceTypeUserVms
            .Any(x => x.ResourceUserVms
            .Any(x => x.MetaData.ToLower().Contains(value))))
            .ToList();

filteredUsers = filteredUsers.Select(x=>{

    x.ResourceTypeUserVms = x.ResourceTypeUserVms.Select(y=> {

       y.ResourceUserVms = y.ResourceUserVms.Where(s=>s.MetaData.ToLower().Contains(value)))).ToList();

       return y;

    }).ToList();

return x;

}).ToList();

user_9922629 · Answer

from user in users
from resourceType in user.ResourceTypeUserVms
from resource in resourceType.ResourceUserVms
where resource.MetaData.ToLower().Trim().Contains(value)

Also, it is recommended to use Any() instead of Contains().

LINQ filter by attribute nested in 3 lists

2 Answers