Obvious attempt here is to get phone calls by a specific account ID, and ONLY phonecalls which have a regardingobject type of "account" (this is only a basic part of the full call, but even this fails).
var linqPhonecalls = from pc in svcContext.PhoneCallSet
where ((pc.RegardingObjectId.Id == account.Id) && (pc.RegardingObjectId.LogicalName == "account"))
select new
{
subj = pc.Subject,
stateCD = pc.StateCode,
};
Through research on the net I ran into this idea ( http://informeddynamicscrm.blogspot.com/2012/01/linq-restrictions-with-crm-2011-xrm.html ) and tried the following:
pc.RegardingObjectId.LogicalName.Equals("account") == true
As well as using Contains() and any other comparison operations I could try. It seems like the major problem here is the use of .LogicalName (also tried .Name)
Because I can't get it to work, I'm going to leave that check out of the equation for now, but I'd really like to put it in there because I'm going to be joining against other regarding types and want to sort things out.
Related
everyone! ))
Here is code.
var existingEntities = (from record in globalOne.serviceContext.records_out
where record.timestamp.Date == DateTime.Now.Date
select record ).ToList();
It doesn't work.
Another code:
var existingEntities = (from record in globalOne.serviceContext.records_out
where record.timestamp.Day == DateTime.Now.Day
select record ).ToList();
It does work.
So, problem id in next string:
where record.timestamp.**Date** == DateTime.Now.Date
also won't do
where record.timestamp.Date.Equals(DateTime.Now.Date)
But why? I have no clue. "Timestamp" field is dateTime field in MS SQL SERVER.
And - there is NO records in table.
And I almost forgot - what does it mean - "doesn't work".
App just will not reach the breakpoint after that query(first), without any error, without anything.
Thanks.
You can call record.timestamp.Date because EF can't convert it to required expression tree (then convert it to sql command). In fact EF supports limited number of functions and properties, But for DateTime, EF has some good Canonical functions. You can use them in your case, e.g you can use Day(),Month(),Year() functions to solve your problem (see the link).
var crm = new XrmDataContext("Crm");
var properties = from property in crm.awx_propertyawx_properties
orderby property.awx_name
select new {
awx_name = property.awx_name == null ? "no name" : property.awx_name
}
;
properties = properties.Where(a => a.awx_name.StartsWith("Sears Tower"));
I get the error "Cannot determine the attribute name" - what am I doing wrong here? I read in plenty of threads that this is perfectly okay to do. HELP!
I too spent quite a while trying to find a way of issuing dynamic where clauses against the CRM system.
I tried similar syntax above and also built a predicate builder. Both did not work.
In the end I had to take a 2 stage approach.
1. Pull a superset from CRM using static where clause into a collection
2. Query dynamically from my in memory collection using standard techniques.
I hate CRM.
Phil
I have this query:
var iterator = criteria.binaryAssetBranchNodeIds.GetEnumerator();
iterator.MoveNext();
var binaryAssetStructures = from bas in db.BinaryAssetStructures
where bas.BinaryAssetStructureId == iterator.Current
select bas;
When I iterate over the binaryAssetStructureIds with a foreach loop no problems occur. When I try this
var binaryAssetStructure = binaryAssetStructures.ElementAt(0);
I get following error:
Unable to cast object of type 'System.Linq.Expressions.MethodCallExpression' to type 'SubSonic.Linq.Structure.ProjectionExpression'
First() for example does work... What am I missing here...
I don't know SubSonic at all, but FWIW a similar issue exists with the Entity Framework. In that case it boils down to the fact that there's no direct translation of ElementAt to SQL.
First() can be easily translated to SELECT TOP 1 FROM ... ORDER BY ..., but the same is not easily expressed for ElementAt.
You could argue that e.g. ElementAt(5) should be translated to SELECT TOP 5 FROM ... ORDER BY ... and then the first four elements simply discarded, but that doesn't work very well if you ask for ElementAt(100000).
In EF, you can partialle overcome this issue forcing the expression to be evaluated first, which can be done with calls to AsEnumerable, ToList or ToArray.
For example
var binaryAssetStructure = binaryAssetStructures.AsEnumerable().ElementAt(0);
I hope this helps although not explicitly directed at SubSonic.
I'm trying to do a query like so...
query.Where(x => !string.IsNullOrEmpty(x.PropertyName));
but it fails...
so for now I have implemented the following, which works...
query.Where(x => (x.PropertyName ?? string.Empty) != string.Empty);
is there a better (more native?) way that LINQ handles this?
EDIT
apologize! didn't include the provider... This is using LINQ to SQL
http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=367077
Problem Statement
It's possible to write LINQ to SQL that gets all rows that have either null or an empty string in a given field, but it's not possible to use string.IsNullOrEmpty to do it, even though many other string methods map to LINQ to SQL.
Proposed Solution
Allow string.IsNullOrEmpty in a LINQ to SQL where clause so that these two queries have the same result:
var fieldNullOrEmpty =
from item in db.SomeTable
where item.SomeField == null || item.SomeField.Equals(string.Empty)
select item;
var fieldNullOrEmpty2 =
from item in db.SomeTable
where string.IsNullOrEmpty(item.SomeField)
select item;
Other Reading:
1. DevArt
2. Dervalp.com
3. StackOverflow Post
This won't fail on Linq2Objects, but it will fail for Linq2SQL, so I am assuming that you are talking about the SQL provider or something similar.
The reason has to do with the way that the SQL provider handles your lambda expression. It doesn't take it as a function Func<P,T>, but an expression Expression<Func<P,T>>. It takes that expression tree and translates it so an actual SQL statement, which it sends off to the server.
The translator knows how to handle basic operators, but it doesn't know how to handle methods on objects. It doesn't know that IsNullOrEmpty(x) translates to return x == null || x == string.empty. That has to be done explicitly for the translation to SQL to take place.
This will work fine with Linq to Objects. However, some LINQ providers have difficulty running CLR methods as part of the query. This is expecially true of some database providers.
The problem is that the DB providers try to move and compile the LINQ query as a database query, to prevent pulling all of the objects across the wire. This is a good thing, but does occasionally restrict the flexibility in your predicates.
Unfortunately, without checking the provider documentation, it's difficult to always know exactly what will or will not be supported directly in the provider. It looks like your provider allows comparisons, but not the string check. I'd guess that, in your case, this is probably about as good of an approach as you can get. (It's really not that different from the IsNullOrEmpty check, other than creating the "string.Empty" instance for comparison, but that's minor.)
... 12 years ago :) But still, some one may found it helpful:
Often it is good to check white spaces too
query.Where(x => !string.IsNullOrWhiteSpace(x.PropertyName));
it will converted to sql as:
WHERE [x].[PropertyName] IS NOT NULL AND ((LTRIM(RTRIM([x].[PropertyName])) <> N'') OR [x].[PropertyName] IS NULL)
or other way:
query.Where(x => string.Compare(x.PropertyName," ") > 0);
will be converted to sql as:
WHERE [x].[PropertyName] > N' '
If you want to go change the type of the collection from nullable type IEnumerable<T?> to non-null type IEnumerable<T> you can use .OfType<T>().
.OfType<T>() will remove null values and return a list of the type T.
Example: If you have a list of nullable strings: List<string?> you can change the type of the list to string by using OfType<string() as in the below example:
List<string?> nullableStrings = new List<string?> { "test1", null, "test2" };
List<string> strings = nullableStrings.OfType<string>().ToList();
// strings now only contains { "test1", "test2" }
This will result in a list of strings only containing test1 and test2.
Why do I get the error:
Unable to create a constant value of type 'Closure type'. Only
primitive types (for instance Int32, String and Guid) are supported in
this context.
When I try to enumerate the following Linq query?
IEnumerable<string> searchList = GetSearchList();
using (HREntities entities = new HREntities())
{
var myList = from person in entities.vSearchPeople
where upperSearchList.All( (person.FirstName + person.LastName) .Contains).ToList();
}
Update:
If I try the following just to try to isolate the problem, I get the same error:
where upperSearchList.All(arg => arg == arg)
So it looks like the problem is with the All method, right? Any suggestions?
It looks like you're trying to do the equivalent of a "WHERE...IN" condition. Check out How to write 'WHERE IN' style queries using LINQ to Entities for an example of how to do that type of query with LINQ to Entities.
Also, I think the error message is particularly unhelpful in this case because .Contains is not followed by parentheses, which causes the compiler to recognize the whole predicate as a lambda expression.
I've spent the last 6 months battling this limitation with EF 3.5 and while I'm not the smartest person in the world, I'm pretty sure I have something useful to offer on this topic.
The SQL generated by growing a 50 mile high tree of "OR style" expressions will result in a poor query execution plan. I'm dealing with a few million rows and the impact is substantial.
There is a little hack I found to do a SQL 'in' that helps if you are just looking for a bunch of entities by id:
private IEnumerable<Entity1> getByIds(IEnumerable<int> ids)
{
string idList = string.Join(",", ids.ToList().ConvertAll<string>(id => id.ToString()).ToArray());
return dbContext.Entity1.Where("it.pkIDColumn IN {" + idList + "}");
}
where pkIDColumn is your primary key id column name of your Entity1 table.
BUT KEEP READING!
This is fine, but it requires that I already have the ids of what I need to find. Sometimes I just want my expressions to reach into other relations and what I do have is criteria for those connected relations.
If I had more time I would try to represent this visually, but I don't so just study this sentence a moment: Consider a schema with a Person, GovernmentId, and GovernmentIdType tables. Andrew Tappert (Person) has two id cards (GovernmentId), one from Oregon (GovernmentIdType) and one from Washington (GovernmentIdType).
Now generate an edmx from it.
Now imagine you want to find all the people having a certain ID value, say 1234567.
This can be accomplished with a single database hit with this:
dbContext context = new dbContext();
string idValue = "1234567";
Expression<Func<Person,bool>> expr =
person => person.GovernmentID.Any(gid => gid.gi_value.Contains(idValue));
IEnumerable<Person> people = context.Person.AsQueryable().Where(expr);
Do you see the subquery here? The generated sql will use 'joins' instead of sub-queries, but the effect is the same. These days SQL server optimizes subqueries into joins under the covers anyway, but anyway...
The key to this working is the .Any inside the expression.
I have found the cause of the error (I am using Framework 4.5). The problem is, that EF a complex type, that is passed in the "Contains"-parameter, can not translate into an SQL query. EF can use in a SQL query only simple types such as int, string...
this.GetAll().Where(p => !assignedFunctions.Contains(p))
GetAll provides a list of objects with a complex type (for example: "Function"). So therefore, I would try here to receive an instance of this complex type in my SQL query, which naturally can not work!
If I can extract from my list, parameters which are suited to my search, I can use:
var idList = assignedFunctions.Select(f => f.FunctionId);
this.GetAll().Where(p => !idList.Contains(p.FunktionId))
Now EF no longer has the complex type "Function" to work, but eg with a simple type (long). And that works fine!
I got this error message when my array object used in the .All function is null
After I initialized the array object, (upperSearchList in your case), the error is gone
The error message was misleading in this case
where upperSearchList.All(arg => person.someproperty.StartsWith(arg)))