hashtable keys from multiple objects in linq - c#

Hashtable mainhash = new Hashtable();
testdata td = new testdata() { value = "td" };
td.hash.Add("1", "tdvalue1");
td.hash.Add("2", "tdvalue2");
td.hash.Add("3", "tdvalue3");
td.hash.Add("4", "tdvalue4");
td.hash.Add("5", "tdvalue5");
testdata td1 = new testdata() { value = "td1" };
td1.hash.Add("1", "td1value1");
td1.hash.Add("2", "td1value2");
td1.hash.Add("3", "td1value3");
td1.hash.Add("4", "td1value4");
td1.hash.Add("5", "td1value5");
testdata td2 = new testdata() { value = "td2" };
td2.hash.Add("1", "td2value1");
td2.hash.Add("2", "td2value2");
td2.hash.Add("3", "td2value3");
td2.hash.Add("4", "td2value4");
td2.hash.Add("5", "td2value5");
testdata td3 = new testdata() { value = "td3" };
td3.hash.Add("1", "td3value1");
td3.hash.Add("2", "td3value2");
td3.hash.Add("3", "td3value3");
td3.hash.Add("4", "td3value4");
td3.hash.Add("5", "td3value5");
testdata td4 = new testdata() { value = "td4" };
td4.hash.Add("1", "td4value1");
td4.hash.Add("2", "td4value2");
td4.hash.Add("3", "td4value3");
td4.hash.Add("4", "td4value4");
td4.hash.Add("5", "td4value5");
mainhash.Add(1, td);
mainhash.Add(2, td1);
mainhash.Add(3, td2);
mainhash.Add(4, td3);
mainhash.Add(5, td4);
how to select all the keys using SelectMany by Linq into one list??
what i need to do in this??
var values = mainhash.Values.Cast<testdata>().Select(x => x.hash)
.SelectMany(x=> x.Keys);
what is wrong in this??

It doesn't know the type to use from Hashtable.Keys.
Try:
var values = mainhash.Values.Cast<testdata>().Select(x => x.hash)
.SelectMany(x => x.Keys.Cast<string>());
But better: use Dictionary<TKey,TValue> instead of Hashtable.

try below query -
var values = mainhash.Values.Cast<testdata>().SelectMany(x => x.hash.Keys.Cast<string>());
But, use dictionary instead of hashtable. It actually reduce the overhead of casting the objects.
hope above code helps you !!

