I have a DB with no constraints (given, not changeable). My model look like
public MyModel
{
public long Id { get; set; }
// Even if database column 'Value' could be NULL,
// the model - from business view - could not.
public long Value { get; set; }
}
My data I'd like to read is
Id Value
1 1
2 2
3 NULL
4 4
When I read with with DBContext.MyModel.ToList() it fails, of course. Is there any possibility to catch the error on 3rd row and return the 3 valid ones?
I don't dependent on EF but I like an automatic mapping between DB an Code.
Update:
It seems I wasn't specific enough. I need the 3 rows AS WELL AS a notification for the error.
Additional I've created a simple case for demo. In real life I have around 800 tables with up to 250 columns. I can't catch anything by model modification like dates out of range, missing relationships and other stuff.
What I really need is a try..catch for every row or an event on row reading failure, something like this.
Ok, solved. Not very elegant, but functional.
var query = _DBContext
.Database
.SqlQuery<MyModel>("SELECT * FROM MyModel");
var result = new List<MyModel>();
var enumerator = query.GetEnumerator();
while (true)
{
try
{
var success = enumerator.MoveNext();
if (!success)
break;
var model = enumerator.Current;
result.Add(model);
}
catch (Exception ex)
{
}
}
return result;
You need to use nullable type
public MyModel
{
public long Id { get; set; }
// Even if database column 'Value' could be NULL,
// the model - from business view - could not.
public long? Value { get; set; }
}
And also, in your select query, you should exlude Value = null
var myModel = models.Where(x => x.Value != null);
Hope it helps.
I'm not entirely sure I understand what you're trying to do, but if you want to get a reflection of what's in the table, then why not make your model match the query? If Value can be NULL, then make Value nullable (i.e. define it as long?).
That way, you can simply do:
var records = DbContext.MyModel.ToList();
If you then want to filter out the NULLs, you can do:
records.Where(r => r.Value.HasValue)
And if you want the ones with NULLs you can do:
records.Where(r => !r.Value.HasValue)
Or if you want to know whether any row had a NULL you could do:
records.Any(r => !r.Value.HasValue)
Use the following code:
var list = from m in DBContext.MyModel
where (m != null)
select m;
And then just convert var list to a List of your choosing.
Edit 1
var myModel = models.Where(x => x.Value != null).ToList();
As kienct89 suggested might also work.
Edit 2
There are multiple options for "catching" the error
If you want to throw an exception just use this:
if(myList.Count() < DBContext.MyModel.Count()){
Exception myException = new Exception("Not all items ware correctly loaded");
throw myException;
}
OR create a seperate array with the faulty ones:
var faultyList = from m in DBContext.MyModel
where (m == null)
select m;
Or:
var faultyList= models.Where(x => x.Value == null).ToList();
Related
i know it is not complicated but i struggle with it.
I have IList<Material> collection
public class Material
{
public string Number { get; set; }
public decimal? Value { get; set; }
}
materials = new List<Material>();
materials.Add(new Material { Number = 111 });
materials.Add(new Material { Number = 222 });
And i have DbSet<Material> collection
with columns Number and ValueColumn
I need to update IList<Material> Value property based on DbSet<Material> collection but with following conditions
Only one query request into database
The returned data from database has to be limited by Number identifier (do not load whole database table into memory)
I tried following (based on my previous question)
Working solution 1, but download whole table into memory (monitored in sql server profiler).
var result = (
from db_m in db.Material
join m in model.Materials
on db_m.Number.ToString() equals m.Number
select new
{
db_m.Number,
db_m.Value
}
).ToList();
model.Materials.ToList().ForEach(m => m.Value= result.SingleOrDefault(db_m => db_m.Number.ToString() == m.Number).Value);
Working solution 2, but it execute query for each item in the collection.
model.Materials.ToList().ForEach(m => m.Value= db.Material.FirstOrDefault(db_m => db_m.Number.ToString() == m.Number).Value);
Incompletely solution, where i tried to use contains method
// I am trying to get new filtered collection from database, which i will iterate after.
var result = db.Material
.Where(x=>
// here is the reasonable error: cannot convert int into Material class, but i do not know how to solve this.
model.Materials.Contains(x.Number)
)
.Select(material => new Material { Number = material.Number.ToString(), Value = material.Value});
Any idea ? For me it is much easier to execute stored procedure with comma separated id values as a parameter and get the data directly, but i want to master linq too.
