I am trying to apply the predicate not only to the entity parent but also to the child collection. The following is part of my code:
var predicate = PredicateBuilder.New<Entity>();
foreach (string keyword in keywords)
{
string temp = keyword;
predicate = predicate.Or(p => p.Name.Equals(temp));
predicate = predicate.Or(p => p.Addresses.Select(x=> x.Name.Equals(temp));
}
The line predicate = predicate.Or(p => p.Addresses.Select(x=> x.Name.Equals(temp)); is not working ? any ideas as to why?
EDIT
In the following demo I am asking to get entity parent and child with name = tom but I also get child name = tom2.
private static void Main(string[] args)
{
var result = GetAll(GetAll(), new List<string> { "tom" });
}
private static List<User> GetAll()
{
return new List<User>
{
new User
{
Id = 1,
Name = "tom",
Addesses = new List<Addesses>
{
new Addesses { Id = 1, Name = "tom" },
new Addesses { Id = 1, Name = "tom2" },
}
},
new User
{
Id = 1,
Name = "sam",
Addesses = new List<Addesses>
{
new Addesses { Id = 1, Name = "sam" },
new Addesses { Id = 1, Name = "sam2" },
}
},
};
}
private static List<User> GetAll(List<User> users, List<string> keywords)
{
var predicate = PredicateBuilder.New<User>();
foreach (string keyword in keywords)
{
string temp = keyword;
predicate = predicate.Or(p => p.Name.Equals(temp));
predicate = predicate.Or(p => p.Addesses.Any(x => x.Name.Equals(temp)));
}
var result = users
.Where(predicate)
.ToList();
return result;
}
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public List<Addesses> Addesses { get; set; }
}
public class Addesses
{
public int Id { get; set; }
public string Name { get; set; }
}
The call to p.Addresses.Select(x=> x.Name.Equals(temp) is not returning a boolean result.
Depending on your actual logic you may want to look into Any:
predicate = predicate.Or(p => p.Addresses.Any(x=> x.Name.Equals(temp));
or All:
predicate = predicate.Or(p => p.Addresses.All(x=> x.Name.Equals(temp));
Related
The best way I can describe what I'm trying to do is "Nested DistinctBy".
Let's say I have a collection of objects. Each object contains a collection of nicknames.
class Person
{
public string Name { get; set; }
public int Priority { get; set; }
public string[] Nicknames { get; set; }
}
public class Program
{
public static void Main()
{
var People = new List<Person>
{
new Person { Name = "Steve", Priority = 4, Nicknames = new string[] { "Stevo", "Lefty", "Slim" }},
new Person { Name = "Karen", Priority = 6, Nicknames = new string[] { "Kary", "Birdie", "Snookie" }},
new Person { Name = "Molly", Priority = 3, Nicknames = new string[] { "Mol", "Lefty", "Dixie" }},
new Person { Name = "Greg", Priority = 5, Nicknames = new string[] { "G-man", "Chubs", "Skippy" }}
};
}
}
I want to select all Persons but make sure nobody selected shares a nickname with another. Molly and Steve both share the nickname 'Lefty' so I want to filter one of them out. Only the one with highest priority should be included. If there is a highest priority tie between 2 or more then just pick the first one of them. So in this example I would want an IEnumerable of all people except Steve.
EDIT: Here's another example using music album instead of person, might make more sense.
class Album
{
string Name {get; set;}
int Priority {get;set;}
string[] Aliases {get; set;}
{
class Program
{
var NeilYoungAlbums = new List<Album>
{
new Person{ Name = "Harvest (Remastered)", Priority = 4, Aliases = new string[] { "Harvest (1972)", "Harvest (2012)"}},
new Person{ Name = "On The Beach", Priority = 6, Aliases = new string[] { "The Beach Album", "On The Beach (1974)"}},
new Person{ Name = "Harvest", Priority = 3, Aliases = new string[] { "Harvest (1972)"}},
new Person{ Name = "Freedom", Priority = 5, Aliases = new string[] { "Freedom (1989)"}}
};
}
The idea here is we want to show his discography but we want to skip quasi-duplicates.
