What is hasMany?

What is hasMany?

One to many(hasMany): A user has many(can have many) article. So, Many article belongs to one user; Many to many(BelongsToMany): A User can belongs to many forum. So, A forum belongs to many user.

What is an example of a polymorphic lookup field in Salesforce pd1?

Salesforce makes use of polymorphic relationship fields for native lookup fields that can reference multiple objects. The most common fields that use polymorphic relationships are Owner fields and Activity WhatId/WhoId fields.

What is polymorphic association in Rails?

In Ruby on Rails, a polymorphic association is an Active Record association that can connect a model to multiple other models. For example, we can use a single association to connect the Review model with the Event and Restaurant models, allowing us to connect a review with either an event or a restaurant.

What is morph relationship?

Polymorphic relations allow a model to belong to more than one other model on a single association. For example, imagine users of your application can “like” both posts and comments. Using polymorphic relationships, you can use a single likes table for both of these scenarios.

What is belongsToMany relationship?

As a rule of thumb, if you use a belongsToMany relationship, it can only be paired with another belongsToMany relationship and means that you have a third pivot table. If you use a hasMany relationship, it can only be paired with a belongsTo relationship and no extra database tables are required.

What is an example of many relationships?

A many-to-many relationship occurs when multiple records in a table are associated with multiple records in another table. For example, a many-to-many relationship exists between customers and products: customers can purchase various products, and products can be purchased by many customers.

Which exception Cannot be caught in Salesforce?

Exceptions that Can’t be Caught One such exception is the limit exception ( System. LimitException ) that the runtime throws if a governor limit has been exceeded, such as when the maximum number of SOQL queries issued has been exceeded.

What is polymorphism in Salesforce?

Polymorphism in Apex requires an Apex Interface to be implemented or Class that can be extended by other Apex classes e.g. Virtual or Abstract classes. The implementing or extending classes can then be used in a predictable, consistent way even though their types are different from one another.

When to use typeof in a polymorphic query?

TYPEOF is only allowed in the SELECT clause of a query. You can filter on the object type of a polymorphic relationship using the Type qualifier in a WHERE clause, see Filtering on Polymorphic Relationship Fields for more details.

How are relationship fields used in a polymorphic relationship?

In a polymorphic relationship, the referenced object of the relationship can be one of several different types of object. Some fields are relationship fields, which means they can be used to get information about a related object. And some of those relationship fields are polymorphic fields.

How to use polymorphic fields in soql queries?

If you want more general information on polymorphic relationships, see Understanding Relationship Fields and Polymorphic Fields in the SOQL and SOSL Reference. You can use SOQL queries that reference polymorphic fields in Apex to get results that depend on the object type referenced by the polymorphic field.

What are new features for querying polymorphic relations in Laravel?

The Laravel team released v5.8.27 with a whereHasMorph () method to work with polymorphic Eloquent relationships ( MorphTo ). The new whereHasMorph () and corresponding methods make it possible to query polymorphic relationships with something like the following: Which produces something like the following query: