/
schema.clj
1583 lines (1364 loc) · 67 KB
/
schema.clj
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; Copyright (c) 2017-present Walmart, Inc.
;
; Licensed under the Apache License, Version 2.0 (the "License")
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
; http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
(ns com.walmartlabs.lacinia.schema
"Responsible for constructing and validating the GraphQL schema.
GraphQL schema starts in a format easy to read and maintain as an EDN file.
Compiling the schema performs a number of validations and reorganizations to
make query execution faster and simpler, such as generating a flatter structure for the
schema, and pre-computing many defaults."
(:refer-clojure :exclude [compile])
(:require
[clojure.spec.alpha :as s]
[com.walmartlabs.lacinia.introspection :as introspection]
[com.walmartlabs.lacinia.internal-utils
:refer [map-vals map-kvs filter-vals deep-merge q
is-internal-type-name? sequential-or-set? as-keyword
cond-let ->TaggedValue is-tagged-value? extract-value extract-type-tag
to-message qualified-name]]
[com.walmartlabs.lacinia.resolve :as resolve
:refer [ResolverResult resolve-as combine-results is-resolver-result?]]
[clojure.string :as str]
[clojure.set :refer [difference]]
[clojure.pprint :as pprint]
[com.walmartlabs.lacinia.selector-context :as sc])
(:import
(clojure.lang IObj)
(java.io Writer)))
;; When using Clojure 1.8, the dependency on clojure-future-spec must be included,
;; and this code will trigger
(when (-> *clojure-version* :minor (< 9))
(require '[clojure.future :refer [any? simple-keyword? simple-symbol?]]))
(defrecord CompiledSchema [])
(defn ^:no-doc compiled-schema?
[m]
(instance? CompiledSchema m))
;;-------------------------------------------------------------------------------
;; ## Helpers
(def ^:private graphql-identifier #"(?ix) _* [a-z] [a-z0-9_]*")
(defrecord ^:private CoercionFailure
[message])
(defn coercion-failure
"Returns a special record that indicates a failure coercing a scalar value.
This may be returned from a scalar's :parse or :serialize callback.
This is deprecated in version 0.32.0; just throw an exception instead.
A coercion failure includes a message key, and may also include additional data.
message
: A message string presentable to a user.
data
: An optional map of additional details about the failure."
{:added "0.16.0"
:deprecated "0.32.0"}
([message]
(coercion-failure message nil))
([message data]
(merge (->CoercionFailure message) data)))
(defn is-coercion-failure?
"Is this a coercion error created by [[coercion-failure]]?"
{:added "0.16.0"}
[v]
(instance? CoercionFailure v))
(defn ^:private map-types
"Maps the types of the schema that match the provided category, but leaves
the rest unchanged."
[schema category f]
(reduce-kv (fn [s k v]
(if (-> v :category (= category))
(assoc s k (f v))
s))
schema
schema))
(defn tag-with-type
"Tags a value with a GraphQL type name, a keyword.
The keyword should identify a specific concrete object
(not an interface or union) in the relevent schema.
In most cases, this is accomplished by modifying the value's metadata.
For the more rare case, where a particular type is used rather than a Clojure
map, this function returns a new wrapper instance that combines the value and the type name."
[x type-name]
(cond
;; IObj is the base interface for things that can vary their metadata:
(instance? IObj x)
(vary-meta x assoc ::type-name type-name)
;; From here on is the edge case where a fixed type is used that doesn't
;; support metadata.
;; In some cases, the resolver for a field may tag a value even though it
;; gets re-tagged automatically.
(is-tagged-value? x)
(if (= type-name (extract-type-tag x))
x
(->TaggedValue (extract-value x) type-name))
:else
(->TaggedValue x type-name)))
(defn ^:no-doc type-map
"Reduces a compiled schema to a list of categories and the names of types in that category, useful
for exception reporting."
[schema]
(->> schema
vals
(filter :type-name) ;; ::schema/root has no :type-name
(group-by :category)
(map-vals #(->> (map :type-name %)
(remove is-internal-type-name?)
sort
vec))
;; The above may remove entire categories, drop the keys when
;; all the values have been filtered out.
(filter-vals seq)))
(defn as-conformer
"Creates a clojure.spec/conformer as a wrapper around the supplied function.
The function is only invoked if the value to be conformed is non-nil.
Any exception thrown by the function is silently caught and the returned conformer
will return :clojure.spec/invalid or a [[coercion-failure]].
This function has been deprecated, as Scalar parse and serialize callbacks are now
simple functions, and not conformers."
{:deprecated "0.31.0"}
[f]
(s/conformer
(fn [x]
(try
(when (some? x)
(f x))
(catch Exception e
(if-some [message (.getMessage e)]
(coercion-failure message (ex-data e))
::s/invalid))))))
(defn ^:private parse-int
[v]
;; The serialized is a little more forgiving about converting non-integers to integers.
;; On the parse side, we're a little more picky.
(when (integer? v)
(if (<= Integer/MIN_VALUE v Integer/MAX_VALUE)
(int v)
(coercion-failure "Int value outside of allowed 32 bit integer range." {:value (pr-str v)}))))
(defn ^:private serialize-int
[v]
(cond
(integer? v)
(if (<= Integer/MIN_VALUE v Integer/MAX_VALUE)
(int v)
(coercion-failure "Int value outside of allowed 32 bit integer range." {:value (pr-str v)}))
;; Per spec; floats are allowed only if they are a whole number.
(float? v)
(when (= v (Math/floor (double v)))
(let [long-v (long v)]
(if (<= Integer/MIN_VALUE long-v Integer/MAX_VALUE)
(int long-v)
(coercion-failure "Int value outside of allowed 32 bit integer range." {:value (pr-str v)}))))))
(defn ^:private parse-float
[v]
(cond
(instance? Double v)
v
;; Spec: should coerce non-floating-point raw values as result coercion and for input coercion
(number? v)
(double v)))
(defn ^:private seralize-float
[v]
(cond
(instance? Double v)
v
(number? v)
(double v)
(string? v)
(try
;; Per the spec, if a string can be parsed to a double, that's allowed
(Double/parseDouble v)
(catch Throwable _
nil))))
(defn ^:private parse-boolean
[v]
(when
(instance? Boolean v)
v))
(defn ^:private parse-id
[v]
(cond
(string? v)
v
(integer? v)
(str v)))
(defn ^:private serialize-id
[v]
;; Although the spec discusses serializing the ID type "as appropriate", that would be a case
;; of overriding this default implementation.
(when (string? v)
v))
(defn ^:private parse-string
[v]
(when (string? v)
v))
(def default-scalar-transformers
{:String {:parse parse-string
:serialize str}
:Float {:parse parse-float
:serialize seralize-float}
:Int {:parse parse-int
:serialize serialize-int}
:Boolean {:parse parse-boolean
:serialize parse-boolean}
:ID {:parse parse-id
:serialize serialize-id}})
(defn ^:private error
([message]
(error message nil))
([message data]
(merge {:message message} data)))
;;-------------------------------------------------------------------------------
;; ## Validations
(s/def ::deprecated (s/or :basic true?
:detailed string?))
(s/def ::schema-key (s/and simple-keyword?
::graphql-identifier))
(s/def ::graphql-identifier #(re-matches graphql-identifier (name %)))
;; For style and/or historical reasons, type names can be a keyword or a symbol.
;; The convention is that built-in types use a symbol, and application-defined types
;; use a keyword.
(s/def ::type-name (s/and
(s/nonconforming
(s/or :keyword simple-keyword?
:symbol simple-symbol?))
::graphql-identifier))
(s/def ::type (s/or :base-type ::type-name
:wrapped-type ::wrapped-type))
(s/def ::wrapped-type (s/cat :modifier ::wrapped-type-modifier
:type ::type))
;; Use of a function here, rather than just the set, is due to https://github.com/bhb/expound/issues/101
(s/def ::wrapped-type-modifier #(contains? #{'list 'non-null} %))
(s/def ::arg (s/keys :req-un [::type]
:opt-un [::description
::directives
::default-value]))
(s/def ::default-value any?)
(s/def ::args (s/map-of ::schema-key ::arg))
;; Defining these callbacks in spec has been a challenge. At some point,
;; we can expand this to capture a bit more about what a field resolver
;; is passed and should return.
(s/def ::resolve (s/or :function ::function-or-var
:protocol ::resolver-type))
(s/def ::resolver-type #(satisfies? resolve/FieldResolver %))
(s/def ::field (s/keys :opt-un [::description
::resolve
::args
::directives
::deprecated]
:req-un [::type]))
(s/def ::operation (s/keys :opt-un [::description
::deprecated
::args]
:req-un [::type
::resolve]))
(s/def ::fields (s/map-of ::schema-key ::field))
(s/def ::implements (s/and (s/coll-of ::type-name)
seq))
(s/def ::description string?)
(s/def ::directives (s/coll-of ::directive))
(s/def ::directive (s/keys :req-un [::directive-type]
:opt-un [::directive-args]))
(s/def ::directive-type ::schema-key)
(s/def ::directive-args (s/map-of keyword? any?))
