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63cff8b731
This commit introduces an "experimental" backend adapter to the GraphQL Engine. It defines a high-level interface which will eventually be used as the basis for implementing separate data source query generation & marshaling services that communicate with the GraphQL Engine Server via some protocol. PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2684 Co-authored-by: awjchen <13142944+awjchen@users.noreply.github.com> Co-authored-by: Chris Parks <592078+cdparks@users.noreply.github.com> GitOrigin-RevId: 4463b682142ad6e069e223b88b14db511f634768
76 lines
2.7 KiB
Haskell
76 lines
2.7 KiB
Haskell
module Hasura.Experimental.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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)
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where
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--------------------------------------------------------------------------------
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import Hasura.Experimental.IR.Column qualified as Column (Name)
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import Hasura.Experimental.IR.Expression (Expression)
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import Hasura.Experimental.IR.OrderBy (OrderBy)
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import Hasura.Experimental.IR.Table qualified as Table (Name)
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import Hasura.Prelude
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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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--------------------------------------------------------------------------------
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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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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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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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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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