Related

c# Nest and Elasticsearch Aggregations

Does anyone know how to do multiple aggregations with nest?
I have found quite a few examples unfortunately none of them work.
Here's what I have:
Vehicles fields = new Vehicles();
//create a terms query
var query = new TermsQuery
{
IsVerbatim = true,
Field = "VehicleOwnerId",
Terms = new string[] { 25 },
};
var aggregations = new Dictionary<string, IAggregationContainer>
{
{ "years", new AggregationContainer
{
Terms = new TermsAggregation(nameof(fields.Year))
{
Field = new Field(nameof(fields.Year))
}
}
}
//,
//{ "makes", new AggregationContainer
// {
// Terms = new TermsAggregation("Make")
// {
// Field = new Field(nameof(fields.Make))
// }
// }
//}
};
//create the search request
var searchRequest = new SearchRequest
{
Query = query,
From = 0,
Size = 100,
Aggregations = aggregations
};
var result = client.SearchAsync<InventoryLiveView>(searchRequest).Result;
var years = result.Aggregations.Terms("years");
Dictionary<string, long> yearCounts = new Dictionary<string, long>();
foreach (var item in years.Buckets)
{
yearCounts.Add(item.Key, item.DocCount ?? 0);
}
If I just execute the code like this it works. Years returns the aggregates as expected. If I try to add another field (like the one commented out above) it fails and I get zero records.
How can I get multiple aggregates in one query? I see examples of it all over, but none of the examples I've tried seem to work and most seem to be outdated (including some in the Nest documentation).
I have also tried this approach which is pretty close to the documentation.
//create the search request
var searchRequest = new SearchRequest
{
Query = query,
From = 0,
Size = 100,
//Aggregations = aggregations
Aggregations = new AggregationDictionary
{
{
"childAgg", new ChildrenAggregation("childAgg", typeof(Vehicles ))
{
Aggregations = new AggregationDictionary
{
{"years", new TermsAggregation(nameof(fields.VehicleYear))},
{"makes", new TermsAggregation(nameof(fields.VehicleMakeName))},
{"models", new TermsAggregation(nameof(fields.VehicleModelName))},
}
}
}
}
};
var result = client.SearchAsync<Vehicles>(searchRequest).Result;
This just produces a null reference exception.
I guess I'll never have too worry about getting to proud as a programmer :)
It's too often that the solution to the problem makes me feel stupid when it reveals itself.
So my issue was that the field I was trying to use in the aggregation was text and couldn't be used. I switched everything to the ID fields and multiple aggregations work as expected.
So this version of the code works like a champ:
Vehicle fields = new Vehicle ();
//create a terms query
var query = new TermsQuery
{
IsVerbatim = true,
Field = "VehicleOwnerId",
Terms = new string[] { "30" },
};
string[] Fields = new[]
{
nameof(fields.Year),
nameof(fields.MakeId),
nameof(fields.ModelId)
};
var aggregations = new Dictionary<string, IAggregationContainer>();
foreach (string sField in Fields)
{
var termsAggregation = new TermsAggregation(sField)
{
Field = sField
};
aggregations.Add(sField, new AggregationContainer { Terms = termsAggregation });
}
//create the search request
var searchRequest = new SearchRequest
{
Query = query,
From = 0,
Size = 10,
Aggregations = aggregations
};
var result = client.SearchAsync<InventoryLiveView>(searchRequest).Result;
var years = result.Aggregations.Terms(nameof(fields.Year));
Dictionary<string, long> yearCounts = new Dictionary<string, long>();
foreach (var item in years.Buckets)
{
yearCounts.Add(item.Key, item.DocCount ?? 0);
}
The exact error from elasticsearch, which I saw using postman was:
Fielddata is disabled on text fields by default. Set fielddata=true on [MakeName] in order to load fielddata in memory by uninverting the inverted index. Note that this can however use significant memory. Alternatively use a keyword field instead.
Here is my example using SearchDescriptors. My only problem is how to serialize returned results into a proper Key Value list. Is Looping through a fields list the best way to return results.
SearchDescriptor<Advert> agghDescriptor = new SearchDescriptor<Advert>();
agghDescriptor.Aggregations(ag => ag.Terms("make", a => a.Field(f => f.Make)) &&
ag.Terms("region", a => a.Field(f => f.Region)) &&
ag.Terms("city", a => a.Field(f => f.City)) &&
ag.Terms("category", a => a.Field(f => f.Category)) &&
ag.Terms("application", a => a.Field(f => f.Application)) &&
ag.Terms("portalId", a => a.Field(f => f.PortalId)) &&
ag.Terms("isActiveAuctionAdvert", a => a.Field(f => f.IsActiveAuctionAdvert)) &&
ag.Terms("isBargainAccount", a => a.Field(f => f.IsBargainAccount)) &&
ag.Terms("condition", a => a.Field(f => f.Condition))
);
agghDescriptor.Size(0);
var json2 = _client.RequestResponseSerializer.SerializeToString(agghDescriptor);
var aggregationResult = _client.Search<Advert>(agghDescriptor);
List<string> fields = new List<string>();
fields.Add("make");
fields.Add("category");
fields.Add("region");
List<Aggregation> aggregations = new List<Aggregation>();
foreach (var field in fields)
{
var aggrs = aggregationResult.Aggregations.Terms(field);
List<AggregateItem> aggregateItems = new List<AggregateItem>();
foreach (var item in aggrs.Buckets)
{
aggregateItems.Add(new AggregateItem()
{
Count = item.DocCount ?? 0,
Key = item.Key
});
}
aggregations.Add(new Aggregation()
{
Name = field,
Aggregates = aggregateItems
});
}