I'd do something like this without trying to get too cute :
var numbersToFilterby = model.Materials.Select(m => m.Number).ToArray();
...
var result = from db_m in db.Material where numbersToFilterBy.Contains(db_m.Number) select new { ... }
This seems like it should be easy. Maybe it is and I'm just overthinking it. I have a bunch of items that have a category field set via a DropLink. I want to grab all of the items that match one of those options. E.g., Grab a list of all items where Category=Brochure. I can't seem to get the ID of the Droplink option to match against the Category option on the Item itself.
EDIT: Included current code by request.
public List<PoolDownload> Manuals
{
get
{
LookupField cat = (LookupField)this.Item.Fields["Category"];
return this.Downloads.Where(i => (i.Item.TemplateID == PoolDownload.TemplateId) &&
(i.Item.GlassCast<Pdp.Pool.Website.Business.Entities.PoolDownload>().Category.ToString() == cat.TargetID.ToString()))
.ToList();
}
}
I believe the problem is you're comparing a Guid.ToString() to a Sitecore.Data.ID.ToString(). These two statements return different values:
var guidToString = Sitecore.Context.Item.ID.Guid.ToString();
// "2a6a1d9a-be1d-411b-821a-7e63775280b3"
var idToString = Sitecore.Context.Item.ID.ToString();
// "{2A6A1D9A-BE1D-411B-821A-7E63775280B3}"
Cast the TargetID to a Guid as well and you should be good.
And to answer your question in your comment below about displaying the "Download Items" grouped by Category, you could use the GroupBy method, https://msdn.microsoft.com/en-us/library/bb534304(v=vs.110).aspx like this:
public IEnumerable<IGrouping<Guid, PoolDownload>> Manuals
{
get
{
LookupField cat = (LookupField)this.Item.Fields["Category"];
return this.Downloads.Where(i =>
i.Item.TemplateID == PoolDownload.TemplateId
&& i.Item.GlassCast<Pdp.Pool.Website.Business.Entities.PoolDownload>().Category.ToString() == cat.TargetID.Guid.ToString())
.GroupBy(i => i.Category);
}
}
And then, to loop over the results in the new Manuals property, you could do something like this:
foreach(var categoryGroup in Manuals)
{
var categoryGuid = categoryGroup.Key;
foreach(var download in categoryGroup)
{
var downloadInCurrentGroup = download.Item;
}
}
I'm working on creating a filter for a collection of employees. In order to do this I initially fetch a raw collection of all employees. I clone this list so I can iterate over the original list but remove items from the second list.
For each filter I have, I build a collection of employee ids that pass the filter. Having gone through all filters I then attempt to remove everything that isn't contained in any of these lists from the cloned list.
However for some reason, whenever I attempt to do this using .RemoveAll(), all records seemed to be removed and I can't figure out why.
Here is a stripped down version of the method I'm using, with only 1 filter applied:
public List<int> GetFilteredEmployeeIds(int? brandId)
{
List<int> employeeIds = GetFilteredEmployeeIdsBySearchTerm();
List<int> filteredEmployeeIds = employeeIds.Clone();
// Now filter the results based on which checkboxes are ticked
foreach (var employeeId in employeeIds)
{
// 3rd party API used to get values - please ignore for this example
Member m = new Member(employeeId);
if (m.IsInGroup("Employees"))
{
int memberBrandId = Convert.ToInt32(m.getProperty("brandID").Value);
// Filter by brand
List<int> filteredEmployeeIdsByBrand = new List<int>();
if (brandId != null)
{
if (brandId == memberBrandId)
filteredEmployeeIdsByBrand.Add(m.Id);
var setToRemove = new HashSet<int>(filteredEmployeeIdsByBrand);
filteredEmployeeIds.RemoveAll(x => !setToRemove.Contains(x));
}
}
}
return filteredEmployeeIds;
}
As you can see, I'm basically attempting to remove all records from the cloned record set, wherever the id doesn't match in the second collection. However for some reason every record seems to be getting removed.
