How to add update child entities when updating a parent entity in ef?

How to add/update child entities when updating a parent entity in…

1. Get a tracked parent entity named existing by model.Id , and assign values in model one by one to the entity. This sounds stupid.
2. Create a new parent entity via model , and attached it to the DbContext and save it.

What is include in EF?

The Entity Framework Core (EF) extension method Include provides us the ability to load additional data besides the entities we are querying for. For example: loading products along with their translations. var products = Context. Products . Include(p => p.

What is parent table in database?

Child tables and parent tables are just normal database tables, but they’re linked in a way that’s described by a parent–child relationship. It’s usually used to specify where one table’s value refers to the value in another table (usually a primary key of another table).

How do I update DTO?

Updating entity from DTO without fetching it

1. Fetch data into DTO.
2. Change the DTO.
3. Create stub entity from the DTO – basically just ID and changed values (this is where some automapper-like libraries help a lot).
4. Update the entity (only the changed values, of course) using regular SaveChanges .

What is lazy loading EF?

Lazy loading is delaying the loading of related data, until you specifically request for it. It is the opposite of eager loading. In the lazy loading, the context first loads the Student entity data from the database, then it will load the StudentAddress entity when we access the StudentAddress property as shown below.

Can a parent table have multiple child tables?

A parent-child relationship between two tables can be created only when there is a PRIMARY KEY in one table and FOREIGN KEY in another table. …

What is a parent and child table?

How to add parent record with its children Records in EF Core?

Entity Parent P has children C1, and C2 in a one-to-one relationship. Trying to insert a parent and its children records. But in the following code VS2017 ‘s editor’s intellisense does not recognize .child at the line cust.child.Add (c1);. Maybe, EF Core has something better for inserting parent/child records.

How to add / update child in Entity Framework?

(Unless you would track the changes with your own tracking mechanism during the detached state (in the browser or wherever) which in my opinion is more complex than the following.) It could look like this: …CurrentValues.SetValues can take any object and maps property values to the attached entity based on the property name.

Is there an INSERT statement in EF Core?

EDITRemoving that call to SaveChanges changes nothing. Also, I couldn’t find any INSERT orUPDATE SQL statement generated by EF when watching what happens in SQL Server Profiler. EDIT2The INSERT statement is there when SaveChanges is called, but still there is no UPDATE statement for Master entity.

How to make example 2 below work in EF Core?

Example 1 below used to work but it is not working in EF Core. Question: How to make example 2 below work? Entity Parent P has children C1, and C2 in a one-to-one relationship.

How to add update Child entities when updating a parent entity in EF?

How to add/update child entities when updating a parent entity in…

1. Get a tracked parent entity named existing by model.Id , and assign values in model one by one to the entity. This sounds stupid.
2. Create a new parent entity via model , and attached it to the DbContext and save it.

How do you add parent record with children’s records in EF core?

How to add a parent record with its children records in EF Core

1. Example 1: child c1 = new child(); child c2 = new child(); parent p=new parent(); p.child.Add(c1); p.child.Add(c2); using (var db = new DbContext()) { db.parent.Add(p); db.SaveChanges(); }
2. Example 2:
3. UPDATE:

Can an entity have more than one parent?

This model would probably work fine, as long as an entity could never have more than one parent. I need to be able to allow an entity to have more than one parent. Yes, two entities could be related to one another in two or more different types of relationships.

How do you add entities?

Project -> Add New Item…

1. Project -> Add New Item…
2. Select Data from the left menu and then ADO.NET Entity Data Model.
3. Enter BloggingModel as the name and click OK.
4. This launches the Entity Data Model Wizard.
5. Select Generate from Database and click Next.

What is attach in Entity Framework?

Attach is used to repopulate a context with an entity that is known to already exist in the database. SaveChanges will therefore not attempt to insert an attached entity into the database because it is assumed to already be there.

What is entry in Entity Framework?

Entry(Object) The entry provides access to change tracking information and operations for the entity. This method may be called on an entity that is not tracked. You can then set the State property on the returned entry to have the context begin tracking the entity in the specified state.

What is the relationship between a parent entity and a child entity?

The entity types associated through a relationship fulfill two roles: One entity is a parent entity. The second entity is a child entity. The parent entity shares it identity with the child entity. The child entity inherits the primary key of the parent entity type and is referred to as a dependent entity type.

Can a child table have two parent tables?

It depends. In general, you would like to have foreign key relationships. If there is only one comment allowed per question/answer, then it is easy. A commentId goes in each of the tables, Questions and Answers .

What is Entity Developer?

Entity Developer is a powerful ORM designer for ADO.NET Entity Framework, Entity Framework Core, NHibernate, LinqConnect, Telerik Data Access, and LINQ to SQL. It introduces new approaches for designing ORM models, boosts productivity, and facilitates the development of database applications.

What is attach method?

Use the Attach methods with entities that have been created in one DataContext, serialized to a client, and then deserialized back to perform an update or delete operation. After calling this method, you can then update its fields, for example with additional data sent from the client.

What is detach in entity Framework?

Removes the object from the ObjectStateManager. This disables change tracking and identity resolution for that object. Detach only affects the specific object that is passed to the method. If the object being detached has related objects in the object context, those objects are not detached.

How to add / update child entities when updating a..?

Get a tracked parent entity named existing by model.Id, and assign values in model one by one to the entity. This sounds stupid. And in model.Children I don’t know which child is new, which child is modified (or even deleted). Create a new parent entity via model, and attached it to the DbContext and save it.

Can you add a parent and two children at the same time?

I have run into the same identity “limitation” as well. It turns out that if you add a parent and any children, EF can handle the fact that the parent and children are all being added together. You run into problems when you Update the parent and insert two children at the same time.

How do you update an entity in entityframeworkcore?

If you are using EntityFrameworkCore you can do the following in your controller post action (The Attach method recursively attaches navigation properties including collections): It is assumed that each entity that was updated has all properties set and provided in the post data from the client (eg. won’t work for partial update of an entity).

Can a child have the same primary key as the parent?

However, EF cannot handle items with the same Primary key when the parent is an Update and blows up since both have the same PK of 0 for both children. The only way I have found around this is to manually set the ids of the children to different numbers. I usually set the first child’s Id to -1, then -2 for the second child, and so on.