I'm developing a new application which is based on a legacy database. The old legacy database does not use reference integrity and first we try to not change the existing schema. I still want to be be able to use navigation properties in my EF generated POCO classes.
However, the old data model has one big issue regarding child-parent relationships: the column in the child table is referencing the parent table via the uniqe key of the parent, not via the primary key of the parent table. Is it still possible to generate such associations?
I tried to mark the unique key in the parent table as "entity key" but then I still need to provide a mapping for the parent table's primary key which I am not able to because there is no mapping for it available, this primary is just a dummy "counter". If I do not provide a mapping for the primary key, I get
"Error 111: Properties referred by the Principal Role XXX must be exactly identical to the key of the EntityType YYY referred to by the Principal Role in the relationship constraint for Relationship ZZZ. Make sure all the key properties are specified in the Principal Role"
No EF does not support unique keys at all. It is hopefully planned feature of the next major release.
Related
Is it possible to have a OneToManyAssociationField as entity extension on for example ProductManufacturer without the ReferenceVersionField in my related custom entity?
If this is not possible, is it possible for the reference version field to have a custom name (so not product_manufacturer_version_id) On first sight, this also does not seem possible.
About the error
I am currently getting the following error when trying to search for manufacturers using $criteria->addAssociation('myCustomEntity'):
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'product_manufacturer.myCustomEntity.product_manufacturer_version_id' in 'field list'
About the big picture
The use case is similar to the SeoUrl entity where there is a ‘foreign_key’ field which can have a relation to multiple entity types. My entity has not associations, but the other entities are extended to have an association to my entity. Just like the SeoUrl.
However, the DAL creates a query which uses the ‘product_manufacturer_version_id’ field, which does not exist on my custom entity…
Is it possible to have a OneToManyAssociationField as entity extension on for example ProductManufacturer without the ReferenceVersionField in my related custom entity?
No, you must set a ReferenceVersionField when adding associations to the definition of a versionized entity. This is too deeply rooted in the basic principles of the data abstraction layer to work around.
If this is not possible, is it possible for the reference version field to have a custom name (so not product_manufacturer_version_id) On first sight, this also does not seem possible.
You can change the storage name of the field. That is the name of the corresponding column within your database table. When you instantiate ReferenceVersionField you can use the second, optional argument to provide the storage name:
public function __construct(string $definition, ?string $storageName = null)
The storage name should be provided in snake case. The name of the object property for the field will then be derived from the storage name and converted to camel case. So given you provide my_version_custom_id for the storage name, the object property of the entity will be myVersionCustomId.
Your entity may have multiple associations to different entities, but if those entities are versionized your foreign key constraint has to be a combination of columns for both the foreign primary key as well as the foreign version id.
I have a table structure where a foreign key from Employee table references something other than the primary key of the Department table. This is for historical reasons, so that's just the way it is.
This works: q.Join<Department>((e, d) => e.DepartmentId == d.DepNo);. Note that Department's primary key is Id.
Now, is there any way I could specify the join relationship (with the column name)? The reason is that I'd like to use AutoQuery's built-in IJoin<Employee,Department> thing, but that doesn't let me specify the columns to use.
Please see docs on Reference Conventions for how to define implicit PK and FK references.
AutoQuery only supports implicit references, if you need more customized behavior you’ll need to create a custom AutoQuery implementation.
I am working on Azure and I have created a database with Cosmos DB SQL API. After creating a container I see that the primary key is always named "id". Is there any way to create a container with PK with name different than "id"?
Every document has a unique id called id. This cannot be altered. If you don't set a value, it is assigned a GUID.
When using methods such as ReadDocument() (or equivalent, based on the SDK) for direct reads instead of queries, a document's id property must be specified.
Now, as far as partitioning goes, you can choose any property you want to use as the partition key.
And if you have additional domain-specific identifiers (maybe a part number), you can always store those in their own properties as well. In this example though, just remember that, while you can query for documents containing a specific part number, you can only do a direct-read via id. If direct reads will be the majority of your read operations, then it's worth considering the use of id to store such a value.
PK = primary key, by the way ;) It's the "main" key for the record, it is not private :)
And no, as far as I know you cannot change the primary key name. It is always "id". Specifically it must be in lowercase, "Id" is not accepted.
When I tried to retrieve table using contains keyword it prompts "Cannot use CONTAINS relation on non collection column col1" but when I tried to create table using
CREATE TABLE test (id int,address map<text, int>,mail list<text>,phone set<int>,primary key (id,address,mail,phone));
it prompts "Invalid collection type for PRIMARY KEY component phone"
One of the basics in Cassandra is that you can't modify primary keys. Always keep that in mind.
You can't use a collection as primary key unless it is frozen, meaning you can't modify it.
This will work
CREATE TABLE test (id int,address frozen<map<text, int>>,mail frozen<list<text>>,phone frozen<set<int>>,primary key (id,address,mail,phone));;
However, I think you should take a look at this document: http://www.datastax.com/dev/blog/cql-in-2-1
You can put secondary indexes on collections after cql 2.1. You may want to use that functionality.
I'm working with Liferay. When create an entity, we define one column as the primary key. Then I look at the entity model, I see some methods setPrimaryKey, getPrimaryKey as well as the setter and getter of the column that we defined as the primary key before. What is the difference of these methods? Do we need to use both methods once we add new entity into the table or just one
Assuming that your project is built by many people. Some one designs entity and you only code view page. When you want to get or set primary key of entity but you don't know what column. If don't have setPrimaryKey or getPrimaryKey methods, do you look up in the code to find what column is primary key?