Problems deleting queried table entities

Question

Getting started with Azure development using the C#SDK. Everything else is working out, but trying to delete stuff always results in 404, not found exception. What we do is
Query entire partition (partition key is one user ID) for all purchases 
Create a list of results by creating new instances of a TableEntity subclass by copying properties, PartitionKey, RowKey, ETag and Timestamp from each DynamicTableEntity result
Filter the list
Call delete operation for each list item 
We're working on a test table with just one partition and two rows in debugging everything seems to be OK. I.e. all data comes out as it should, keys and ETag and timestamp are non-null and it matches what I see in Azure Storage Explorer. I've also tried
using both queried value and "*" for ETag. But still when trying to delete, it's 'not found'. Is there some basic concept I'm missing? 

Answer 1

The way I understand DynamicTableEntity is that it just prevents serialization/deserialization of properties into a c# type/class.  Instead of asking for a UserEntity, and then CompanyEntity in two queries (for example) you could use a DynamicTableEntity
and gather both types of classes in one query.  In contrast, a TableServiceEntity specifies a specific class type to query, and can only get one object type (but can get multiple objects of that type at a time.)  To get UserEntities and CompanyEntities
from the same table, I'd have to do two queries, specifying each type on the .Query() call.  That's really the benefit of DynamicTableEntity.
Now, the tracking of entities is handled by the tablecontext you use.  When you query a table using DynamicTableEntity or TableServiceEntity, objects using PK, RK and ETAG, are loaded and stored (unless NoTracking is set.) in the Context's Entities
Collection.  Put a breakpoint after your .Query call, and look at the Context's Entities collection - you'll see what I mean.
When you later .Update, .Delete or .Insert an entity into that collection, the change state is stored and tracked.  When you later call SaveChangesWithRetries or similar function, the entities in the collection are checked for those updated state flags
and then updated, deleted or inserted, as appropriate, and with respect the etag.
So, you query.  An entity object of some sort is placed in the Entities collection.  You're stating that you make a copy of that data into another object.  You then call Update, but the entity's object isn't in the .Entities collection - you
have a new c# object on your hands and object.Equals fails. (it is the same PK, RK Entity object in terms of Azure though!)
Whew.  Does that make any sense at all?
Darin R.