Anybody know why?
P.S: Just to clarify, I have put in logging to check the values throughout the process and there are records appearing in the second list, however for whatever reason they're not getting matched in the RemoveAll()
Thanks
Ok only minutes after posting this I realised what I did wrong: The scoping is incorrect. What it should've been was like so:
public List<int> GetFilteredEmployeeIds(int? brandId)
{
List<int> employeeIds = GetFilteredEmployeeIdsBySearchTerm();
List<int> filteredEmployeeIds = employeeIds.Clone();
List<int> filteredEmployeeIdsByBrand = new List<int>();
// Now filter the results based on which checkboxes are ticked
foreach (var employeeId in employeeIds)
{
Member m = new Member(employeeId);
if (m.IsInGroup("Employees"))
{
int memberBrandId = Convert.ToInt32(m.getProperty("brandID").Value);
// Filter by brand
if (brandId != null)
{
if (brandId == memberBrandId)
filteredEmployeeIdsByBrand.Add(m.Id);
}
}
}
var setToRemove = new HashSet<int>(filteredEmployeeIdsByBrand);
filteredEmployeeIds.RemoveAll(x => !setToRemove.Contains(x));
return filteredEmployeeIds;
}
Essentially the removal of entries needed to be done outside the loop of the employee ids :-)
I know that you said your example was stripped down, so maybe this wouldn't suit, but could you do something like the following:
public List<int> GetFilteredEmployeeIds(int? brandId)
{
List<int> employeeIds = GetFilteredEmployeeIdsBySearchTerm();
return employeeIds.Where(e => MemberIsEmployeeWithBrand(e, brandId)).ToList();
}
private bool MemberIsEmployeeWithBrand(int employeeId, int? brandId)
{
Member m = new Member(employeeId);
if (!m.IsInGroup("Employees"))
{
return false;
}
int memberBrandId = Convert.ToInt32(m.getProperty("brandID").Value);
return brandId == memberBrandId;
}
I've just done that off the top of my head, not tested, but if all you need to do is filter the employee ids, then maybe you don't need to clone the original list, just use the Where function to do the filtering on it directly??
Please someone let me know if i've done something blindingly stupid!!
I am trying to make a dynamic linq query that will check for values based on a string.
First of all, here's the query:
objQry = from o in m_Db.OBJECTS.Where(whereConditions)
select o;
if(!objQry.Any())
{
return null;
}
The whereConditions variable is a string I build and pass as parameter to find out the values I need. Here's examples of valid string:
OBJ_NAME == \"Sword\" and OBJ_OWNER == \"Stan\"
This will return any item whose name is "Sword" and owner is "Stan;
OBJ_COLOR == \"Blue\" OR OBJ_COLOR == \"Red\"
This will return any item which color is either blue or red.
Up to there, I'm fine, but now I have a problem: I need to check a decimal field. So I've tried this string:
OBJ_NUMBER == 1
But the query returns null even if there are objects which OBJ_NUMBER value is 1. It's a decimal. How can I indicate the query that they need to check for a decimal value?
**** EDIT ****
I have tried to "modify" the value passed so that it looks like this:
"CARD_NUMBER == Convert.ToDecimal(1)"
And now I have a different kind of error telling me this:
LINQ to Entities does not recognize the method 'System.Decimal ToDecimal(Int32)' method, and this method cannot be translated into a store expression.
Any clues anyone? I'm still looking for a way to do this. Thanks!