I would solve this using a custom IEqualityComparer<T>:
class Person
{
public string Name { get; set; }
public int Priority { get; set; }
public string[] Nicknames { get; set; }
}
class PersonEqualityComparer : IEqualityComparer<Person>
{
public bool Equals(Person x, Person y)
{
if (x == null || y == null) return false;
return x.Nicknames.Any(i => y.Nicknames.Any(j => i == j));
}
// This is bad for performance, but if performance is not a
// concern, it allows for more readability of the LINQ below
// However you should check the Edit, if you want a truely
// LINQ only solution, without a wonky implementation of GetHashCode
public int GetHashCode(Person obj) => 0;
}
// ...
var people = new List<Person>
{
new Person { Name = "Steve", Priority = 4, Nicknames = new[] { "Stevo", "Lefty", "Slim" } },
new Person { Name = "Karen", Priority = 6, Nicknames = new[] { "Kary", "Birdie", "Snookie" } },
new Person { Name = "Molly", Priority = 3, Nicknames = new[] { "Mol", "Lefty", "Dixie" } },
new Person { Name = "Greg", Priority = 5, Nicknames = new[] { "G-man", "Chubs", "Skippy" } }
};
var distinctPeople = people.OrderBy(i => i.Priority).Distinct(new PersonEqualityComparer());
EDIT:
Just for completeness, this could be a possible LINQ only approach:
var personNicknames = people.SelectMany(person => person.Nicknames
.Select(nickname => new { person, nickname }));
var groupedPersonNicknames = personNicknames.GroupBy(i => i.nickname);
var duplicatePeople = groupedPersonNicknames.SelectMany(i =>
i.OrderBy(j => j.person.Priority)
.Skip(1).Select(j => j.person)
);
var distinctPeople = people.Except(duplicatePeople);
A LINQ-only solution
var dupeQuery = people
.SelectMany( p => p.Nicknames.Select( n => new { Nickname = n, Person = p } ) )
.ToLookup( e => e.Nickname, e => e.Person )
.SelectMany( e => e.OrderBy( p => p.Priority ).Skip( 1 ) );
var result = people.Except( dupeQuery ).ToList();
See .net fiddle sample
This works once, then you have to clear the set. Or store the results in a collection.
var uniqueNicknames = new HashSet<string>();
IEnumerable<Person> uniquePeople = people
.OrderBy(T => T.Priority) // ByDescending?
.Where(T => T.Nicknames.All(N => !uniqueNicknames.Contains(N)))
.Where(T => T.Nicknames.All(N => uniqueNicknames.Add(N)));
I have the next mongo document structure :
_id
-countryCode
-keywordID
-name
-displayName
-categories:[Array]
-_id
-name
-position
-canonical
I would like to get all the keywords that are in a specific category only knowing the category's ID. I am using the mongo C# driver but don't know how could I check what's inside that array.
I would like to send a list with the category ID's and get back all the keywords that have a category from that list.
public async Task<List<Keyword>> GetKeywords(List<long> keywordCatIds, string countryCode)
{
var mongoCollection = MongoDatabase.GetCollection<Keyword>("Keywords");
try
{
FilterDefinition<Keyword> mongoFilter = Builders<Keyword>.Filter.In(c=>c.Categories, keywordCatIds);
return await mongoCollection.Find(mongoFilter,null).ToListAsync<Keyword>();
}
catch (Exception ex)
{
Logger.Error(ex, "Multiple ids for Country Code: {0}, ids: {1}", countryCode, string.Join(',', keywordCatIds.Select(s => s)));
return null;
}
}
Your In function looks like a "categories._id" filter in normal mongoDB. Which transitions into an ElemMatch. I created a project which fills the db, than selects
all the keywords that are in a specific category only knowing the category's ID
public class CustomID
{
public string CountryCode { get; set; }
public long KeywordId { get; set; }
public string Name { get; set; }
}
public class Keyword
{
[BsonId]
public CustomID Id { get; set; }
public List<Category> Categories { get; set; }
}
public class Category
{
[BsonId]
public long Id { get; set; }