(s/def ::tag (s/or
:symbol symbol?
:class class?))
(s/def ::object (s/keys :req-un [::fields]
:opt-un [::implements
::directives
::description
::tag]))
;; Here we'd prefer a version of ::fields where :resolve was not defined.
(s/def ::interface (s/keys :opt-un [::description
::directives
::fields]))
;; A list of keyword identifying objects that are part of a union.
(s/def ::members (s/and (s/coll-of ::type-name)
seq))
(s/def ::union (s/keys :opt-un [::description
::directives]
:req-un [::members]))
(s/def ::enum-value (s/and (s/nonconforming
(s/or :string string?
:keyword simple-keyword?
:symbol simple-symbol?))
::graphql-identifier))
(s/def ::enum-value-def (s/or :bare-value ::enum-value
:described (s/keys :req-un [::enum-value]
:opt-un [::description
::deprecated
::directives])))
(s/def ::values (s/and (s/coll-of ::enum-value-def) seq))
(s/def ::enum (s/keys :opt-un [::description
::directives]
:req-un [::values]))
;; The type of an input object field is more constrained than an ordinary field, but that is
;; handled with compile-time checks. Input objects should not have a :resolve or :args as well.
;; Defining an input-object in terms of :properties (with a corresponding ::properties and ::property spec)
;; may be more correct, but it's a big change.
(s/def ::input-object (s/keys :opt-un [::description
::directives]
:req-un [::fields]))
;; Prior to 0.31.0, specs were conformers.
;; With the breaking change in 0.31.0, we want to make sure that custom scalars
;; have been updated.
(s/def ::not-a-conformer #(not (s/spec? %)))
(s/def ::parse-or-serialize-fn (s/and ::not-a-conformer
::function-or-var))
(s/def ::function-or-var (s/or :function fn?
:var var?))
(s/def ::parse ::parse-or-serialize-fn)
(s/def ::serialize ::parse-or-serialize-fn)
(s/def ::scalar (s/keys :opt-un [::description
::directives]
:req-un [::parse
::serialize]))
(s/def ::scalars (s/map-of ::schema-key ::scalar))
(s/def ::interfaces (s/map-of ::schema-key ::interface))
(s/def ::objects (s/map-of ::schema-key ::object))
(s/def ::input-objects (s/map-of ::schema-key ::input-object))
(s/def ::enums (s/map-of ::schema-key ::enum))
(s/def ::unions (s/map-of ::schema-key ::union))
(s/def ::context (s/nilable map?))
;; These are the argument values passed to a resolver or streamer;
;; as opposed to ::args which are argument definitions.
(s/def ::arguments (s/nilable (s/map-of ::schema-key any?)))
;; Same issue as with ::resolve.
(s/def ::stream ::function-or-var)
(s/def ::queries (s/map-of ::schema-key ::operation))
(s/def ::mutations (s/map-of ::schema-key ::operation))
(s/def ::subscription (s/keys :opt-un [::description
::resolve
::args]
:req-un [::type
::stream]))
(s/def ::subscriptions (s/map-of ::schema-key ::subscription))
(s/def ::directive-defs (s/map-of ::schema-key ::directive-def))
(s/def ::directive-def (s/keys :opt-un [::description
::args]
:req-un [::locations]))
(s/def ::locations (s/coll-of ::location))
(s/def ::location #{:query :mutation :subscription
:field :fragment-definition :fragment-spread :inline-fragment
:schema :scalar :object
:field-definition :argument-definition :interface
:union :enum :enum-value :input-object :input-field-definition})
(s/def ::roots (s/map-of #{:query :mutation :subscription} ::schema-key))
(s/def ::schema-object
(s/keys :opt-un [::scalars
::interfaces
::objects
::input-objects
::enums
::unions
::roots
::queries
::mutations
::subscriptions
;; Schema-level directives
::directives
::directive-defs]))
;; Again, this can be fleshed out once we have a handle on defining specs for
;; functions:
(s/def ::default-field-resolver ::function-or-var)
(s/def ::promote-nils-to-empty-list? boolean?)
(s/def ::enable-introspection? boolean?)
(s/def ::compile-options (s/keys :opt-un [::default-field-resolver
::promote-nils-to-empty-list?
::enable-introspection?]))
(defmulti ^:private check-compatible
"Given two type definitions, dispatches on a vector of the category of the two types.
'Returns true if the two types are compatible.
The interface defines the constraint type, the field defines the constrained type.
This is only invoked when the constraint type and constrained types are not equal.
