I'm trying to update definition but facing an exception
SQL Server does not provide comparison of NETXT, XML, Image etc
don't know how to handle it.
My table structure looks like this:
[Table]
public class Dictionary
{
private string _definition;
[Column(IsPrimaryKey = true)]
public string Word
{
get;
set;
}
[Column(CanBeNull = false, Storage="_definition", DbType="NTEXT")]
public string Definition
{
get { return this._definition; }
set { this._definition = value; }
}
}
Here is my update code
using (DictionaryDataContext d8db = new DictionaryDataContext(strConnectionString))
{
IQueryable<Dictionary> DicQuery = from word in d8db.tb_Dictionary where word.Word == w.Word select word;
Dictionary wordShow = DicQuery.FirstOrDefault();
wordShow.Definition = "some string";
d8db.SubmitChanges();
}
Add a rowversion column to your Dictionary class:
[Column(IsVersion = true)]
private Binary _version;
Related
I'm having hard time understanding how to convert an Enum value to it's corresponding name. My model is as follows:
public class CatalogRule
{
public int ID { get; set; }
[Display(Name = "Catalog"), Required]
public int CatalogID { get; set; }
[Display(Name = "Item Rule"), Required]
public ItemType ItemRule { get; set; }
public string Items { get; set; }
[Display(Name = "Price Rule"), Required]
public PriceType PriceRule { get; set; }
[Display(Name = "Value"), Column(TypeName = "MONEY")]
public decimal PriceValue { get; set; }
[Display(Name = "Exclusive?")]
public bool Exclude { get; set; }
}
public enum ItemType
{
Catalog,
Category,
Group,
Item
}
public enum PriceType
{
Catalog,
Price_A,
Price_B,
Price_C
}
A sample result from .net API:
[
{
$id: "1",
$type: "XYZ.CMgr.Models.CatalogRule, XYZ.CMgr",
ID: 1,
CatalogID: 501981,
ItemRule: 0,
Items: "198",
PriceRule: 1,
PriceValue: 0.5,
Exclude: false
},
{
$id: "2",
$type: "XYZ.CMgr.Models.CatalogRule, XYZ.CMgr",
ID: 2,
CatalogID: 501981,
ItemRule: 2,
Items: "9899",
PriceRule: 2,
PriceValue: 10.45,
Exclude: false
}
]
So in this example, I need to get Catalog for results[0].ItemRule & Price A for results[0].PriceRule. How can I accomplish this in BreezeJS??
This is easy to do in ASP.NET Web API, because it is an out-of-box feature in the default JSON serializer (Json.NET).
To see strings instead of enum numbers in JSON, just add an instance of StringEnumConverter to JSON serializer settings during app init:
var jsonFormatter = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
jsonFormatter.SerializerSettings.Converters.Add(new Newtonsoft.Json.Converters.StringEnumConverter());
UPDATE: Yep, you right, this is not help with Breeze.js. Ok, you can anyway do a little magic to make enums work like strings (while new version with fix is not released).
Create a custom ContextProvider which updates all integer enum values in metadata to strings. Here it is:
public class StringEnumEFContextProvider<T> : EFContextProvider<T>
where T : class, new()
{
protected override string BuildJsonMetadata()
{
XDocument xDoc;
if (Context is DbContext)
{
xDoc = GetCsdlFromDbContext(Context);
}
else
{
xDoc = GetCsdlFromObjectContext(Context);
}
var schemaNs = "http://schemas.microsoft.com/ado/2009/11/edm";
foreach (var enumType in xDoc.Descendants(XName.Get("EnumType", schemaNs)))
{
foreach (var member in enumType.Elements(XName.Get("Member", schemaNs)))
{
member.Attribute("Value").Value = member.Attribute("Name").Value;
}
}
return CsdlToJson(xDoc);
}
}
And use it instead of EFContextProvider in your Web API controllers:
private EFContextProvider<BreezeSampleContext> _contextProvider =
new StringEnumEFContextProvider<BreezeSampleContext>();
This works well for me with current Breeze.js version (1.1.3), although I haven't checked other scenarios, like validation...
