With the type aliases for DB objects set up, we can move forward to creating our first queries in Db module:


let getGenres (ctx : DbContext) : Genre list = ctx.Public.Genres |> Seq.toList

getGenres is a function for finding all genres. The function, as well as all functions we'll define in Db module, takes the DbContext as a parameter. The : Genre list part is a type annotation, which makes sure the function returns a list of Genres. Implementation is straight forward: Using dot notation we can access all genres, and then just pipe it to Seq.toList to match the expected return type.


let getAlbumsForGenre genreName (ctx : DbContext) : Album list = query { for album in ctx.Public.Albums do join genre in ctx.Public.Genres on (album.Genreid = genre.Genreid) where (genre.Name = genreName) select album } |> Seq.toList

getAlbumsForGenre takes genreName as argument (inferred to be of type string) and returns a list of Albums. It makes use of "query expression" (query { }) which is very similar to C# Linq query. Read here for more info about query expressions. Inside the query expression, we're performing an inner join of Albums and Genres with the GenreId foreign key, and then we apply a predicate on genre.Name to match the input genreName. The result of the query is piped to Seq.toList.


let getAlbumDetails id (ctx : DbContext) : AlbumDetails option = query { for album in ctx.Public.Albumdetails do where (album.Albumid = id) select album } |> Seq.tryHead

getAlbumDetails takes id as argument (inferred to be of type int) and returns AlbumDetails option because there might be no Album with the given id. Here, the result of the query is piped to the Seq.tryHead function, which takes care to transform the result to option type. Seq.tryHead verifies if a query returned any result: If the sequence contains any element Seq.tryHead returns Some, otherwise None.

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namespace FSharp

namespace Microsoft.FSharp
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namespace FSharp.Data

namespace Microsoft.FSharp.Data
namespace FSharp.Data.Sql
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type LiteralAttribute =
inherit Attribute
new : unit -> LiteralAttribute

Full name: Microsoft.FSharp.Core.LiteralAttribute

new : unit -> LiteralAttribute
val ConnectionString : string

Full name: SuaveMusicStore.Db.ConnectionString
type Sql = SqlDataProvider<...>

Full name: SuaveMusicStore.Db.Sql
type SqlDataProvider

Full name: FSharp.Data.Sql.SqlDataProvider

<summary>Typed representation of a database</summary>
<param name='ConnectionString'>The connection string for the SQL database</param>
<param name='ConnectionStringName'>The connection string name to select from a configuration file</param>
<param name='DatabaseVendor'> The target database vendor</param>
<param name='IndividualsAmount'>The amount of sample entities to project into the type system for each SQL entity type. Default 1000.</param>
<param name='UseOptionTypes'>If true, F# option types will be used in place of nullable database columns. If false, you will always receive the default value of the column's type even if it is null in the database.</param>
<param name='ResolutionPath'>The location to look for dynamically loaded assemblies containing database vendor specific connections and custom types.</param>
<param name='Owner'>The owner of the schema for this provider to resolve (Oracle Only)</param>
<param name='CaseSensitivityChange'>Should we do ToUpper or ToLower when generating table names?</param>
<param name='TableNames'>Comma separated table names list to limit a number of tables in big instances. The names can have '%' sign to handle it as in the 'LIKE' query (Oracle and MSSQL Only)</param>
<param name='OdbcQuote'>Odbc quote characters: Quote characters for the table and column names: `alias`, [alias]</param>
<param name='SQLiteLibrary'>Use System.Data.SQLite or Mono.Data.SQLite or select automatically (SQLite only)</param>
namespace FSharp.Data.Sql.Common
type DatabaseProviderTypes =
| SQLITE = 1
| MYSQL = 3
| ORACLE = 4
| ODBC = 6

Full name: FSharp.Data.Sql.Common.DatabaseProviderTypes
Common.DatabaseProviderTypes.POSTGRESQL: Common.DatabaseProviderTypes = 2
type CaseSensitivityChange =

Full name: FSharp.Data.Sql.Common.CaseSensitivityChange
Common.CaseSensitivityChange.ORIGINAL: Common.CaseSensitivityChange = 0
type DbContext = SqlDataProvider<...>.dataContext

Full name: SuaveMusicStore.Db.DbContext
type dataContext =
member ClearUpdates : unit -> List<SqlEntity>
member CreateConnection : unit -> IDbConnection
member GetUpdates : unit -> List<SqlEntity>
member Public : publicSchema
member SubmitUpdates : unit -> Unit
member SubmitUpdatesAsync : unit -> Async<Unit>
nested type public.albumdetails.Individuals
nested type public.albumdetailsEntity
nested type public.albums.Individuals
nested type public.albumsEntity

Full name: FSharp.Data.Sql.SqlDataProvider,DatabaseVendor="2",ConnectionString="Server=;Database=suavemusicstore;User Id=suave;Password=1234;",CaseSensitivityChange="0".dataContext
type Album = SqlDataProvider<...>.dataContext.public.albumsEntity