EDIT 2
You can get an example of how my code is shaped by looking at this question.
Let's come back at this problem. I want to check decimal values. Let's say that OBJ_NUMBER is a decimal field.
Using Dynamic Linq, I tried to read the decimal field. Say that I want to get each object which number is 1.27. The whereConditions field would then be shaped like this:
OBJ_NUMBER == 1.27
But then I would get an Invalid real literal '1.27' error. I don't know why.
So I have tried Gert Arnold's solution and done this instead:
decimal bDecimal = decimal.Parce(valueToParse);
param = new ObjectParameter("cardNumber", typeof(decimal)) { Value = bDecimal };
valuesToUse.Add("CARD_NUMBER == #cardNumber");
listParams.Add(param);
But I ended up having 2 problems:
The first problem is that my whereConditions string is shaped this way:
CARD_NUMBER == #cardNumber
But I get the following error:
No property or field 'cardNumber' exists in type 'CARD'
Leading me to believe that it cannot make the link between the object parameter and the string used to do the query.
As you can see, I have a list of Params. This is because I cannot know for sure how many parameters the user will chose. So each time the user enters a new search field, I have to create a new ObjectParameter and store it in a list. Here's how I try to do the thing after:
ObjectParameter[] arrayParameters = listParams.ToArray();
// Convert the list to an array
And then, when I try to make the query:
cardQry = from c in mDb.CARD.Where(whereConditions, arrayParameters)
select c;
But to no avail.
RESULTS
Based on the answered question below, I have developped something "awful", yet functional.
First of all, I ignore every decimal fields because I could never reach them with dynamic linq. Instead, I do this:
var valuesToParse = keyValuePair.Value.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
// Here I parse the value and, if that's the case, the symbol.
decimal baseValue = decimal.Parse(valuesToParse[0]);
if (valuesToParse.Count() > 1)
{
string baseMethod = valuesToParse[1];
if (baseMethod == ">" || baseMethod == ">=")
{
if (baseMethod == ">=")
{
baseValue--;
}
// The list is actually like this: Dictionary<string, object> list = new Dictionary<string, object>();
list.Add("low", baseValue);
// I kind of activate a tag telling me that the user is looking for a higher value.
cardHigher = true;
}
else
{
if (baseMethod == "<=")
{
baseValue++;
}
list.Add("low", baseValue);
cardLower = true;
}
}
else
{
//lowParam = new ObjectParameter("dec", typeof(decimal)) { Value = baseValue };
list.Add("low", baseValue);
}
cardNumberActivated = true;
At the end, when I get the list of objects, I do this:
if (list.Count > 0)
{
(example)
if (cardNumberActivated)
{
if (cardHigher)
{
q = mDb.CARD.Where("CARD_NUMBER >= #0", list["low"]).ToList();
}
else if (cardLower)
{
q = mDb.CARD.Where("CARD_NUMBER <= #0", list["low"]).ToList();
}
else
{
q = mDb.CARD.Where("CARD_NUMBER == #0", list["low"]).ToList();
}
}
}
// Here we get the orinalData with the basic filters.
listToReturn.AddRange(cardQry);
if (q != null)
{
//listToReturn.AddRange(q);
for (int i = 0; i < listToReturn.Count; i++)
{
var priceList1 = listToReturn[i];
if (!q.Any(_item => _item.CARD_NUMBER == priceList1.CARD_NUMBER))
{
listToReturn.RemoveAt(i);
i--;
}
}
}
And it works. This is not an elegant way to make it work, but I can validate the fields the way I wanted, and for this, I am thankful at last.
You should not build a query string with inline predicate values. Use parameters in stead. Then will also be able to specify the type:
var whereConditions= "it.CARD_NUMBER = #cardNumber";
var param = new ObjectParameter("cardNumber", typeof(decimal)) { Value = 1 };
objQry = from o in m_Db.OBJECTS.Where(whereConditions, param);
Edit
I don't know what doesn't work in your code. Here's just a random piece of working code derived from one of my own projects:
var param1 = new ObjectParameter("dec", typeof(decimal)) { Value = 90000m };
var param2 = new ObjectParameter("int", typeof(int)) { Value = 90000 };
var q = ValueHolders.Where("it.DecimalValue >= #dec OR it.IntegerValue > #int",
param1, param2).ToList();
Note that param1, param2 could also be an array of ObjectParameter.
