Replace in-memory examples with Entity Framework Core as requested

Co-authored-by: T-Gro <[email protected]>

Author: Copilot

docs/fsharp/language-reference/query-expressions.md

@@ -16,7 +16,7 @@ query { expression }
 
 ## Remarks
 
-Query expressions are a type of computation expression similar to sequence expressions. Just as you specify a sequence by providing code in a sequence expression, you specify a set of data by providing code in a query expression. In a sequence expression, the `yield` keyword identifies data to be returned as part of the resulting sequence. In query expressions, the `select` keyword performs the same function. In addition to the `select` keyword, F# also supports a number of query operators that are much like the parts of a SQL SELECT statement. Here is an example of a simple query expression using in-memory data.
+Query expressions are a type of computation expression similar to sequence expressions. Just as you specify a sequence by providing code in a sequence expression, you specify a set of data by providing code in a query expression. In a sequence expression, the `yield` keyword identifies data to be returned as part of the resulting sequence. In query expressions, the `select` keyword performs the same function. In addition to the `select` keyword, F# also supports a number of query operators that are much like the parts of a SQL SELECT statement. Here is an example of a simple query expression using Entity Framework Core to query a database.
 
 :::code language="fsharp" source="~/samples/snippets/fsharp/query-expressions/snippet1.fs":::
 
@@ -36,7 +36,7 @@ This table assumes a database in the following form:
 
 ![Diagram that shows a sample database.](./media/query-expressions/student-course-database.png)
 
-The code in the tables that follow also assumes the following database connection code. Projects should add references to System.Linq. The code that creates this database is included at the end of this topic.
+The code in the tables that follow also assumes the following database connection code using Entity Framework Core. Projects should add package references to `Microsoft.EntityFrameworkCore` and `Microsoft.EntityFrameworkCore.InMemory` (or another EF Core provider for production scenarios). This example uses the in-memory database provider for demonstration purposes, but the same query syntax works with any EF Core provider (SQL Server, PostgreSQL, etc.).
 
 :::code language="fsharp" source="~/samples/snippets/fsharp/query-expressions/snippet2.fs":::
 

samples/snippets/fsharp/fssamples.fsproj

@@ -15,7 +15,8 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="FSharp.Data" Version="6.4.0" />
+        <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.0" />
+        <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="9.0.0" />
     </ItemGroup>
 
 </Project>

samples/snippets/fsharp/query-expressions/snippet1.fs

@@ -1,27 +1,42 @@
-// Modern F# query expression example using in-memory data
+// F# query expression example using Entity Framework Core
 open System
 open System.Linq
+open Microsoft.EntityFrameworkCore
 
-// Simple data structures
+// Entity type
+[<CLIMutable>]
 type Customer = {
     CustomerID: int
     CompanyName: string
     ContactName: string
 }
 
-// Sample data
-let customers = [
-    { CustomerID = 1; CompanyName = "Alfreds Futterkiste"; ContactName = "Maria Anders" }
-    { CustomerID = 2; CompanyName = "Ana Trujillo Emparedados y helados"; ContactName = "Ana Trujillo" }
-    { CustomerID = 3; CompanyName = "Antonio Moreno Taquería"; ContactName = "Antonio Moreno" }
-]
+// Database context
+type NorthwindContext() =
+    inherit DbContext()
+    
+    [<DefaultValue>]
+    val mutable private customers: DbSet<Customer>
+    member this.Customers with get() = this.customers and set v = this.customers <- v
+    
+    override _.OnConfiguring(optionsBuilder: DbContextOptionsBuilder) =
+        optionsBuilder.UseInMemoryDatabase("NorthwindDatabase") |> ignore
 
-let db = customers.AsQueryable()
+// Create and seed database
+let db = 
+    let context = new NorthwindContext()
+    context.Customers.AddRange([|
+        { CustomerID = 1; CompanyName = "Alfreds Futterkiste"; ContactName = "Maria Anders" }
+        { CustomerID = 2; CompanyName = "Ana Trujillo Emparedados y helados"; ContactName = "Ana Trujillo" }
+        { CustomerID = 3; CompanyName = "Antonio Moreno Taquería"; ContactName = "Antonio Moreno" }
+    |]) |> ignore
+    context.SaveChanges() |> ignore
+    context
 
 // A query expression
 let query1 =
     query {
-        for customer in db do
+        for customer in db.Customers do
             select customer
     }
 

samples/snippets/fsharp/query-expressions/snippet2.fs

@@ -1,72 +1,97 @@
-// Database setup example for query expressions
+// Database setup example for query expressions using Entity Framework Core
 open System
 open System.Linq
+open Microsoft.EntityFrameworkCore
 
-// Define simple data types to represent our sample database
+// Define entity types that map to database tables
+[<CLIMutable>]
 type Student = {
     StudentID: int
     Name: string
-    Age: int option
+    Age: Nullable<int>
 }
 
+[<CLIMutable>]
 type Course = {
     CourseID: int
     CourseName: string
 }
 
+[<CLIMutable>]
 type CourseSelection = {
     ID: int
     StudentID: int
     CourseID: int
 }
 