UPDATE: To fix validation, change data type for enums in breeze.[min|debug].js, manually (DataType.fromEdmDataType function, dt = DataType.String; for enum) or replace default function during app init:
breeze.DataType.fromEdmDataType = function (typeName) {
var dt = null;
var parts = typeName.split(".");
if (parts.length > 1) {
var simpleName = parts[1];
if (simpleName === "image") {
// hack
dt = DataType.Byte;
} else if (parts.length == 2) {
dt = DataType.fromName(simpleName);
if (!dt) {
if (simpleName === "DateTimeOffset") {
dt = DataType.DateTime;
} else {
dt = DataType.Undefined;
}
}
} else {
// enum
dt = DataType.String; // THIS IS A FIX!
}
}
return dt;
};
Dirty, dirty hacks, I know... But that's the solution I found
There will be a new release out in the next few days where we "change" breeze's enum behavior ( i.e. break existing code with regards to enums). In the new release enums are serialized and queried by their .NET names instead of as integers. I will post back here when the new release is out.
For simplicity sake lets assume I have the following two classes:
public class ComplexClass
{
public List<SubClass> SubClasses { get; set; }
public string Name { get; set; }
}
public class SubClass
{
public string Name { get; set; }
}
I have a List<ComplexClass> and I need to build a query based on some parameters.
It's an easy task if all I need to do is use the Name property of ComplexClass. Here's an example:
static IQueryable<ComplexClass> GetQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
query = query.Where(c => c.Name.StartsWith(someParameter));
if (!String.IsNullOrEmpty(someOtherParameter))
query = query.Where(c => c.Name.EndsWith(someOtherParameter));
return query;
}
Based on the parameters I have I can add more query elements. Of course the above example is simple, but the actual problem contains more parameters, and that number can grow.
Things aren't as simple if I want to find those ComplexClass instances which have SubClass instances which meet criteria based on parameters:
static IQueryable<ComplexClass> GetSubQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
if (!String.IsNullOrEmpty(someOtherParameter))
return query.Where(c => c.SubClasses.Where(sc => sc.Name.StartsWith(someParameter) && sc.Name.EndsWith(someOtherParameter)).Any());
else
return query.Where(c => c.SubClasses.Where(sc => sc.Name.StartsWith(someParameter)).Any());
else
if (!String.IsNullOrEmpty(someOtherParameter))
return query.Where(c => c.SubClasses.Where(sc => sc.Name.EndsWith(someOtherParameter)).Any());
else
return null;
}
I can no longer just add bits of the query based on each parameter, I now need to write the whole query in one go, and this means I need to check every combination of parameters, which is hardly ideal.
I suspect the key is to build an Expression class and create a lambda expression from that, but I'm not sure how to tackle the problem.
Any suggestions? :)
EDIT:
My initial idea was this:
static IQueryable<ComplexClass> GetSubQuery(string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
query = query.Where(c =>
{
var subQuery = c.SubClasses.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
subQuery = subQuery.Where(sc => sc.Name.StartsWith(someParameter));
if (!String.IsNullOrEmpty(someOtherParameter))
subQuery = subQuery.Where(sc => sc.Name.EndsWith(someOtherParameter));
return subQuery.Any();
});
return query;
}
This works in my small console test application as it's using LINQ to Objects. Unfortunately, I need to use Entity Framework and LINQ to Entities, which causes an implementation similar to the one above to throw a A lambda expression with a statement body cannot be converted to an expression tree error message.
I'm assuming that in you real-life code the SubClasses property is IQueryable<SubClass> rather than List<SubClass>?
