.Net Core Seed Database from Json Files - asp.net-core

Question

I've been searching ways to seed data on a .Net Core 3.1 MVC app. I've found many samples, starting from the documentation. What I haven't found was good, real-life full-examples using (Json/XML) file. The closest one I found doesn't show how to properly get a (Json/XML) file's location no matter the platform used. I haven't been able to successfully integrate DI solutions found on other stack overflow questions makes me think it's not possible. Hoping someone can help.
Thanks!

Answer 1

The closest one I found doesn't show how to properly get a (Json/XML) file's location no matter the platform used.
If your json file exists in the physical disks,you just use the original physical location:
using (StreamReader r = new StreamReader(#"C:\xxx\xxx\test.json"))
If your json file exists in the project and in the root project,use the following location:
using (StreamReader r = new StreamReader(#"test.json"))
If it exists in the folders in the project,you could use the location like below:
using (StreamReader r = new StreamReader(#"wwwroot/test.json"))
And another thing you need to know,althogh you have multiple models with relationships,be sure the json should contain only one model's data.
Here is a example code:
1.Model:
public class Test
{
public int Id { get; set; }
public string Name { get; set; }
public int UserId { get; set; }
public List<User> User { get; set; }
}
public class User
{
public int Id { get; set; }
public int Age { get; set; }
}
2.DbContext:
public class YourDbContext : DbContext
{
public YourDbContext(DbContextOptions<YourDbContext> options)
: base(options)
{
}
public DbSet<Test> Test { get; set; }
public DbSet<User> User { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Test>().HasData(SeedTestData());
}
public List<Test> SeedTestData()
{
var tests = new List<Test>();
using (StreamReader r = new StreamReader(#"test.json"))
{
string json = r.ReadToEnd();
tests = JsonConvert.DeserializeObject<List<Test>>(json);
}
return tests;
}
public List<User> SeedUserData()
{
var users = new List<User>();
using (StreamReader r = new StreamReader(#"test2.json"))
{
string json = r.ReadToEnd();
users = JsonConvert.DeserializeObject<List<User>>(json);
}
return users;
}
}
3.Run following command in Package Manager Console:
>PM Add-Migration init
>PM Update-Database
test.json:
[
{
"id": 1,
"name": "aa"
},
{
"id": 2,
"name": "bb"
},
{
"id": 3,
"name": "cc"
}
]
test2.json:
[
{
"id": 1,
"age": 34
},
{
"id": 2,
"age": 21
}
]