Full name: SuaveMusicStore.Db.Album
type Genre = SqlDataProvider<...>.dataContext.public.genresEntity

Full name: SuaveMusicStore.Db.Genre
type AlbumDetails = SqlDataProvider<...>.dataContext.public.albumdetailsEntity

Full name: SuaveMusicStore.Db.AlbumDetails
val getGenres : ctx:DbContext -> Genre list

Full name: SuaveMusicStore.Db.getGenres
val ctx : DbContext
type 'T list = List<'T>

Full name: Microsoft.FSharp.Collections.list<_>
property SqlDataProvider<...>.dataContext.Public: SqlDataProvider<...>.dataContext.publicSchema
property SqlDataProvider<...>.dataContext.publicSchema.Genres: SqlDataProvider<...>.dataContext.publicSchema.public.genres

<summary> The base table genres belonging to schema public</summary>
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module Seq

from FSharp.Data.Sql

module Seq

from Microsoft.FSharp.Collections
val toList : source:seq<'T> -> 'T list

Full name: Microsoft.FSharp.Collections.Seq.toList
val getAlbumsForGenre : genreName:string -> ctx:DbContext -> Album list

Full name: SuaveMusicStore.Db.getAlbumsForGenre
val genreName : string
val query : Linq.QueryBuilder

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.query
val album : SqlDataProvider<...>.dataContext.public.albumsEntity
property SqlDataProvider<...>.dataContext.publicSchema.Albums: SqlDataProvider<...>.dataContext.publicSchema.public.albums

<summary> The base table albums belonging to schema public</summary>
custom operation: join var in collection on (outerKey = innerKey). Note that parentheses are required after 'on'

Calls Linq.QueryBuilder.Join
val genre : SqlDataProvider<...>.dataContext.public.genresEntity
property SqlDataProvider<...>.dataContext.public.genresEntity.Genreid: int

<summary> integer</summary>
custom operation: where (bool)

Calls Linq.QueryBuilder.Where
property SqlDataProvider<...>.dataContext.public.genresEntity.Name: string

<summary> character varying(120)</summary>
custom operation: select ('Result)

Calls Linq.QueryBuilder.Select
val getAlbumDetails : id:int -> ctx:DbContext -> AlbumDetails option

Full name: SuaveMusicStore.Db.getAlbumDetails
val id : int
type 'T option = Option<'T>

Full name: Microsoft.FSharp.Core.option<_>
val album : SqlDataProvider<...>.dataContext.public.albumdetailsEntity
property SqlDataProvider<...>.dataContext.publicSchema.Albumdetails: SqlDataProvider<...>.dataContext.publicSchema.public.albumdetails

<summary> The view albumdetails belonging to schema public</summary>
property SqlDataProvider<...>.dataContext.public.albumdetailsEntity.Albumid: int

<summary> integer</summary>
val tryHead : source:seq<'T> -> 'T option

Full name: Microsoft.FSharp.Collections.Seq.tryHead
type IntPath = PrintfFormat<(int -> string),unit,string,string,int>

Full name: SuaveMusicStore.Path.IntPath
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type PrintfFormat<'Printer,'State,'Residue,'Result> =
new : value:string -> PrintfFormat<'Printer,'State,'Residue,'Result>
member Value : string

Full name: Microsoft.FSharp.Core.PrintfFormat<_,_,_,_>

type PrintfFormat<'Printer,'State,'Residue,'Result,'Tuple> =
inherit PrintfFormat<'Printer,'State,'Residue,'Result>
new : value:string -> PrintfFormat<'Printer,'State,'Residue,'Result,'Tuple>

Full name: Microsoft.FSharp.Core.PrintfFormat<_,_,_,_,_>

new : value:string -> PrintfFormat<'Printer,'State,'Residue,'Result>

new : value:string -> PrintfFormat<'Printer,'State,'Residue,'Result,'Tuple>
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val int : value:'T -> int (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.int

type int = int32

Full name: Microsoft.FSharp.Core.int

type int<'Measure> = int

Full name: Microsoft.FSharp.Core.int<_>
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val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

type string = System.String

Full name: Microsoft.FSharp.Core.string
type unit = Unit

Full name: Microsoft.FSharp.Core.unit
val withParam : key:string * value:string -> path:string -> string

Full name: SuaveMusicStore.Path.withParam
val key : string
val value : string
val path : string
val sprintf : format:Printf.StringFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.sprintf
val home : string

Full name: SuaveMusicStore.Path.home
module Store

from SuaveMusicStore.Path
val overview : string

Full name: SuaveMusicStore.Path.Store.overview
val browse : string

Full name: SuaveMusicStore.Path.Store.browse
val details : IntPath

Full name: SuaveMusicStore.Path.Store.details
val browseKey : string

Full name: SuaveMusicStore.Path.Store.browseKey
namespace Suave
module Html

from Suave
val cssLink : href:string -> Node

Full name: SuaveMusicStore.View.cssLink
val href : string
val link : attr:Attribute list -> Node

