Loopback 4 - Is it possible to define id property's length?

Question

Using LB4 + MySQL DB through loopback-connector-mysql to create tables on DB.

A {id: string, name: string}

id	names
0007bc40-814b-11ec-8128-4df48bd1ae4d	John
0007bc40-814b-11ec-8128-4df48bd1ae3d	Marie

B {id: string, aId:string, name: string}

id	aId	names
0007bc40-814b-11ec-8128-4df48bd1ae2d	0007bc40-814b-11ec-8128-4df48bd1ae4d	Eve
0007bc40-814b-11ec-8128-4df48bd1ae1d	0007bc40-814b-11ec-8128-4df48bd1ae4d	Ronald
0007bc40-814b-11ec-8128-4df48bd1ae0d	0007bc40-814b-11ec-8128-4df48bd1ae3d	Philipe

To create those models, I've used this code:

A

export class Payroll extends Entity {
    @property({
        type: 'string',
        id: true,
        defaultFn: 'uuid',
    })
    id: string;

    
    @property({
        type: 'string',
        required: true,
        length: 64,
    })
    name: string;
}

B

export class Payroll extends Entity {
    @property({
        type: 'string',
        id: true,
        defaultFn: 'uuid',
    })
    id: string;


    @belongsTo(() => A)
    aId: string;
    
    @property({
        type: 'string',
        required: true,
        length: 64,
    })
    name: string;
}

On both tables, id is a VARCHAR(255), although it only needs a VARCHAR(36) On B table, aId is a VARCHAR(512), which is even worse... This could be solved by defining aId as follows:

@belongsTo(() => A, undefined, { length: 36, }) aId: string;

Now, b.aId is a VARCHAR(36), but then i get the error following error:

Error: UNKNOWN_CODE_PLEASE_REPORT: Referencing column 'aId' and referenced column 'id' in foreign key constraint 'fk_a_b_aId' are incompatible", because both VARCHAR have different size.

How can I tell LB4 which length (in this example, 36)of the ID property I want on DB?

Thank you

@RickJames, a constraint could be generated in many ways (for example, with the "required: true"), but it's not clear to me how that relates to my question — Alex Corregidor, Mar 14 '22 at 07:14
@AlexCorregidor i mean that you should shpow us the create table from A and B , because the datatypes seem to be different — nbk, Mar 14 '22 at 12:54
@nbk The CREATE query is generated internally by LB4. The question is how to tell LB4 that I want it to create the ID field with X VARCHAR length. Maybe I've been unclear, I'll edit the question — Alex Corregidor, Mar 14 '22 at 13:19
(Alas, using a framework requires learning two databases -- the underlying db (MySQL) and the framework's rendition of such.) — Rick James, Mar 14 '22 at 16:05

score 0 · Answer 1 · answered Apr 20 '22 at 17:23

0

this works for me.. I prefer to use fixed char guid - old habits ;)

//// For ID (Primary key)
@property({
  type: 'string',
  id: true,
  defaultFn: 'uuidv4',
  dataType: 'char',
  limit: 36,
})
id?: string;

//// for relations
@belongsTo(
  () => RelatedModel,
  {},   // Relation Meta
  {     // Property Meta
    dataType: 'char',
    limit: 36
  }
)
ForeignKeyId: string;

answered Apr 20 '22 at 17:23

Gagan

163
12

This works on "@belongsTo", but on "@property", it keeps creating the id as a VARCHAR(255) on DB – Alex Corregidor Jun 23 '22 at 10:52
@AlexCorregidor, it must be some other issue as this works fine for me.. I am using mysql db with mysql-connector. pls share some of your code if possible. – Gagan Jun 24 '22 at 12:36

Loopback 4 - Is it possible to define id property's length?

1 Answers1