I am using neo4j OGM for CRUD operations. But when I use session.save(entity, 0) where entity has only id and updated attribute, other attributes associated with entity are deleted fro neo4j entity.
For example Object car has id, name and year.
If I just set id and year in entity, name attribute will be deleted, which i donot want.
I donot want to fetch and update.
To preserve existing values in the database, you have to load first the data.
This is the way all OGM / ORM work.
To update just specific attributes you can use a dedicated cypher query.
Related
Looking to see if there is a way to filter out logical/soft deleted entities by default, but also is overridable so that I can fetch all entities as needed?
I implemented core data in my app with 2 Entity named "Employees" & "Departments".
They have a relationship with many to many. But no action for deletion now on relationship.
Now, I need like if any department has no employee then that department will automatically delete from DB.
Is this possible?
Thanks for your time :)
It is not possible to delete automatically if we have a trouble to fetch u need to filter the data using predicate matching with your requirements .
I am new to the Core data and I am a bit confused about how to store a part of the object in another entity...
I have only list of location to be inserted to the "Locations" entity and later recently visited place will be stored...
my question is that can I load Locations entity without providing "RecentlySearched" attribute (relationship inverse)
if not how can i do it?
If the relationship is marked as "optional" (which is the default in the Core Data
Model editor) then you don't have to provide a value.
The value of that property will be nil until you establish a relationship to a
"RecentSearch" object.
We would like to create a history table for each of our entities.
Is there a way to have entity framework create the history entities/tables automatically, given the existing entities?
For example, the Customer entity would have a shadow history table called CustomerHistory. Whenever there is an edit or a delete, the old record will be inserted into the history table. The main entity table will always contain the current record.
Since we have several entities, I would rather not have to create a separate history entity and repository for each entity, thus doubling the entities.
We would like to do this for all of our entities in order to track transactional and state temporal changes to the entities.
We use the unit of work and repository patterns.
Assume that the properties of the Entity and the EntityHistory objects would be the same, although we may want to extend the history object with some datetime properties.
I understand how to override DbContext.SaveChanges in order to write to history/audit tables.
What I want to avoid doing is having to create duplicate history entities/repositories for every entity that we have.
I am currently exploring doing something in OnModelCreating to create a history entity for each entity but have not found a good example.
Any ideas?
Before I submit my question, please be aware that I'm working with an existing database owned by a third party vendor, so unfortunately changing the database format is not an option.
Here's the issue: I have an Entity mapped to a database table that has a varchar column that contains one to many foreign keys in csv format. Those foreign keys correspond to the ID's of another Entity type. What I've been doing is writing a function that creates a List of ID's from that csv list and then I search for that Entity through the DBContect object. What I'd like to do is map a relationship between the entities. Is there a way to do that? Thanks!
Unfortunately there is no way to do that without changes in the database. EF is ORM tool but it is still very dependent on correctness of database design. Storing multiple values in single column is breaking even first database normal form. For EF your column containing csv data is single string value and you cannot make relation on that value.
Btw. it is even more complicated because the column cannot represent one-to-many relation in standard relational meaning - that would require dependent entities to contain Id of your master entity, not that master entity contains Ids of all dependent entities.