Faced a error time of migration.

Question

Hello everyone Please help me I want to achieve this task for existing users, but it is not working.This is my code

```

public partial class AddCodePropertiesToUserTable : Migration
{
private readonly DbContext _dbContext;
/// <inheritdoc />
public AddCodePropertiesToUserTable(DbContext dbContext)
{
_dbContext = dbContext;
}
/// <inheritdoc />
protected override void Up(MigrationBuilder migrationBuilder)
{
migrationBuilder.AddColumn<string>(
name: "Code",
table: "User",
type: "text",
nullable: true);

migrationBuilder.AddColumn<string>(
name: "By",
table: "Users",
type: "text",
nullable: true);

migrationBuilder.CreateIndex(
name: "IX_Code",
table: "Users",
column: "Code",
unique: true)
.Annotation("Npgsql:NullsDistinct", true);

migrationBuilder.CreateIndex(
name: "IX_By",
table: "Users",
column: "By");

}
/// <inheritdoc />
protected override void Down(MigrationBuilder migrationBuilder)
{
migrationBuilder.DropIndex(
name: "Code",
table: "Users");

migrationBuilder.DropIndex(
name: "By",
table: "Users");

migrationBuilder.DropColumn(
name: "Code",
table: "Users");

migrationBuilder.DropColumn(
name: "By",
table: "Users");
}
private void UpdateReferralValuesForExistingUser()
{

var usersCode = _dbContext.Users
.Where(u => u.Code == null)
.ToList();

foreach (var user in usersCode)
{
user.Code = GenerateUniqueCode(8);
}
_dbContext.SaveChanges();
//}
}
public string GenerateUniqueCode(int length)
{
if (length < 1)
{
throw new ArgumentException("Length must be greater than 0");
}
Guid guid = Guid.NewGuid();
string base36 = Number.ConvertBase36(guid);
if (base36.Length >= length)
{
return base36.Substring(0, length).ToUpper();
}
else
{
Random random = new Random();
const string chars = "keys";
while (base36.Length < length)
{
base36 += chars[random.Next(chars.Length)];
}
return base36.ToUpper();
}
}
}

private readonly PvrpleShopDbContext _dbContext;
/// <inheritdoc />

private void UpdateReferralValuesForExistingUser()
{
// var factory = new PvrpleShopDbContextFactory();
// using (var context = factory.CreateDbContext(null))
//{
var usersWithoutReferralCode = _dbContext.Users
.Where(u => u.ReferralCode == null)
.ToList();

foreach (var user in usersWithoutReferralCode)
{
user.ReferralCode = GenerateUniqueReferralCode(8);
}

_dbContext.SaveChanges();
//}
}
public string GenerateUniqueReferralCode(int length)
{
if (length < 1)
{
throw new ArgumentException("Length must be greater than 0");
}
Guid guid = Guid.NewGuid();
string base36String = NumberUtilities.ConvertToBase36(guid);
if (base36String.Length >= length)
{
return base36String.Substring(0, length).ToUpper();
}
else
{
Random random = new Random();
const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
while (base36String.Length < length)
{
base36String += chars[random.Next(chars.Length)];
}
return base36String.ToUpper();
}
}

```

Webtual Global · Answer

It looks like you're trying to add and update properties (`Code` and `By`) to an existing `Users` table in your database using Entity Framework Core migrations. There are a few things to check and correct in your migration and code snippet to ensure it works correctly: ### Migration Code 1. **Migration Configuration (`AddCodePropertiesToUserTable`):** - Ensure your migration class inherits from `Migration` or `MigrationBase` provided by Entity Framework Core. - Correct the table name in your migration operations (`"User"` vs `"Users"`). Here’s how you can correct and simplify your migration code: ```csharp public partial class AddCodePropertiesToUserTable : Migration { protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.AddColumn ( name: "Code", table: "Users", // Corrected table name type: "text", nullable: true); migrationBuilder.AddColumn ( name: "By", table: "Users", // Corrected table name type: "text", nullable: true); migrationBuilder.CreateIndex( name: "IX_Code", table: "Users", column: "Code", unique: true); // Ensure this index is correct migrationBuilder.CreateIndex( name: "IX_By", table: "Users", column: "By"); } protected override void Down(MigrationBuilder migrationBuilder) { migrationBuilder.DropIndex( name: "IX_Code", table: "Users"); migrationBuilder.DropIndex( name: "IX_By", table: "Users"); migrationBuilder.DropColumn( name: "Code", table: "Users"); migrationBuilder.DropColumn( name: "By", table: "Users"); } } ``` 2. **Ensure Index Naming:** - Ensure that index names (`IX_Code`, `IX_By`) correspond correctly to the columns they are indexing. ### Code to Update Existing Users 1. **DbContext and Dependency Injection:** - Ensure `_dbContext` is correctly injected into your migration class or wherever `UpdateReferralValuesForExistingUser` method is located. ```csharp private readonly DbContext _dbContext; public AddCodePropertiesToUserTable(DbContext dbContext) { _dbContext = dbContext; } ``` 2. **Update Existing Users Method:** - Call `UpdateReferralValuesForExistingUser` method in your migration to update existing users with generated codes. ```csharp protected override void Up(MigrationBuilder migrationBuilder) { // Add columns and indices as shown above // Update existing users with referral codes UpdateReferralValuesForExistingUser(); } private void UpdateReferralValuesForExistingUser() { var usersWithoutReferralCode = _dbContext.Set () .Where(u => u.ReferralCode == null) .ToList(); foreach (var user in usersWithoutReferralCode) { user.ReferralCode = GenerateUniqueReferralCode(8); } _dbContext.SaveChanges(); } ``` ### GenerateUniqueReferralCode Method Ensure your `GenerateUniqueReferralCode` method is correctly generating unique referral codes: ```csharp public string GenerateUniqueReferralCode(int length) { if (length { throw new ArgumentException("Length must be greater than 0"); } Guid guid = Guid.NewGuid(); string base36String = NumberUtilities.ConvertToBase36(guid); if (base36String.Length >= length) { return base36String.Substring(0, length).ToUpper(); } else { Random random = new Random(); const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; while (base36String.Length { base36String += chars[random.Next(chars.Length)]; } return base36String.ToUpper(); } } ``` ### Notes - **Dependency Injection**: Ensure that `_dbContext` is correctly injected into your migration or class where the update method resides. - **Migration Execution**: After correcting the migration code and ensuring `_dbContext` is properly set up, run `dotnet ef database update` or use the appropriate tooling to apply the migration to your database. By following these steps, you should be able to add the `Code` and `By` properties to your `Users` table and update existing users with generated codes successfully. Adjust the specifics based on your actual DbContext and entity configurations as needed.