EntityFramework.Seeder

A collection of helper methods to help seed entity framework databases. When seeding your database with lookup entities, we often currently do the following in our Seed methods:

context.Countries.AddOrUpdate(c => c.Code, new Country[]
        {
            new Country{ Code = "CA", Name = "Canada"},
            new Country{ Code = "USA", Name = "United States"}
            //etc...
        });

While this is managable for small amounts of data, our seed methods can become difficult to manage in many real world scenarios.

Using EntiyFramework.Seeder, you can seed your database from CSV files.

First, create a CSV file with column names matching the properties of your entity. In the case of Country, the file would look as follows

Code, Name
CA, Canada
USA, United States
etc...

Next, include the file in project that contains your Seed method and change the Build Action to Embedded Resource.

Finally, call the SeedFromResource extension method:

context.Countries.SeedFromResource("MyProject.SeedData.countries.csv", c => c.Code)

You also have the option to seed from a csv file on disk using SeedFromFile, or from any stream using SeedFromStream.

##Connecting Related Entities Loading data from a CSV file can be a little more complicated when there are relationships between the entities were are loading. Take Countries and Provinces/States as an example. A Province/State always belongs to a single Country. In this case, create a CSV file that includes the Country Code of the Country that the Province State belongs to:

CountryCode,Code,Name
CA,SK,Saskatchewan
CA,AB,Alberta
US,AZ,Arizona
US,AR,Arkansas
US,CA,California

Now, specify a custom mapping action when seeding from the provinces csv:

context.Countries.SeedFromResource("MyProject.SeedData.countries.csv", c => c.Code);
context.SaveChanges();
context.ProvinceStates.SeedFromResource("MyProject.SeedData.provincestates.csv", p => p.Code,
        new CsvColumnMapping<ProvinceState>("CountryCode", (state, countryCode) =>
            {
                state.Country = context.Countries.Single(c => c.Code == countryCode);
            })
         );

##CsvHelper Configuration Under the covers, EntityFramework.Helper uses CsvHelper to read the CSV files. CsvHelper Configuration can be changed by setting properties on the Seeder.Configuration property. For example, to change the delimiter to a | character:

Seeder.Configuration.Delimiter = "|";

All configuration options available in CsvHelper Configuration can be set here. Configuration changes are global and will apply to any Seed methods that are called after a configuration option is changed. If you need to reset to the default configuration, call the Seeder.ResetConfiguration() method.

##Available on Nuget PM> Install-Package EntityFramework.Seeder.EF6