If so, then your query building becomes easy:
static IQueryable<ComplexClass> GetSubQuery(
string someParameter, string someOtherParameter)
{
var query = list.AsQueryable();
if (!String.IsNullOrEmpty(someParameter))
query = query.Where(c => c.SubClasses
.Where(sc => sc.Name.StartsWith(someParameter)).Any());
if (!String.IsNullOrEmpty(someOtherParameter))
query = query.Where(c => c.SubClasses
.Where(sc => sc.Name.StartsWith(someOtherParameter)).Any());
return query;
}
Mixing IEnumerable<T> and IQueryable<T> using AsQueryable() is never a good idea.
I implemented my solution in a simple Console Project:
internal class Program
{
#region Constants and Fields
private static readonly List<ComplexClass> list = new List<ComplexClass>
{
new ComplexClass
{
Name = "complex",
SubClasses = new List<SubClass>
{
new SubClass
{
SubName = "foobar"
}
}
},
new ComplexClass
{
Name = "complex",
SubClasses = new List<SubClass>
{
new SubClass
{
SubName = "notfoobar"
}
}
}
};
#endregion
#region Public Methods
public static void Main(string[] args)
{
Console.WriteLine("foo / bar :");
GetSubQuery("foo", "bar");
Console.WriteLine();
Console.WriteLine("foo / null :");
GetSubQuery("foo", null);
Console.WriteLine();
Console.WriteLine("string.Empty / bar :");
GetSubQuery(string.Empty, "bar");
Console.WriteLine();
Console.WriteLine("maeh / bar :");
GetSubQuery("maeh", "bar");
Console.ReadKey();
}
#endregion
#region Methods
private static void GetSubQuery(string startsWith,
string endsWith)
{
var query = from item in list
let StartIsNull = string.IsNullOrEmpty(startsWith)
let EndIsNull = string.IsNullOrEmpty(endsWith)
where
(StartIsNull || item.SubClasses.Any(sc => sc.SubName.StartsWith(startsWith)))
&& (EndIsNull || item.SubClasses.Any(sc => sc.SubName.EndsWith(endsWith)))
select item;
foreach (var complexClass in query)
{
Console.WriteLine(complexClass.SubClasses.First().SubName);
}
}
#endregion
public class ComplexClass
{
#region Public Properties
public string Name { get; set; }
public List<SubClass> SubClasses { get; set; }
#endregion
}
public class SubClass
{
#region Public Properties
public string SubName { get; set; }
#endregion
}
}
The Console Output is:
foo / bar :
foobar
foo / null :
foobar
string.Empty / bar :
foobar
notfoobar
maeh / bar :
MVC3, Entity Framework 4.1 Code first.
Working with 2 tables
Model:
public class UniversityMaster
{
[Key]
public string UniversityId { get; set; }
public string UniversityName { get; set; }
}
public class ProgramMaster
{
[Key]
public string ProgramId { get; set; }
public string ProgramName { get; set; }
public string UniversityId { get; set; }
public virtual UniversityMaster University { get; set; } // navigation property
}
Dynamic expression for sorting (just to avoid a switch case statement):
public virtual IQueryable< ProgramMaster > GetQueryableSort(string sortField="", string sortDirection="")
{
IQueryable<ProgramMaster> query = _dbSet;
ParameterExpression pe = Expression.Parameter(typeof(ProgramMaster), string.Empty);
MemberExpression property = Expression.PropertyOrField(pe, sortField);
//get a exception here if the sort field is of navigation property (University.UniversityName)
LambdaExpression lambda = Expression.Lambda(property, pe);
if (sortDirection == "ASC")
orderbydir = "OrderBy";
else
orderbydir = "OrderByDescending";
MethodCallExpression call = Expression.Call(typeof(Queryable),
orderbydir, new Type[] { typeof(TEntity), property.Type }, query.Expression, Expression.Quote(lambda));
var returnquery = (IOrderedQueryable<ProgramMaster>)query.Provider.CreateQuery< ProgramMaster >(call);
return returnquery;
}
The page is displaying a grid with two columns Program Name and University Name using webgrid. The sorting work fine for Program Name column, however fails if sorted by University Name as this property is in UniversityMaster and the Expression.PropertyOrField searches this property in ProgramMaster. Here is the exception:
University.UniversityName' is not a member of type 'App.Core.Model.ProgramMaster
My question is how I make this work for navigation properties of my model class.
