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44577dab1b
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4006 Co-authored-by: Daniel Chambers <1214352+daniel-chambers@users.noreply.github.com> GitOrigin-RevId: 756ca0ed60865d0eb675562e8959f0d1839f9abe
112 lines
4.0 KiB
Haskell
112 lines
4.0 KiB
Haskell
module Hasura.Backends.DataWrapper.IR.Query
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( Query (..),
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Field (..),
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ColumnContents (..),
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RelationshipContents (..),
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PrimaryKey (..),
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ForeignKey (..),
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)
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where
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--------------------------------------------------------------------------------
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import Autodocodec.Extended (getValue)
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import Data.HashMap.Strict qualified as M
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import Hasura.Backends.DataWrapper.API qualified as API
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import Hasura.Backends.DataWrapper.IR.Column qualified as Column (Name)
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import Hasura.Backends.DataWrapper.IR.Expression (Expression)
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import Hasura.Backends.DataWrapper.IR.OrderBy (OrderBy)
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import Hasura.Backends.DataWrapper.IR.Table qualified as Table (Name)
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import Hasura.Prelude
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import Witch
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--------------------------------------------------------------------------------
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-- | An abstract request to retrieve structured data from some source.
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data Query = Query
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{ -- NOTE: We should clarify what the 'Text' key is supposed to indicate.
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fields :: HashMap Text Field,
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-- | Reference to the table these fields are in.
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from :: Table.Name,
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-- | Optionally limit to N results.
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limit :: Maybe Int,
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-- | Optionally offset from the Nth result.
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offset :: Maybe Int,
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-- | Optionally constrain the results to satisfy some predicate.
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where_ :: Maybe Expression,
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-- | Optionally order the results by the value of one or more fields.
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orderBy :: [OrderBy]
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}
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deriving stock (Data, Eq, Generic, Ord, Show)
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instance From API.Query Query where
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from API.Query {from = from_, ..} =
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Query
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{ fields = fmap Witch.from fields,
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from = Witch.from from_,
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limit = limit,
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offset = offset,
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where_ = fmap Witch.from where_,
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orderBy = fmap Witch.from $ maybe [] toList orderBy
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}
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--------------------------------------------------------------------------------
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-- | The specific fields that are targeted by a 'Query'.
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--
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-- A field conceptually falls under one of the two following categories:
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-- 1. a "column" within the data store that the query is being issued against
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-- 2. a "relationship", which indicates that the field is the result of
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-- another query that must be executed on its own
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data Field
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= Column ColumnContents
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| Relationship RelationshipContents
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deriving stock (Data, Eq, Generic, Ord, Show)
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instance From API.Field Field where
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from (API.ColumnField name) = Column $ ColumnContents $ Witch.from (getValue name)
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from (API.RelationshipField (API.RelField hm qu)) =
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let joinCondition = M.mapKeys Witch.from $ fmap Witch.from hm
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query = Witch.from qu
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in Relationship $ RelationshipContents joinCondition query
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--------------------------------------------------------------------------------
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newtype ColumnContents = ColumnContents
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{ column :: Column.Name
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}
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deriving stock (Data, Eq, Generic, Ord, Show)
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-- | A relationship consists of the following components:
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-- - a sub-query, from the perspective that a relationship field will occur
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-- within a broader 'Query'
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-- - a join condition relating the data returned by the sub-query with that
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-- of the broader 'Query'
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--
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-- cf. https://en.wikipedia.org/wiki/Join_(SQL)
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-- https://www.postgresql.org/docs/13/tutorial-join.html
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-- https://www.postgresql.org/docs/13/queries-table-expressions.html#QUERIES-FROM
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data RelationshipContents = RelationshipContents
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{ joinCondition :: HashMap PrimaryKey ForeignKey,
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query :: Query
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}
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deriving stock (Data, Eq, Generic, Ord, Show)
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--------------------------------------------------------------------------------
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newtype PrimaryKey = PrimaryKey Column.Name
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deriving stock (Data, Generic)
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deriving newtype (Eq, Hashable, Ord, Show)
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instance From API.PrimaryKey PrimaryKey where
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from (API.PrimaryKey key) = PrimaryKey (Witch.from key)
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--------------------------------------------------------------------------------
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newtype ForeignKey = ForeignKey Column.Name
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deriving stock (Data, Generic)
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deriving newtype (Eq, Hashable, Ord, Show)
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instance From API.ForeignKey ForeignKey where
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from (API.ForeignKey key) = ForeignKey (Witch.from key)
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