Append items to an object

I have created a Linq statement to get a list of items from the database. So I need to loop trough the query and append to object to then serialize to then be able to use as json in javascript. The problem is I cannot append to the declared object 'obj'. Can anyone help??
DataContext dataContext = new DataContext();
var query = from qr in dataContext.tblStocks
where qr.enable == true
select qr;
var obj = new JObject();
foreach (var item in query)
{
//obj = new JObject();
obj = ( new JObject(
new JProperty("stockID",item.stockID),
new JProperty("itemDepartmentID", item.itemDepartmentID),
new JProperty("item" , item.item),
new JProperty("description", item.description),
new JProperty("stockAmount", item.stockAmount),
new JProperty("priceExlVat", item.priceExlVat),
new JProperty("vat", item.vat),
new JProperty("priceIncVAT", item.priceIncVAT),
new JProperty("upc1", item.upc1),
new JProperty("upc2", item.upc2)
));
}
var serialized = JsonConvert.SerializeObject(obj);
return serialized;
You are reassigning obj each time through the loop hence all other data will be lost.
Easier to create an array:
obj = new JArray();
foreach (var item in query) {
obj.Add(new JObject(
new JProperty(...),
...));
}
Why don't you just serialize your object?
List<dynamic> obj = new List<dynamic>();
foreach(var item in query) {
obj.Add(new
{
itemDepartmentID = item.itemDepartmentID,
description = item.description,
...
});
}
var serialized = JsonConvert.SerializeObject(obj);
Alternative you could use an anonymous type in the query and just serialize the entire query for the query returns an IEnumerable<T> and this is converted automatically to an jsonArray:
DataContext dataContext = new DataContext();
var query = dataContext.tblStocks
.Where(stockItem => stockItem.enable)
.Select(stockItem => new
{
stockItem.stockID,
stockItem.itemDepartmentID,
stockItem.item,
stockItem.description,
stockItem.stockAmount,
stockItem.priceExlVat,
stockItem.vat,
stockItem.priceIncVat,
stockItem.upc1,
stockItem.upc2
});
return JsonConvert.SerializeObject(query);

Add items to list from IEnumerable using LinQ

I'm adding new items to a list from a IEnumerable (query.Roles).
var query = GetRoles();
var vm = new CreateUserViewModel();
vm.Role = new List<CreateUserViewModel.Item>();
foreach (var Role in query.Roles)
{
vm.Role.Add(new CreateUserViewModel.Item
{
Label = Role.Label,
RoleNumber = Role.RoleNumer
});
}
How i can do the 'Add' to the list with Linq?
AddRange should do it for you:
vm.Role.AddRange(query.Roles.Select(r => new CreateUserViewModel.Item
{
Label = r.Label,
RoleNumber = r.RoleNumer
}));
AddRange takes an IEnumerable parameter and adds each item to the collection.
vm.Role = query
.Roles
.Select(r=>new CreatUserViewModel
.Item{Label = r.Label,
RoleNumber = r.RoleNumber})
.ToList();

DataTable select help

I am trying to convert datatable to List. Could you please help me with the query?
var result = DataTable1.AsEnumerable().Select(e => {e.Field<int>("MID"), e.Field<string>("MTX")}).ToList();
JavaScriptSerializer ser = new JavaScriptSerializer();
string json = ser.Serialize(result);
Thank you..
You need to provide names for the properties inside your Select call. These names will not automatically and unambiguously resolve in this particular case. Try
var result = DataTable1.AsEnumerable().Select(row => new { Mid = row.Field<int>("Mid"), MTX = row.Field<string>("MTX") });
JavaScriptSerializer serializer = new JavaScriptSerializer();
string json = serializer.Serialize(result);
Those names will then become part of the json result. Such as
[{"Mid":1,"MTX":"A"},{"Mid":2,"MTX":"B"}]
IEnumerable<DataRow> sequence = dt.AsEnumerable();
or
List<DataRow> list = dt.AsEnumerable().ToList();
Try:
var result = DataTable1.AsEnumerable()
.Select(e => new object[] { e.Field<int>("MID"), e.Field<string>("MTX") })
.ToList();

Can we make this more terse with linq?

I am curious if there is a way where I can capture the lower lines (the creation of the dictionary and loop to add values) in the linq statement itself. Right now the select new returns a new anonymous type but I am wondering if there is a way to make it return a Dictionary with all the values pre-populated.
XDocument reader = XDocument.Load("sl.config");
var configValues = from s in reader.Descendants("add") select new { Key = s.Attribute("key").Value, s.Attribute("value").Value };
Dictionary<string, string> Settings = new Dictionary<string, string>();
foreach (var s in configValues)
{
Settings.Add(s.Key, s.Value);
}
Try Enumerable.ToDictionary extension method.
XDocument reader = XDocument.Load("sl.config");
var Settings = reader.Descendants("add")
.ToDictionary(s => s.Attribute("key").Value, s => s.Attribute("value").Value);
var = XDocument.Load("sl.config").Descendants("add").ToDictionary
(x => x.Attribute("key"). Value, x => x.Attribute("value"). Value);

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