I filled some ObservableCollection<Employe> collection:
// Program.Data.Employees - it is ObservableCollection<Employe>.
Program.Data.Employees.Add(new Employe() { Name="Roman", Patronymic="Petrovich", Surname="Ivanov" });
Program.Data.Employees.Add(new Employe() { Name = "Oleg", Patronymic = "Vladimirovich", Surname = "Trofimov" });
Program.Data.Employees.Add(new Employe() { Name = "Anton", Patronymic = "Igorevich", Surname = "Kuznetcov" });
In other place of my code I try to remove some item from this collection:
// Program.Data.Employees - it is ObservableCollection<Employe>.
Employe x = Program.Data.Employees.First(n => n.Guid == emp.Guid); // x is not null.
Int32 index = Program.Data.Employees.IndexOf(x); // I got -1. Why?
Boolean result = Program.Data.Employees.Remove(x); // I got 'false', and item is not removed. Why?
// But this works fine:
Program.Data.Employees.Clear();
I can clear collection, but I can't remove necessary item. Why it happens?
UPD: Equals method of my Employe class
public bool Equals(Employe other) {
return
other.Guid == this.Guid &&
String.Equals(other.Name, this.Name, StringComparison.CurrentCultureIgnoreCase) &&
String.Equals(other.Patronymic == this.Patronymic, StringComparison.CurrentCultureIgnoreCase) &&
String.Equals(other.Surname == this.Surname, StringComparison.CurrentCultureIgnoreCase) &&
other.Sex == this.Sex &&
String.Equals(other.Post == this.Post, StringComparison.CurrentCultureIgnoreCase);
}
I tried the following code to reproduce your error:
class Employee
{
public string Name { get; set; }
public Guid Guid { get; set; }
}
// ...
ObservableCollection<Employee> employees = new ObservableCollection<Employee>();
var guid1 = Guid.NewGuid();
employees.Add(new Employee { Name = "Roman", Guid = guid1 });
employees.Add(new Employee { Name = "Oleg", Guid = Guid.NewGuid() });
var x = employees.First(e => e.Guid == guid1);
var index = employees.IndexOf(x); // index = 0, as expected
var result = employees.Remove(x); // result = true, as expected
It worked as expected. I would suggest, you set a breakpont at var x = ... and check, if
The collection really contains the item you're looking
If First() really returns that item
Then go to the next line and check, if index is returned correctly. And finally check again, if result is really false.
I see several possible causes of your code failing:
You didn't post the full code and something happens between x=Program.Data.Employees.First() and Program.Data.Employees.IndexOf()
You use multithreaded code (which also results in "something happening" between the two statements). In this case, you need to synchronize the access to the collection
You don't use a ObservableCollection directly but some derived class instead which is constructed by your data layer (such as DataServiceCollection, but this one should work fine too). In this case, check the actual type of your collection in the debugger
Another typical cause of errors with collection would be, if you try to remove items while iterating over the collection (i.e. inside a foreachloop): but in this case an exception should be thrown (and IndexOf should work fine), so this would only apply if you use some derived class which implements non-standard behaviour.
EDIT (in return to you posting your Equal method)
Your Equal method has a serious error in it:
String.Equals(other.Patronymic == this.Patronymic, StringComparison.CurrentCultureIgnoreCase)
... // applies also for following comparisons
should be
String.Equals(other.Patronymic, this.Patronymic, StringComparison.CurrentCultureIgnoreCase)
...
Also, if you're using a Guid, consider only comparing the GUIDs, since this usually means 'unique identifier', so it should be enough to identify some entity.