-// Sample data
-let students = [
-    { StudentID = 1; Name = "Abercrombie, Kim"; Age = Some 10 }
-    { StudentID = 2; Name = "Abolrous, Hazen"; Age = Some 14 }
-    { StudentID = 3; Name = "Hance, Jim"; Age = Some 12 }
-    { StudentID = 4; Name = "Adams, Terry"; Age = Some 12 }
-    { StudentID = 5; Name = "Hansen, Claus"; Age = Some 11 }
-    { StudentID = 6; Name = "Penor, Lori"; Age = Some 13 }
-    { StudentID = 7; Name = "Perham, Tom"; Age = Some 12 }
-    { StudentID = 8; Name = "Peng, Yun-Feng"; Age = None }
-]
+// Define the database context using Entity Framework Core
+type SchoolContext() =
+    inherit DbContext()
+    
+    [<DefaultValue>]
+    val mutable private student: DbSet<Student>
+    member this.Student with get() = this.student and set v = this.student <- v
+    
+    [<DefaultValue>]
+    val mutable private course: DbSet<Course>
+    member this.Course with get() = this.course and set v = this.course <- v
+    
+    [<DefaultValue>]
+    val mutable private courseSelection: DbSet<CourseSelection>
+    member this.CourseSelection with get() = this.courseSelection and set v = this.courseSelection <- v
+    
+    override _.OnConfiguring(optionsBuilder: DbContextOptionsBuilder) =
+        optionsBuilder.UseInMemoryDatabase("SchoolDatabase") |> ignore
 
-let courses = [
-    { CourseID = 1; CourseName = "Algebra I" }
-    { CourseID = 2; CourseName = "Trigonometry" }
-    { CourseID = 3; CourseName = "Algebra II" }
-    { CourseID = 4; CourseName = "History" }
-    { CourseID = 5; CourseName = "English" }
-    { CourseID = 6; CourseName = "French" }
-    { CourseID = 7; CourseName = "Chinese" }
-]
+// Create and seed the database
+let createAndSeedDatabase() =
+    let context = new SchoolContext()
+    
+    // Seed data
+    context.Student.AddRange([|
+        { StudentID = 1; Name = "Abercrombie, Kim"; Age = Nullable(10) }
+        { StudentID = 2; Name = "Abolrous, Hazen"; Age = Nullable(14) }
+        { StudentID = 3; Name = "Hance, Jim"; Age = Nullable(12) }
+        { StudentID = 4; Name = "Adams, Terry"; Age = Nullable(12) }
+        { StudentID = 5; Name = "Hansen, Claus"; Age = Nullable(11) }
+        { StudentID = 6; Name = "Penor, Lori"; Age = Nullable(13) }
+        { StudentID = 7; Name = "Perham, Tom"; Age = Nullable(12) }
+        { StudentID = 8; Name = "Peng, Yun-Feng"; Age = Nullable() }
+    |]) |> ignore
+    
+    context.Course.AddRange([|
+        { CourseID = 1; CourseName = "Algebra I" }
+        { CourseID = 2; CourseName = "Trigonometry" }
+        { CourseID = 3; CourseName = "Algebra II" }
+        { CourseID = 4; CourseName = "History" }
+        { CourseID = 5; CourseName = "English" }
+        { CourseID = 6; CourseName = "French" }
+        { CourseID = 7; CourseName = "Chinese" }
+    |]) |> ignore
+    
+    context.CourseSelection.AddRange([|
+        { ID = 1; StudentID = 1; CourseID = 2 }
+        { ID = 2; StudentID = 1; CourseID = 3 }
+        { ID = 3; StudentID = 1; CourseID = 5 }
+        { ID = 4; StudentID = 2; CourseID = 2 }
+        { ID = 5; StudentID = 2; CourseID = 5 }
+        { ID = 6; StudentID = 2; CourseID = 6 }
+        { ID = 7; StudentID = 2; CourseID = 3 }
+        { ID = 8; StudentID = 3; CourseID = 2 }
+        { ID = 9; StudentID = 3; CourseID = 1 }
+        { ID = 10; StudentID = 4; CourseID = 2 }
+        { ID = 11; StudentID = 4; CourseID = 5 }
+        { ID = 12; StudentID = 4; CourseID = 2 }
+        { ID = 13; StudentID = 5; CourseID = 3 }
+        { ID = 14; StudentID = 5; CourseID = 2 }
+        { ID = 15; StudentID = 7; CourseID = 3 }
+    |]) |> ignore
+    
+    context.SaveChanges() |> ignore
+    context
 
-let courseSelections = [
-    { ID = 1; StudentID = 1; CourseID = 2 }
-    { ID = 2; StudentID = 1; CourseID = 3 }
-    { ID = 3; StudentID = 1; CourseID = 5 }
-    { ID = 4; StudentID = 2; CourseID = 2 }
-    { ID = 5; StudentID = 2; CourseID = 5 }
-    { ID = 6; StudentID = 2; CourseID = 6 }
-    { ID = 7; StudentID = 2; CourseID = 3 }
-    { ID = 8; StudentID = 3; CourseID = 2 }
-    { ID = 9; StudentID = 3; CourseID = 1 }
-    { ID = 10; StudentID = 4; CourseID = 2 }
-    { ID = 11; StudentID = 4; CourseID = 5 }
-    { ID = 12; StudentID = 4; CourseID = 2 }
-    { ID = 13; StudentID = 5; CourseID = 3 }
-    { ID = 14; StudentID = 5; CourseID = 2 }
-    { ID = 15; StudentID = 7; CourseID = 3 }
-]
-
-// Create a db object that mimics a database context
-type DataContext() =
-    member _.Student = students.AsQueryable()
-    member _.Course = courses.AsQueryable()
-    member _.CourseSelection = courseSelections.AsQueryable()
-
-let db = DataContext()
+// Create the database context
+let db = createAndSeedDatabase()
 
 // Needed for some query operator examples:
 let data = [ 1; 5; 7; 11; 18; 21]