The rules for this are in section 3.1.2.3 of the spec."
(fn [constraint-type constrained-type]
(mapv :category [constraint-type constrained-type])))
(defmethod check-compatible :default
[_ _]
;; Remember that for object-vs-object, scalar-vs-scalar, and
;; enum-vs-enum, we don't get this far if the types are the same.
;; For disparate types, generally not compatible (e.g., enum vs. scalar).
false)
(defmethod check-compatible [:union :object]
[i-type f-type]
(contains? (:members i-type) (:type-name f-type)))
(defmethod check-compatible [:interface :object]
[i-type f-type]
(contains? (:implements f-type) (:type-name i-type)))
;; That's as far as the spec goes, but one could imagine additonal rules
;; such as a union-vs-union (the field union must be a subset of the interface union),
;; or interface-union (all members of the union must implement the interface).
(defn ^:private is-compatible-type?
"Compares two field type maps (on from the interface, one from the object) for compatibility."
[schema interface-type object-type]
(let [i-kind (:kind interface-type)
o-kind (:kind object-type)
i-type (:type interface-type)
o-type (:type object-type)]
(cond
;; When the object field is non-null and the interface field allows nulls that's ok,
;; the object can be more specific than the interface.
(and (= o-kind :non-null)
(not= i-kind :non-null))
(recur schema i-kind o-type)
;; Otherwise :list must match :list, and :root must match :root,
;; and :non-null must match :non-null
(not= o-kind i-kind)
false
;; For :list and :non-null, they match, move down a level, towards :root
(#{:list :non-null} o-kind)
(recur schema i-type o-type)
;; Shortcut the compatible type check if the exact same type
(= i-type o-type)
true
:else
(check-compatible (get schema i-type)
(get schema o-type)))))
(defn ^:private is-assignable?
"Returns true if the object field is type compatible with the interface field."
[schema interface-field object-field]
(let [interface-type (:type interface-field)
object-type (:type object-field)]
(or (= interface-type object-type)
(is-compatible-type? schema interface-type object-type))))
;;-------------------------------------------------------------------------------
;; ## Types
(defn ^:private expand-type
"Compiles a type from the input schema to the format used in the
compiled schema."
;; TODO: This nested maps format works, but given the simple modifiers
;; we have, just converting from nested lists to a flattened vector
;; might work just as well. It would also make finding the root type
;; cheap: just use last.
[type]
(cond
(sequential? type)
(let [[modifier next-type & anything-else] type
kind (get {'list :list
'non-null :non-null} modifier)]
(when (or (nil? next-type)
(nil? kind)
(seq anything-else))
(throw (ex-info "Expected (list|non-null <type>)."
{:type type})))
{:kind kind
:type (expand-type next-type)})
;; By convention, symbols are used for pre-defined scalar types, and
;; keywords are used for user-defined types, interfaces, unions, enums, etc.
(or (keyword? type)
(symbol? type))
{:kind :root
:type (as-keyword type)}
:else
(throw (ex-info "Could not process type."
{:type type}))))
(defn ^:no-doc root-type-name
"For a compiled field (or argument) definition, delves down through the :type tag to find
the root type name, a keyword."
[field-def]
;; In some error scenarios, the query references an unknown field and
;; the field-def is nil. Without this check, this loops endlessly.
(when field-def
(loop [type-def (:type field-def)]
(if (-> type-def :kind (= :root))
(:type type-def)
(recur (:type type-def))))))
(defn ^:private rewrite-type
"Rewrites the type tag of a field (or argument) into a nested structure of types.
types are maps with two keys, :kind and :type.
:kind may be :list, :non-null, or :root.
:type is a nested type map, or (for :root kind), the keyword name of a
schema type (a scalar, enum, object, etc.)."
[field]
(try
(update field :type expand-type)
(catch Throwable t
(throw (ex-info "Could not identify type of field."
{:field field}
t)))))
(defn ^:private compile-arg
"It's convinient to treat fields and arguments the same at this level."
[arg-name arg-def]
(-> arg-def
rewrite-type
(assoc :arg-name arg-name)))
(defn ^:private compile-field
"Rewrites the type of the field, and the type of any arguments."
[type-def field-name field-def]
(let [{:keys [type-name]} type-def]
(-> field-def
rewrite-type
(assoc :field-name field-name
:qualified-name (qualified-name type-name field-name))
(update :args #(map-kvs (fn [arg-name arg-def]
[arg-name (assoc (compile-arg arg-name arg-def)
:qualified-name (qualified-name type-name field-name arg-name))])
%)))))
(defn ^:private wrap-resolver-to-ensure-resolver-result
[resolver]
(cond
;; The FieldResolver protocol allows a record (e.g., a component) to act as a field
;; resolver. This is where we turn it into a function. We can't tell whether
;; the method will return a ResolverResult or a bare value, so it will end up on
;; the less efficient path (the :else clause).