public string Name { get; set; }
public int Position { get; set; }
}
internal class Program
{
public static IMongoDatabase MongoDatabase { get; private set; }
public static async Task Main()
{
var conventionPack = new ConventionPack
{
new CamelCaseElementNameConvention()
};
ConventionRegistry.Register(
"CustomConventionPack",
conventionPack,
t => true);
var client = new MongoClient();
MongoDatabase = client.GetDatabase("SO");
var ret = await GetKeywords(new List<long> {1L, 2L}, "HU-hu");
// ret is A and B. C is filtered out because no category id of 1L or 2L, D is not HU-hu
}
public static async Task<List<Keyword>> GetKeywords(List<long> keywordCatIds, string countryCode)
{
var mongoCollection = MongoDatabase.GetCollection<Keyword>("keywords");
// be ware! removes all elements. For debug purposes uncomment>
//await mongoCollection.DeleteManyAsync(FilterDefinition<Keyword>.Empty);
await mongoCollection.InsertManyAsync(new[]
{
new Keyword
{
Categories = new List<Category>
{
new Category {Id = 1L, Name = "CatA", Position = 1},
new Category {Id = 3L, Name = "CatC", Position = 3}
},
Id = new CustomID
{
CountryCode = "HU-hu",
KeywordId = 1,
Name = "A"
}
},
new Keyword
{
Categories = new List<Category>
{
new Category {Id = 2L, Name = "CatB", Position = 2}
},
Id = new CustomID
{
CountryCode = "HU-hu",
KeywordId = 2,
Name = "B"
}
},
new Keyword
{
Categories = new List<Category>
{
new Category {Id = 3L, Name = "CatB", Position = 2}
},
Id = new CustomID
{
CountryCode = "HU-hu",
KeywordId = 3,
Name = "C"
}
},
new Keyword
{
Categories = new List<Category>
{
new Category {Id = 1L, Name = "CatA", Position = 1}
},
Id = new CustomID
{
CountryCode = "EN-en",
KeywordId = 1,
Name = "EN-A"
}
}
});
var keywordFilter = Builders<Keyword>.Filter;
var categoryFilter = Builders<Category>.Filter;
var mongoFilter =
keywordFilter.ElemMatch(k => k.Categories, categoryFilter.In(c => c.Id, keywordCatIds)) &
keywordFilter.Eq(k => k.Id.CountryCode, countryCode);
return await mongoCollection.Find(mongoFilter).ToListAsync();
}
}
I am working on code which will give Cartesian product of two anonymous types. These 2 anonymous types are generated from database.
Code for 1st anonymous type:
private IEnumerable<object> GetItem()
{
return _unitOfWork.GetRepository<Item>()
.ListAll()
.Select(x => new
{
itemId = x.Id,
itemName = x.Name
})
}
Code for 2nd anonymous type:
private IEnumerable<object> GetVenue()
{
return _unitOfWork.GetRepository<Venue>()
.ListAll()
.Select(x => new
{
locationName = x.Address.City,
venueId = x.VenueId,
venueName = x.Name
})
}
I have following method to get the data and perform Cartesian product and return the data.
public object GetRestrictLookupInfo(IEnumerable<int> lookupCombinations)
{
IEnumerable<object> restrictList = new List<object>();
if (lookupCombinations.Contains(1))
{
var tempProductProfileList = GetItem();
restrictList = tempProductProfileList.AsEnumerable();
}
if (lookupCombinations.Contains(2))
{
var tempProductGroupList = GetVenue();
restrictList = (from a in restrictList.AsEnumerable()
from b in tempProductGroupList.AsEnumerable()
select new { a, b });
}
return restrictList;
}
I have controller which calls this method and return data in json format.
Controller Code
public HttpResponseMessage GetData(IEnumerable<int> lookupCombinations)
{
var lookupRestrictInfo = _sellerService.GetRestrictLookupInfo(lookupCombinations);
return Request.CreateResponse(HttpStatusCode.OK, lookupRestrictInfo);
}
Response expected is:-
[ {
"itemId": 1,
"itemName": "Music",
"locationName": "Paris",
"venueId": 99,
"venueName": "Royal Festival Hall"
} ]
Response which I receive is
[ {
"a": {
"itemId": 1,
"itemName": "Music"
},
"b": {
"locationName": "Paris",
"venueId": 99,
"venueName": "Royal Festival Hall" } }]
I am not able to get the expected JSON string.
