Create a complex Primary Key using Entity Framework code-first

Question

I need to create a complex value via Entity Framework code-first, which includes three the following three values.

A is a constant part look like "s#34"
B is float and it's value come from a API webservice
C is natural number!

I want to C generate automatically . In one example we have these Ids :

+-----+------+--+
|A    |B     |C |
+-----+------+--+
|s#34 |67889 |1 |
|s#34 |68988 |2 |
|s#34 |87665 |3 |
|s#34 |35458 |4 |
|s#34 |..... |5 |
...

I'm looking for a code like this:

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[ID = "string1" + "string2" + default.ToString()]
public int ID { get; set; }

my mean from "default" in code come back to the value that get from (DatabaseGeneratedOption.Identity).

Thank you for your help

Mind showing us what have you tried? Where are you having problem specifically? The `C` value you can generate either via `identity` or `sequence`, `A` you can hardcode in your code meanwhile `B` is just a normal variable you fetch from your webservice. — Rosdi Kasim, Sep 17 '16 at 05:55
my question is about automatic generator! I don't want to check last entity ID in db to create a new row I want to use DataAnnotations abilities look like:"[DatabaseGenerated(DatabaseGeneratedOption)" — Muhammad Ehsan Mirzaei, Sep 18 '16 at 17:51
You could achive this using SQL Server custom identity column... refer here: http://stackoverflow.com/questions/2177584/sqlserver-identity-column-with-text — Rosdi Kasim, Sep 19 '16 at 03:28

score 0 · Accepted Answer · edited May 23 '17 at 10:29

0

Cramming all three pieces of information into one field would violate the single responsibility principle. You should probably create a composite key, and then combine in a computed column if you need to concatenate the three columns for display.

edited May 23 '17 at 10:29

Community

1
1

answered Sep 17 '16 at 03:28

dperish

1,493
16
27

I'm looking for a code like this: [DatabaseGenerated(DatabaseGeneratedOption.Identity)] [ID = "string1" + "string2" + default.ToString()] public int ID { get; set; } my mean from "default" in code come back to the value that get from (DatabaseGeneratedOption.Identity). – Muhammad Ehsan Mirzaei Sep 18 '16 at 19:46

Create a complex Primary Key using Entity Framework code-first

1 Answers1