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Circular Reference

Author

Topic

shapper
Constraint Violating Yak Guru

450 Posts

Posted - 2008-09-04 : 10:09:35

Hello,

On an ASP.NET MVC project I am getting a list of Tags which names start with a string contained on the variable "q".

Everything works fine if no Post is related to Tags.
When there is relation I start to get a Circular Reference error.

I have been trying to solve this problem for days!
I can't find the reason for this, either in my SQL or C# code.

I am posting both codes ... just in case:

C# LINQ code:

public JsonResult Filter(string q, int limit) {

var list = (from t in database.Tags
where t.Name.StartsWith(q)
orderby t.Name
select t);
List<Tag> tags = (limit > 0 ? list.Take(limit) : list).ToList();
return this.Json(tags);

}

SQL Tables:


-- Files
create table dbo.Files
(
	FileID uniqueidentifier not null
		constraint PK_File primary key clustered,
	CreatedAt datetime null,
	Description nvarchar(2000) null,
	IsPublished bit null,
	Path nvarchar(800) null,
	Title nvarchar(400) null,
	UpdatedAt datetime null
)

-- Posts
create table dbo.Posts
(
	PostID uniqueidentifier not null
		constraint PK_Post primary key clustered,
	Body nvarchar(max) null,
	CreatedAt datetime null,	
	IsPublished bit null,	
	Title nvarchar(400) null,
	UpdatedAt datetime null
)

-- Tags
create table dbo.Tags
(
	TagID uniqueidentifier not null
	  constraint PK_Tag primary key clustered,
	[Name] nvarchar(100) null
)

-- FilesTags
create table dbo.FilesTags
(
	FileID uniqueidentifier not null,
	TagID uniqueidentifier not null,
		constraint PK_FilesTags
			primary key clustered (FileID, TagID),
		constraint FK_FilesTags_Files
			foreign key(FileID)
			references dbo.Files(FileID)
			on delete cascade,
		constraint FK_FilesTags_Tags
			foreign key(TagID)
			references dbo.Tags(TagID)
			on delete cascade
)

-- PostsTags
create table dbo.PostsTags
(
	PostID uniqueidentifier not null,
	TagID uniqueidentifier not null,
		constraint PK_PostsTags
			primary key clustered (PostID, TagID),
		constraint FK_PostsTags_Posts
			foreign key(PostID)
			references dbo.Posts(PostID)
			on delete cascade,
		constraint FK_PostsTags_Tags
			foreign key(TagID)
			references dbo.Tags(TagID)
			on delete cascade
)

DATA in Tables (All other tables are empty):

Posts

PostID: 78ef0b05-ca4c-4df8-88c9-2858d24fa4e3
Body: <p>Test</p>
CreateAt: 03-09-2008 22:35:25
IsPublished: True
Title: This is the title
UpdatedDate: 03-09-2008 22:35:25

Tags

TagID: e2ec18a7-d668-477b-977b-183989df2a65
Name: Net

TagID: dbf4465a-d0f6-4145-831d-b1ce1363dd16
Name: New York

TagID: 0ea15666-155b-4237-a871-d905a2685f45
Name: Australia

PostsTags

TagID: e2ec18a7-d668-477b-977b-183989df2a65
PostID: 78ef0b05-ca4c-4df8-88c9-2858d24fa4e3

TagID: dbf4465a-d0f6-4145-831d-b1ce1363dd16
PostID: 78ef0b05-ca4c-4df8-88c9-2858d24fa4e3

My Linq code is automaticly generated by LinqToSQL in VS2008.

I don't see any problem in my code or data but I get the error:

A circular reference was detected while serializing an object of type 'MyApp.Models.Post'

I detected the error in FireFox FireBug because the AutoComplete most of the time does not work.

Does anyone sees anything wrong?!

Thanks,
Miguel

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