You should start with the simplest possible code that shows your problem; your code above has a lot of complexities that may (or may not) have anything to do with your problem. Is this about manipulating anonymous types? Doing a Cartesian product with LINQ? Converting an object to JSON?
Here's one possible answer to what you might be looking for; notice that you can pass around anonymous types using generics instead of object.
namespace AnonymousTypes
{
class Program
{
static string Serialize(object o)
{
var d = (dynamic)o;
return d.ItemId.ToString() + d.ItemName + d.VenueId.ToString() + d.LocationName + d.VenueName;
}
static string GetData<T>(IEnumerable<T> result)
{
var retval = new StringBuilder();
foreach (var r in result)
retval.Append(Serialize(r));
return retval.ToString();
}
static string GetRestrictLookupInfo()
{
var restrictList = new[] { new { Id = 1, Name = "Music" }, new { Id = 2, Name = "TV" } };
var tempProductGroupList = new[] { new { LocationName = "Paris", Id = 99, Name = "Royal Festival Hall" } };
var result = from item in restrictList
from venue in tempProductGroupList
select new
{
ItemId = item.Id,
ItemName = item.Name,
LocationName = venue.LocationName,
VenueId = venue.Id,
VenueName = venue.Name
};
return GetData(result);
}
public static string GetData()
{
return GetRestrictLookupInfo();
}
static void Main(string[] args)
{
var result = GetData();
}
}
}
If that's not what you're looking for, you might start with code that doesn't use anonymous types, such as
namespace AnonymousTypes
{
sealed class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
sealed class Venue
{
public string LocationName { get; set; }
public int Id { get; set; }
public string Name { get; set; }
}
sealed class ItemAndVenue
{
public int ItemId { get; set; }
public string ItemName { get; set; }
public string LocationName { get; set; }
public int VenueId { get; set; }
public string VenueName { get; set; }
}
class Program
{
static IEnumerable<Item> GetItem()
{
return new[] { new Item { Id = 1, Name = "Music" } };
}
static IEnumerable<Venue> GetVenue()
{
return new[] { new Venue { LocationName = "Paris", Id = 99, Name = "Royal Festival Hall" } };
}
static IEnumerable<ItemAndVenue> GetRestrictLookupInfo()
{
var restrictList = GetItem();
var tempProductGroupList = GetVenue();
var result = from item in restrictList
from venue in tempProductGroupList
select new ItemAndVenue
{
ItemId = item.Id,
ItemName = item.Name,
LocationName = venue.LocationName,
VenueId = venue.Id,
VenueName = venue.Name
};
return result;
}
static string GetData()
{
var v = GetRestrictLookupInfo().First();
return v.ItemId.ToString() + v.ItemName + v.VenueId.ToString() + v.LocationName + v.VenueName;
}
static void Main(string[] args)
{
var result = GetData();
}
}
}
In order to produce a single item in the output you need to create a new type, named or anonymous. Since you are using objects rather than actual types, the quickest approach is to cast them to dynamic:
var tempProductGroupList = GetVenue();
restrictList = (from a in restrictList.Cast<dynamic>()
from b in tempProductGroupList.Cast<dynamic>()
select new {
itemId = (int)a.itemId,
itemName = (string)a.itemName,
locationName = (string)b.locationName,
venueId = (int)b.venueId,
venueName = (string)b.venueName
});
This code is tightly coupled to the code producing both lists, because it assumes the knowledge of the field names of types passed into it dynamically. Any change in the structure of source data must be followed by a change in the code making combinations. In addition, it defeats run-time checking, so you need to be very careful with this code.