Hope I was able explain the scenario. Any help is appreciated.
Well that's because the MemberExpression is trying to call a member named Univerty.UniversityName on the parameter. What you want to do is call a member named Univerity on the parameter, then call UniversityName on that. Effectively, you need to iteratively resolve the property names.
public virtual IQueryable< ProgramMaster > GetQueryableSort(string sortField = "", string sortDirection = "")
{
IQueryable<ProgramMaster> query = _dbSet;
var propertyNames = sortField.Split(".");
ParameterExpression pe = Expression.Parameter(typeof(ProgramMaster), string.Empty);
Expression property = pe;
foreach(var prop in propertyName)
{
property = Expression.PropertyOrField(property, prop);
}
LambdaExpression lambda = Expression.Lambda(property, pe);
if (sortDirection == "ASC")
orderbydir = "OrderBy";
else
orderbydir = "OrderByDescending";
MethodCallExpression call = Expression.Call(
typeof(Queryable),
orderbydir,
new Type[] { typeof(TEntity), property.Type },
query.Expression,
Expression.Quote(lambda));
var returnquery = (IOrderedQueryable<ProgramMaster>)query.Provider.CreateQuery<ProgramMaster>(call);
return returnquery;
}
Microsoft has a DynamicQueryable class which can be used to dynamically construct certain portions of a LINQ query using strings. With this you can say myQuery.OrderBy("University.UniversityName") and it will handle building the expression. The same library also supports dynamic construction of SELECT and WHERE clauses.
You can find a copy of the source as part of the excellent EntityFramework.Extended package by Loresoft. Microsoft's file is at https://github.com/loresoft/EntityFramework.Extended/blob/master/Source/EntityFramework.Extended/Dynamic/DynamicQueryable.cs
I use Cache Aspect with ASP.NET Cache. I need create condition based on ReturnValue.
I simplified my problem. I use CacheResult aspect on method wich return simple POCO object.
Here is definition:
public class MyData
{
public string MyProperty { get; set; }
}
public class MyResponse
{
public int MyId { get; set; }
public MyData [] Result { get; set; }
}
I need create condition for cache - Cache result only if MyResponse.MyData.Lenght is bigger then batch limit.
[CacheResult("AspNetCache", "'MyResponse.MyId=' + #id",
Condition = "MyResponse.Result.Length > #batchLimit")]
public MyResponse GetResponse(int id, int batchLimit)
{
Thread.Sleep(5000);
return new MyResponse
{
MyId = 1,
Result =
new MyData[]
{
new MyData {MyProperty = "A"}, new MyData {MyProperty = "B"},
new MyData {MyProperty = "C"},
}
};
}
I tried this definition of condition:
Condition = "MyResponse.Result.Length > #batchLimit"
I got this error:
'MyResponse' node cannot be resolved for the specified context
[Sample.MyResponse].
So I tried second version:
Condition = "'MyResponse.Result.Length' > #batchLimit"
Finished with error:
Cannot compare instances of [System.String] and [System.Int32] because they cannot be coerced to the same type.
I google it I can use keyword ReturnValue something like this:
Condition = "#ReturnValue != null"
But I don't know how I can access to MyResponse.MyData.Length.
the context for the evaluation of the condition expression is the return value, so just do this:
Condition = "Result.Length > #batchLimit"
equivalent to
Condition = "#root.Result.Length > #batchLimit"
I would like to perform LINQ to SQL mapping in C#, in a many-to-many relationship, but where data is not mandatory.
