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SQL LINQ query keeps looping through two tables

I am trying to call a linq query in asp.net 5. However, my query results in an infinite loop of data between two tables.
Logs (logs_historical)
meterID (FK)
log_data
-----
Meters
meter_uid (PK)
My goal is to have multiple logs related to one meter.
Relationships
Foreign key Base Table = logs
Foreign key Column = meterID
Primary Base Table = meters
Primary Key Colum = meterID
This is my linq query
records = dbContext.logs.Where(e =>(e.timestamp.Value.Month == inputDate.Month)).ToList() ;
1) This screenshot shows the table information and (foreign key table)
When I look into the foreign key table information, it also has the logs.
Going into the logs will show the same table from picture (1)
2)
I'm sure this was asked before, but I do not know what this problem is called. I am new to databases. Thanks for any advice!

As a quick fix, you can probably use dbContext.Configuration.LazyLoadingEnabled = false;
just before your query. You can disable it globally as well.
What happens is Entity Framework will eagerly load all related entities. If you have entities that go several levels deep, or that reference each other, well, as you have experienced, it will continue to follow those relationships. Disabling lazy loading will prevent this. Please note that you will have to explicitly declare anything you want included via the .include() function.
The other option is to redesign your database so that this isn't the case, but sometimes that just isn't feasible. I don't really know the intricate workings of your project, so I am speculating here.
EDIT:
I forgot to add, if you go into the model browser and explore the models that were created for you by Entity Framework, you will find those relationships that are causing the issue. If you are using code first, you can easily fix this. If you are using database first, you are somewhat at the mercy of how EF interprets relationships.

Code first of EF, how to define navigation property relationship without setting foreign key between table in database

I use code first of Entity framework. There are two classes "Question" and "User". I defined a relationship as below:
this.HasRequired(v => v.Creator).WithMany(v => v.Questiones)
.HasForeignKey(v => v.CreatorId).WillCascadeOnDelete(false);
After gernerating the database I found that it always create foreign key between Id of User and CreatorId of Question. Because of lower performance of FK(and other reason),I want to define navigation property relationship without setting foreign key in database? Delete FK after EF created it?
If cannot do this using fluent api, could you tell me why EF designed in this way please?
About the lower performance of FK. I have a User table with 5 Million records in it. when I insert a Question into db, since the db check the question.CreatorId validation from User table, it always slower than without FK.
And there are many other reasons that I need to remove FK.
I think I am somewhat obsession because I think that deleting FK after created it is strangely and ugly. What i want is implementing this by using something like WithoutForeignKey in fluent api:
this.HasRequired(v => v.Creator).WithMany(v => v.Questiones)
.WithoutForeignKey(v => v.CreatorId).WillCascadeOnDelete(false);

Without questioning why are you trying to do this strange thing and going just to the answer: you could delete fk constraint after generated, or you could use migrations and remove FK generation from the migration code.
SQL code generated when traversing nav properties will work even if fk constraint doesn't exist, except for cascade deleting

If you want a relationship between two tables, you need to define a foreign key. No way around it. Even if you use Map() in fluent api, you can only hide the foreign key in your model, in the background EF will still use it and it will exist in the database.
Also I don't get what you mean by "performance" of foreign key? One extra (likely small) column won't make a difference. If you mean the navigation properties for the performance part, you can do 3 things:
Don't include them in your model
Make them non-virtual to disable lazy loading
Disable lazy loading all together with ctx.Configuration.LazyLoadingEnabled = false;

If you don't want to tell db about relation and treat both entities as not related (I wonder why), then just ignore these navigation properties and FK field. Note that you will be responsible for managing related entities: saving and loading them from db, updating ids etc
this.Ignore(q => q.Creator);
this.Ignore(q => q.CreatorId);
And you also need to ignore other side of relation, otherwise EF will generate FK column with default name Creator_CreatorId. So in Creator entity configuration:
this.Ignore(c => c.Questiones);

EF DB-first mapping mess

I have a frustrating situation owing to this little quirk of EF. Here's a simple demo of the behavior. First the DB schema:
As you see, RestrictedProduct is a special case of product, which I'm intending to make a subclass of Product with some special code.
Now I import to an EF data model:
Oops! EF saw that RestrictedProduct had only 2 fields, both FKs, so it mapped it as a one-to-many relationship between Product and Restriction. So I go back to the database and add a Dummy field to RestrictedProduct, and now my EF model looks much better:
But that Dummy field is silly and pointless. Maybe I could delete it? I blow away the field from the DB table and the entity model, then refresh the model from the DB...
Oh, no! The Product-Restriction association is back, under a new name (RestrictedProduct1)! Plus, it won't compile:
Error 3034: Problem in mapping fragments starting at lines (x, y) :Two entities with possibly different keys are mapped to the same row. Ensure these two mapping fragments map both ends of the AssociationSet to the corresponding columns.
Is there any way to prevent this behavior, short of keeping the Dummy field on the RestrictedProduct table?

