ValueMapping

Abstract type of field mappings with effects.

Cursor positioned at a GraphQL result leaf

Root Cursor focussed on the top level operation of a query

Construction of mapping-specific cursors is handled by delegation to mkCursorForField which is typically overridden inMapping` subtypes.

Root effects can perform an intial effect prior to computing the resulting Cursor and effective Query.

These effects are used to perform initial effectful setup for a query or to perform the effect associated with a GraphQL mutation. Convenience methods are provided to cover the cases where only one of the query or the cursor are computed.

If only the query is computed the default root cursor for the mapping will be used. If only the cursor is computed the client query (after elaboration) is used unmodified ... in this case results of the performed effect can only be passed to the result construction stage via the environment associated with the returned cursor.

Root streams can perform an intial effect prior to emitting the resulting cursors and effective queries.

Stream effects are used for GraphQL subscriptions. Convenience methods are provided to cover the cases where only one of the query or the cursor are computed

If only the query is computed the default root cursor for the mapping will be used. If only the cursor is computed the client query (after elaboration) is used unmodified ... in this case results of the performed effect can only be passed to the result construction stage via the environment associated with the returned cursor.

Combine and execute multiple queries.

Each query is interpreted in the context of the Cursor it is paired with. The result list is aligned with the argument query list. For each query at most one stage will be run and the corresponding result may contain deferred components.

Errors are aggregated across all the argument queries and are accumulated on the Left of the result.

This method is typically called at the end of a stage to evaluate deferred subqueries in the result of that stage. These will be grouped by and passed jointly to the responsible mapping in the next stage using this method. Maappongs which are able to benefit from combining queries may do so by overriding this method to implement their specific combinging logic.

Yields a Cursor focused on the top level operation type of the query

True if the supplied type is a leaf with respect to the GraphQL schema or mapping, false otherwise.

Yields a Cursor suitable for traversing the query result corresponding to the fieldName child of parent.

This method is typically overridden in and delegated to by Mapping subtypes.

Yields the RootEffect, if any, associated with fieldName.

Yields the RootStream, if any, associated with fieldName.