Copyright	(c) digitally induced GmbH 2020
Safe Haskell	None
Language	GHC2021

IHP.QueryBuilder.Union

Description

This module provides functions for combining queries with UNION and OR operations.

Synopsis

queryUnion :: forall (model :: Symbol). QueryBuilder model -> QueryBuilder model -> QueryBuilder model
queryUnionList :: forall (table :: Symbol). (Table (GetModelByTableName table), KnownSymbol table, GetTableName (GetModelByTableName table) ~ table) => [QueryBuilder table] -> QueryBuilder table
queryOr :: forall (model :: Symbol). (QueryBuilder model -> QueryBuilder model) -> (QueryBuilder model -> QueryBuilder model) -> QueryBuilder model -> QueryBuilder model

Documentation

queryUnion :: forall (model :: Symbol). QueryBuilder model -> QueryBuilder model -> QueryBuilder model Source #

Merges the results of two query builders by ORing their WHERE conditions.

Take a look at queryOr as well, as this might be a bit shorter.

Example: Return all pages owned by the user or owned by the users team.

let userPages = query @Page |> filterWhere (#ownerId, currentUserId)
let teamPages = query @Page |> filterWhere (#teamId, currentTeamId)
pages <- queryUnion userPages teamPages |> fetch
-- SELECT * FROM pages WHERE (owner_id = '..') OR (team_id = '..')

queryUnionList :: forall (table :: Symbol). (Table (GetModelByTableName table), KnownSymbol table, GetTableName (GetModelByTableName table) ~ table) => [QueryBuilder table] -> QueryBuilder table Source #

Like queryUnion, but applied on all the elements on the list

 action ProjectsAction = do
     let values :: [(ProjectType, Int)] = [(ProjectTypeOngoing, 3), (ProjectTypeNotStarted, 2)]

         valuePairToCondition :: (ProjectType, Int) -> QueryBuilder "projects"
         valuePairToCondition (projectType, participants) =
             query @Project
                 |> filterWhere (#projectType, projectType)
                 |> filterWhere (#participants, participants)

         theQuery = queryUnionList (map valuePairToCondition values)

     projects <- fetch theQuery
     render IndexView { .. }

queryOr :: forall (model :: Symbol). (QueryBuilder model -> QueryBuilder model) -> (QueryBuilder model -> QueryBuilder model) -> QueryBuilder model -> QueryBuilder model Source #

Adds an a OR b condition

Example: Return all pages owned by the user or public.

query @Page
    |> queryOr
        (filterWhere (#createdBy, currentUserId))
        (filterWhere (#public, True))
    |> fetch
-- SELECT * FROM pages WHERE created_by = '..' OR public = True