Try to create a simple object instead of nesting:
select new { a.itemId, a.itemName, b.locationName }
Like an option:
public object GetRestrictLookupInfo(IEnumerable<int> lookupCombinations)
{
List<Dictionary<string, object>> result = new List<Dictionary<string, object>>();
if (lookupCombinations.Contains(1))
{
var tmp = _unitOfWork.GetRepository<Item>()
.ListAll()
.Select(x => new
{
itemId = x.Id,
itemName = x.Name
})
.Select(x =>
{
var dic = new Dictionary<string, object>();
dic.Add(nameof(x.itemId), x.itemId);
dic.Add(nameof(x.itemName), x.itemName);
return dic;
});
result.AddRange(tmp);
}
if (lookupCombinations.Contains(2))
{
var tmp = _unitOfWork.GetRepository<Venue>()
.ListAll()
.Select(x => new
{
locationName = x.Address.City,
venueId = x.VenueId,
venueName = x.Name
})
.Select(x =>
{
var dic = new Dictionary<string, object>();
dic.Add(nameof(x.locationName), x.locationName);
dic.Add(nameof(x.venueId), x.venueId);
dic.Add(nameof(x.venueName), x.venueName);
return dic;
});
result = result.SelectMany(r => tmp.Select(t => r.Concat(t)));
}
return result;
}
It looks like some magic. I uses dictionary instead of object. It can be make in more clear way (extract few methods), but the idea should be clear.
Then, during serialization it will be presented as you need.
It seems that the expected behavior of FirstOrDefault is to complete after finding an item that matches the predicate and the expected behavior of concat is to evaluate lazily. However, the following example enumerates the entire collection even though the predicate matches the first item.
(Thanks for the friendlier code Shlomo)
void Main()
{
var entities = Observable.Defer(() => GetObservable().Concat());
Entity result = null;
var first = entities.FirstOrDefaultAsync(i => i.RowId == 1).Subscribe(i => result = i);
result.Dump();
buildCalled.Dump();
}
// Define other methods and classes here
public IEnumerable<IObservable<Entity>> GetObservable()
{
var rows = new List<EntityTableRow>
{
new EntityTableRow { Id = 1, StringVal = "One"},
new EntityTableRow { Id = 2, StringVal = "Two"},
};
return rows.Select(i => Observable.Return(BuildEntity(i)));
}
public int buildCalled = 0;
public Entity BuildEntity(EntityTableRow entityRow)
{
buildCalled++;
return new Entity { RowId = entityRow.Id, StringVal = entityRow.StringVal };
}
public class Entity
{
public int RowId { get; set; }
public string StringVal { get; set; }
}
public class EntityTableRow
{
public int Id { get; set; }
public string StringVal { get; set; }
}
Is this the expected behavior? Is there a way to defer the enumeration of the objects (specifically the building in this case) until truly needed?
The following is Linqpad-friendly code equivalent to what you have:
void Main()
{
var entities = Observable.Defer(() => GetObservable().Concat());
Entity result = null;
var first = entities.FirstOrDefaultAsync(i => i.RowId == 1).Subscribe(i => result = i);
result.Dump();
buildCalled.Dump();
}
// Define other methods and classes here
public IEnumerable<IObservable<Entity>> GetObservable()
{
var rows = new List<EntityTableRow>
{
new EntityTableRow { Id = 1, StringVal = "One"},
new EntityTableRow { Id = 2, StringVal = "Two"},
};
return rows.Select(i => Observable.Return(BuildEntity(i)));
}
public int buildCalled = 0;
public Entity BuildEntity(EntityTableRow entityRow)
{
buildCalled++;
return new Entity { RowId = entityRow.Id, StringVal = entityRow.StringVal };
}
public class Entity
{
public int RowId { get; set; }
public string StringVal { get; set; }
}
public class EntityTableRow
{
public int Id { get; set; }
public string StringVal { get; set; }
}
If you change GetObservable to the following, you'll get the desired result:
public IObservable<IObservable<Entity>> GetObservable()
{
var rows = new List<EntityTableRow>
{
new EntityTableRow { Id = 1, StringVal = "One"},
new EntityTableRow { Id = 2, StringVal = "Two"},
};
return rows.ToObservable().Select(i => Observable.Return(BuildEntity(i)));
}
It appears the implementation of Concat<TSource>(IEnumerable<IObservable<TSource>>) is eager in evaluating the enumerable, whereas the implementation of Concat<TSource>(IObservable<IObservable<TSource>>) and ToObservable<TSource>(IEnumerable<TSource>) maintain laziness appropriately. I can't say I know why.
I have a list with multiple columns. I want to filter the list based on the requested column name (column name will come as a parameter) with distinct values.