I just came across the same issue, and as an alternative to putting the dummy field in your RestrictedProduct table to force the creation of an entity you can also make your RestrictedProduct.RestrictionId field nullable and EF will then generate an entity for it. You can then modify it to use inheritance and any subsequent "Update model from database" will not cause undesired nav properties. Not really a nice solution but a work around.

Let's walk slowly into your problem.
1st thing you need to decide is if the restricted product is
really a special case of product or is it a possible extension
to each product.
From your original DB Scheme it seems that any product may have
a relation to a single restriction however a single restriction
can be shared among many products.. so this is a simple 1 to many
situation which means that restricted product is NOT a special case
of product! Restriction is an independent entity which has nothing
to do with product in a specific way.
Therefore EF is correct in the 1st importation of your scheme:
1. a product can have 0 or 1 restrictions.
2. a restriction is another entity which can be related to many products.
I do not see your problem.

Modelling polymorphic associations database-first vs code-first

We have a database in which one table contains records that can be child to several other tables. It has a "soft" foreign key consisting of the owner's Id and a table name. This (anti) pattern is know as "polymorphic associations". We know it's not the best database design ever and we will change it in due time, but not in the near future. Let me show a simplified example:
Both Event, Person, and Product have records in Comment. As you see, there are no hard FK constraints.
In Entity Framework it is possible to support this model by sublassing Comment into EventComment etc. and let Event have an EventComments collection, etc.:
The subclasses and the associations are added manually after generating the basic model from the database. OwnerCode is the discriminator in this TPH model. Please note that Event, Person, and Product are completely different entities. It does not make sense to have a common base class for them.
This is database-first. Our real-life model works like this, no problem.
OK. Now we want to move to code-first. So I started out reverse-engineering the database into a code first model (EF Power Tools) and went on creating the subclasses and mapping the associations and inheritance. Tried to connect to the model in Linqpad. That's when the trouble started.
When trying to execute a query with this model it throws an InvalidOperationExeception
The foreign key component 'OwnerId' is not a declared property on type 'EventComment'. Verify that it has not been explicitly excluded from the model and that it is a valid primitive property.
This happens when I have bidirectional associations and OwnerId is mapped as a property in Comment. The mapping in my EventMap class (EntityTypeConfiguration<Event>) looks like this:
this.HasMany(x => x.Comments).WithRequired(c => c.Event)
.HasForeignKey(c => c.OwnerId);
So I tried to map the association without OwnerId in the model:
this.HasMany(x => x.Comments).WithRequired().Map(m => m.MapKey("OwnerId"));
This throws a MetaDataException
Schema specified is not valid. Errors:
(10,6) : error 0019: Each property name in a type must be unique. Property name 'OwnerId' was already defined.
(11,6) : error 0019: Each property name in a type must be unique. Property name 'OwnerId' was already defined.
If I remove two of the three entity-comment associations it is OK, but of course that's not a cure.
Some further details:
It is possible to create a working DbContext model ("code second") from the edmx by adding a DbContext generator item. (this would be a work-around for the time being).
When I export the working code-first model (with one association) to edmx (EdmxWriter) the association appears to be in the storage model, whereas in the original edmx they are part of the conceptual model.
So, how can I create this model code-first? I think the key is how to instruct code-first to map the associations in the conceptual model, not the storage model.

I personally stick with Database first when using EF on any schema that is this level of complexity. I have had issues with complex schemas in regards to code first. Maybe the newer versions are a little better, but worrying how to try and code complex relationships seems less straight forward then allowing the engine to generate it for you. Also when a relationship gets this complex I tend to avoid trying to generate it with EF and try and use stored procedures for easier troubleshooting of performance bottlenecks that can arise.

Error in updating edmx file

I am getting an error when I am updating the edmx file.
Error 3002: Problem in Mapping Fragment starting at line 3828:
Potential runtime violation of table Archive's keys (Archive.UserID):
Columns (Archive.UserID) are mapped to EntitySet Archive's properties
(Archive.UserID) on the conceptual side but they do not form the
EntitySet's key properties (Archive.ListID, Archive.UserID).
Any idea how to resolve this?

Check the mapping between the two tables. It sounds like the properties are mapped to the wrong field.
Take a look at: http://cticoder.wordpress.com/2008/10/14/entity-framework-error-3002-error-3003/