How to prevent duplicate entities in many-to-many table with Angular
How can I prevent duplication of records with the same combinations of entities, here : id_product and id_customer. When I click "save relation" a relation (many-to-many) between product and customer is created and this relation has its own id, id_product and id_customer. Is there any solution to block creation of relation between product and customer if such combination already exists in MySQL database ?
public saveRelation = (relationFormValue) => { const newRelation = { id_product: relationFormValue.id_product , id_customer: relationFormValue.id_customer }; const dialogRef = this.dialog.open(ConfirmDialogComponent, { maxWidth: "400px", data: new ConfirmDialogModel("Please confirm",'Are you sure to save this relation ?') }); dialogRef.afterClosed().subscribe(dialogResult => { if (dialogResult==true) { this.relationService.create(newRelation) .subscribe( response => { this.dialogRef.close(true); }, error => { this.errorService.handleError(error); }); } }); }
