R/R6-6.2-executing-operations.R

In gqlr: 'GraphQL' Server in R

# 6.2 - Executing Operations

# The type system, as described in the “Type System” section of the spec, must provide a query root object type. If mutations are supported, it must also provide a mutation root object type.
#
# If the operation is a query, the result of the operation is the result of executing the query’s top level selection set with the query root object type.


# nolint start
# An initial value may be provided when executing a query.
# ExecuteQuery(query, schema, variableValues, initialValue)
#   1. Let queryType be the root Query type in schema.
#   2. Assert: queryType is an Object type.
#   3. Let selectionSet be the top level Selection Set in query.
#   4. Let data be the result of running ExecuteSelectionSet(selectionSet, queryType, initialValue, variableValues) normally (allowing parallelization).
#   5. Let errors be any field errors produced while executing the selection set.
#   6. Return an unordered map containing data and errors.
# nolint end
get_initial_value <- function(initial_value, root_type_object, ..., oh) {

  resolve_fn <- root_type_object$.resolve
  if (is.function(resolve_fn)) {
    initial_value <- root_type_object$.resolve(initial_value, oh$schema)
  }
  if (is.null(initial_value) || is.logical(initial_value)) {
    initial_value <- list()
  }

  # add some default value so that the functions will execute.  Otherwise they are 'NULL' values
  initial_value[["__schema"]] <- function(z1, z2, schema) {
    schema
  }
  initial_value[["__type"]] <- function(z1, args, schema) {
    type_obj <- as_type(args$name)
    type_obj
  }

  initial_value
}

execute_query <- function(operation_obj, initial_value, ..., oh) {

  root_type_object <- oh$schema$get_query_object()
  root_type <- root_type_object$name

  # get default value and add introspection fields
  initial_value <- get_initial_value(initial_value, root_type_object, oh = oh)

  selection_set <- operation_obj$selectionSet

  # could parallelize here if wanted
  data <- execute_selection_set(selection_set, root_type, initial_value, oh = oh)

  return(data)
}



# nolint start
# If the operation is a mutation, the result of the operation is the result of executing the mutation’s top level selection set on the mutation root object type. This selection set should be executed serially.
#
# It is expected that the top level fields in a mutation operation perform side‐effects on the underlying data system. Serial execution of the provided mutations ensures against race conditions during these side‐effects.
#
# ExecuteMutation(mutation, schema, variableValues, initialValue)
#   1. Let mutationType be the root Mutation type in schema.
#   2. Assert: mutationType is an Object type.
#   3. Let selectionSet be the top level Selection Set in mutation.
#   4. Let data be the result of running ExecuteSelectionSet(selectionSet, mutationType, initialValue, variableValues) serially.
#   5. Let errors be any field errors produced while executing the selection set.
#   6. Return an unordered map containing data and errors.
# nolint end
execute_mutation <- function(operation_obj, initial_value, ..., oh) {

  root_type_object <- oh$schema$get_mutation_object()
  root_type <- root_type_object$name

  # get default value and add introspection fields
  initial_value <- get_initial_value(initial_value, root_type_object, oh = oh)

  selection_set <- operation_obj$selectionSet

  # could parallelize here if wanted
  data <- execute_selection_set(selection_set, root_type, initial_value, oh = oh)

  return(data)
}