To be clear:
I have a news site/blog, and there's a table called Posts. A blog can relate to many categories at once, so there is a table called CategoriesPosts that links with foreign keys with the Posts table and with Categories table. I've made each table with an identity primary key, an id field in each one, if it matters in this case.
In C# I defined a class for each table, defined each field as explicitly as possible. The Post class, as well as Category class, have a EntitySet to link to CategoryPost objects, and CategoryPost class has 2 EntityRef members to link to 2 objects of each other type.
The problem is that a Post may relate or not to any category, as well as a category may have posts in it or not. I didn't find a way to make an EntitySet<CategoryPost?> or something like that.
So when I added the first post, all went well with not a single SQL statement. Also, this post was present in the output. When I tried to add the second post I got an exception, Object reference not set to an instance of an object, regarding to the CategoryPost member.
Post:
[Table(Name="tm_posts")]
public class Post : IDataErrorInfo
{
public Post()
{
//Initialization of NOT NULL fields with their default values
}
[Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)]
public int ID { get; set; }
private EntitySet<CategoryPost> _categoryRef = new EntitySet<CategoryPost>();
[Association(Name = "tm_rel_categories_posts_fk2", IsForeignKey = true, Storage = "_categoryRef", ThisKey = "ID", OtherKey = "PostID")]
public EntitySet<CategoryPost> CategoryRef
{
get { return _categoryRef; }
set { _categoryRef.Assign(value); }
}
}
CategoryPost
[Table(Name = "tm_rel_categories_posts")]
public class CategoryPost
{
[Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)]
public int ID { get; set; }
[Column(Name = "fk_post", DbType = "int", CanBeNull = false)]
public int PostID { get; set; }
[Column(Name = "fk_category", DbType = "int", CanBeNull = false)]
public int CategoryID { get; set; }
private EntityRef<Post> _post = new EntityRef<Post>();
[Association(Name = "tm_rel_categories_posts_fk2", IsForeignKey = true, Storage = "_post", ThisKey = "PostID", OtherKey = "ID")]
public Post Post
{
get { return _post.Entity; }
set { _post.Entity = value; }
}
private EntityRef<Category> _category = new EntityRef<Category>();
[Association(Name = "tm_rel_categories_posts_fk", IsForeignKey = true, Storage = "_category", ThisKey = "CategoryID", OtherKey = "ID")]
public Category Category
{
get { return _category.Entity; }
set { _category.Entity = value; }
}
}
Category
[Table(Name="tm_categories")]
public class Category
{
[Column(Name = "id", DbType = "int", CanBeNull = false, IsDbGenerated = true, IsPrimaryKey = true)]
public int ID { get; set; }
[Column(Name = "fk_parent", DbType = "int", CanBeNull = true)]
public int ParentID { get; set; }
private EntityRef<Category> _parent = new EntityRef<Category>();
[Association(Name = "tm_posts_fk2", IsForeignKey = true, Storage = "_parent", ThisKey = "ParentID", OtherKey = "ID")]
public Category Parent
{
get { return _parent.Entity; }
set { _parent.Entity = value; }
}
[Column(Name = "name", DbType = "varchar(100)", CanBeNull = false)]
public string Name { get; set; }
}
So what am I doing wrong? How to make it possible to insert a post that doesn't belong to any category? How to insert categories with no posts?
It seems that the error has nothing to do with mapping. Mapping is correct.
As I wrote, the first post got inserted without problems, and the rest failed to insert. After deleting it from the database, I still couldn't add posts. It became clear that it had nothing to do with either I had something in the DB or not, and only with the fact that I've made some changes to the code.
So what are the changes? In Apress "ASP.NET MVC Pro", the first example illustrated a way to validate data in an iterative way (non-declarative, using the facilities provided by IDataErrorInfo), to which I stuck. I done everything by that example, and the function call that should have validated the input screwed up my data flow, and threw that exception upon submitting to the database.
Removed that validation, and everything worked fine.
Sorry for the false alarms.