IList<obj1> objTemp= new List<obj1>();
for (int i = 0; i < 15; i++)
{
obj1 temp= new obj1();
temp.Name = "Name" + i;
temp.Age= "Age" + i;
temp.Company= "Company" + i;
objTemp.Add(temp);
}
var distinctTypeIDs = objTemp.Select(x => x.**{my requested column}**).Distinct();
You can use reflection for getting desired property by it's name:
var distinctTypeIDs = objTemp.Select(x => x.GetType().GetProperty("requested_column").GetValue(x))
.Distinct();
I've always been a fan of "mapping" a column to an anonymous method responsible for retrieving the contents of that column:
using System;
using System.Collections.Generic;
using System.Linq;
public class Program
{
public static void Main()
{
Console.WriteLine("Hello World");
var items = new List<SomeObject> {new SomeObject { Age = 10, Name = "Daniel", Company = "InCycle" },
{new SomeObject { Age = 20, Name = "Not Daniel", Company = "Not InCycle" }
}};
var result = Filter<int>(items, "Age");
Console.WriteLine(result.Last());
}
public static IEnumerable<T> Filter<T>(IEnumerable<SomeObject> items, string filterCriteria)
{
var mappings = new Dictionary<string, Func<IEnumerable<SomeObject>, IEnumerable<T>>>
{
{ "Age", filterItems => filterItems.Select(item => item.Age).Distinct().Cast<T>() },
{ "Name", filterItems => filterItems.Select(item => item.Name).Distinct().Cast<T>() },
{ "Company", filterItems => filterItems.Select(item => item.Company).Distinct().Cast<T>() }
};
return mappings[filterCriteria](items);
}
}
public class SomeObject
{
public int Age {get;set;}
public string Name {get;set;}
public string Company {get; set;}
}
The downside to this approach is that if you add additional properties, you could forget to add them to the filtering. Expressions are a solid approach as well.
One way is to use a method like this.
private IList<obj1> SortListAccordingToParameter(string filter)
{
if(filter == "Name")
return objTemp.Select(x => x.Name).Distinct();
else if(filter == "Age")
return objTemp.Select(x => x.Age).Distinct();
else if(filter == "Company")
return objTemp.Select(x => x.Company).Distinct();
}
If you know the type of the property you will be searching for, you could use expressions.
string propName = "Age";
var paramExpression = Expression.Parameter(typeof(Obj1));
// o =>
var memberExpression = Expression.Property(paramExpression, propName);
// o => o.Age
var lambdaExpression = Expression.Lambda<Func<Obj1, string>>(memberExpression, paramExpression);
// (o => o.Age)
var compiled = lambdaExpression.Compile();
IList<Obj1> objTemp = new List<Obj1>();
for (var i = 0; i < 15; i++) {
Obj1 temp = new Obj1();
temp.Name = "Name" + i;
temp.Age = "Age" + i;
temp.Company = "Company" + i;
objTemp.Add(temp);
}
var results = objTemp.Select(compiled);
// equivalent to objTemp.Select(o => o.Age), plus a delegate call and the time to
// compile the lambda.
I would probably wrap this up in a static class, like this:
static class Gen<TModel, TProp> {
public static Func<TModel, TProp> SelectorExpr(string propertyName) {
var pExpr = Expression.Parameter(typeof (TModel));
var mExpr = Expression.Property(pExpr, propertyName);
var lExpr = Expression.Lambda<Func<TModel, TProp>>(mExpr, pExpr);
return lExpr.Compile();
}
}
that way you can write your selector like:
var results = objTemp.Select(Gen<Obj1, string>.SelectorExpr(propName));
That seems a bit more clear to me what it is I'm doing, especially if I'm reading expression DOM code I wrote 6 months after.
public class Test
{
public string name { get; set; }
public string age { get; set; }
public string contact { get; set; }
public Test getName(string name)
{
List<Test> testList = new List<Test>();
testList.Add(new Test { name = "Developer", age = "24", contact = "99009900990" });
testList.Add(new Test { name = "Tester", age = "30", contact = "009900990099" });
return testList.Where(c => c.name == name).FirstOrDefault();
}
}
static void Main(string[] args)
{
Test testObj = new Test();
Test selectedObj = testObj.getName("Developer");
}