Full name: Suave.Html.link
val h2 : s:string -> Node

Full name: SuaveMusicStore.View.h2
val s : string
val tag : tag:string -> attr:Attribute list -> contents:Node list -> Node

Full name: Suave.Html.tag
union case Node.Text: string -> Node
val ul : nodes:Node list -> Node

Full name: SuaveMusicStore.View.ul
val nodes : Node list
val li : (Node list -> Node)

Full name: SuaveMusicStore.View.li
val home : Node list

Full name: SuaveMusicStore.View.home
val store : genres:string list -> Node list

Full name: SuaveMusicStore.View.store
val genres : string list
val p : (Attribute list -> Node list -> Node)

Full name: Suave.Html.p
Multiple items
module List

from Microsoft.FSharp.Collections

type List<'T> =
| ( [] )
| ( :: ) of Head: 'T * Tail: 'T list
interface IEnumerable
interface IEnumerable<'T>
member GetSlice : startIndex:int option * endIndex:int option -> 'T list
member Head : 'T
member IsEmpty : bool
member Item : index:int -> 'T with get
member Length : int
member Tail : 'T list
static member Cons : head:'T * tail:'T list -> 'T list
static member Empty : 'T list

Full name: Microsoft.FSharp.Collections.List<_>
val length : list:'T list -> int

Full name: Microsoft.FSharp.Collections.List.length
val genre : string
val url : string
module Path

from SuaveMusicStore
val a : href:string -> attr:Attribute list -> (Node list -> Node)

Full name: Suave.Html.a
val browse : genre:string -> Node list

Full name: SuaveMusicStore.View.browse
val details : id:int -> Node list

Full name: SuaveMusicStore.View.details
val index : container:Node list -> string

Full name: SuaveMusicStore.View.index
val container : Node list
val html : (Attribute list -> Node list -> Node)

Full name: Suave.Html.html
val head : (Attribute list -> Node list -> Node)

Full name: Suave.Html.head
val title : attr:Attribute list -> s:string -> Node

Full name: Suave.Html.title
val body : (Attribute list -> Node list -> Node)

Full name: Suave.Html.body
val div : (Attribute list -> Node list -> Node)

Full name: Suave.Html.div
val htmlToString : node:Node -> string

Full name: Suave.Html.htmlToString
module App

from SuaveMusicStore
module Filters

from Suave
module Operators

from Suave
module RequestErrors

from Suave
module Successful

from Suave
module Web

from Suave
val html : container:Html.Node list -> WebPart

Full name: SuaveMusicStore.App.html
val container : Html.Node list
val OK : body:string -> WebPart

Full name: Suave.Successful.OK
module View

from SuaveMusicStore
val index : container:Html.Node list -> string

Full name: SuaveMusicStore.View.index
val browse : (HttpContext -> Async<HttpContext option>)

Full name: SuaveMusicStore.App.browse
val request : apply:(HttpRequest -> HttpContext -> 'a) -> context:HttpContext -> 'a

Full name: Suave.Http.request
val r : HttpRequest
member HttpRequest.queryParam : key:string -> Choice<string,string>
union case Choice.Choice1Of2: 'T1 -> Choice<'T1,'T2>
val browse : genre:string -> Html.Node list

Full name: SuaveMusicStore.View.browse
union case Choice.Choice2Of2: 'T2 -> Choice<'T1,'T2>
val msg : string
val BAD_REQUEST : body:string -> WebPart

Full name: Suave.RequestErrors.BAD_REQUEST
val webPart : WebPart<HttpContext>

Full name: SuaveMusicStore.App.webPart
val choose : options:WebPart<'a> list -> WebPart<'a>

Full name: Suave.WebPart.choose
val path : pathAfterDomain:string -> WebPart

Full name: Suave.Filters.path
val home : Html.Node list

Full name: SuaveMusicStore.View.home
val store : genres:string list -> Html.Node list

Full name: SuaveMusicStore.View.store
val pathScan : pf:PrintfFormat<'a,'b,'c,'d,'t> -> h:('t -> WebPart) -> WebPart

Full name: Suave.Filters.pathScan
val details : Path.IntPath

Full name: SuaveMusicStore.Path.Store.details
val details : id:int -> Html.Node list

Full name: SuaveMusicStore.View.details
val pathRegex : pathAfterDomainRegex:string -> WebPart

Full name: Suave.Filters.pathRegex
module Files

from Suave
val browseHome : WebPart

Full name: Suave.Files.browseHome
val startWebServer : config:SuaveConfig -> webpart:WebPart -> unit

Full name: Suave.Web.startWebServer
val defaultConfig : SuaveConfig

Full name: Suave.Web.defaultConfig

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