;; This also works with reify-ed instances of FieldResolver.
(satisfies? resolve/FieldResolver resolver)
(recur (resolve/as-resolver-fn resolver))
;; If a resolver reports its type as ResolverResult, then we don't
;; need to wrap it. This can really add up for all the default resolvers.
;; It's not so important for general resolvers.
(-> resolver meta :tag (identical? ResolverResult))
resolver
;; This is the "less efficient" path, as the result has to be tested to see
;; it is is a resolver result or not.
:else
(fn [context args value]
(let [raw-value (resolver context args value)
is-result? (is-resolver-result? raw-value)]
(if is-result?
raw-value
(resolve-as raw-value))))))
(defn ^:no-doc floor-selector
[selector-context]
(let [callback (:callback selector-context)]
(callback selector-context)))
(defn ^:private selector-error
[selector-context error]
(let [callback (:callback selector-context)]
(-> selector-context
(assoc
:resolved-value nil
:resolved-type nil)
(update :errors conj error)
callback)))
(defn ^:private create-root-selector
"Creates a selector function for the :root kind, which is the point at which
a type refers to something in the schema.
type - object definition containing the field
field - field definition
field-type-name - from the root :root kind "
[schema field-def field-type-name]
(let [field-type (get schema field-type-name)
_ (when (nil? field-type)
(throw (ex-info (format "Field %s references unknown type %s."
(-> field-def :qualified-name q)
(-> field-def :type q))
{:field field-def
:schema-types (type-map schema)})))
category (:category field-type)
;; Build up layers of checks and other logic and a series of chained selector functions.
;; Normally, don't redefine local symbols, but here it makes it easier to follow and less
;; brittle.
selector floor-selector
selector (if (= :scalar category)
(let [serializer (:serialize field-type)]
(fn select-coerion [selector-context]
(cond-let
:let [{:keys [resolved-value]} selector-context]
(nil? resolved-value)
(selector selector-context)
:let [serialized (try
(serializer resolved-value)
(catch Throwable t
(coercion-failure (to-message t) (ex-data t))))]
(nil? serialized)
(selector-error selector-context
(let [value-str (pr-str resolved-value)]
{:message (format "Unable to serialize %s as type %s."
value-str
(q field-type-name))
:value value-str
:type-name field-type-name}))
(is-coercion-failure? serialized)
(selector-error selector-context
(-> serialized
(update :message
#(str "Coercion error serializing value: " %))
(assoc :type-name field-type-name
:value (pr-str resolved-value))))
:else
(selector (assoc selector-context :resolved-value serialized)))))
selector)
selector (if (= :enum category)
(let [possible-values (-> field-type :values set)]
(fn validate-enum [{:keys [resolved-value]
:as selector-context}]
(cond-let
(nil? resolved-value)
(selector selector-context)
:let [keyword-value (as-keyword resolved-value)]
(not (possible-values keyword-value))
(throw (ex-info "Field resolver returned an undefined enum value."
{:resolved-value resolved-value
:enum-values possible-values}))
:else
(selector (assoc selector-context :resolved-value keyword-value)))))
selector)
union-or-interface? (#{:interface :union} category)
selector (if union-or-interface?
(let [member-types (:members field-type)]
(fn select-allowed-types [{:keys [resolved-type resolved-value]
:as selector-context}]
(cond
(or (nil? resolved-value)
(contains? member-types resolved-type))
(selector selector-context)
(nil? resolved-type)
(selector-error selector-context (error "Field resolver returned an instance not tagged with a schema type."))
:else
(selector-error selector-context (error "Value returned from resolver has incorrect type for field."
{:field-type field-type-name
:actual-type resolved-type
:allowed-types member-types})))))
selector)
type-map (when union-or-interface?
(let [member-types (:members field-type)
member-objects (map schema member-types)
type-map (reduce (fn [m {:keys [tag type-name]}]
(if tag
(assoc m tag type-name)
m))
{}
member-objects)]
(when (seq type-map)
type-map)))
selector (fn select-unwrap-tagged-type [selector-context]
(cond-let
;; Use explicitly tagged value (this usually applies to Java objects
;; that can't provide meta data).
:let [resolved-value (:resolved-value selector-context)]
(is-tagged-value? resolved-value)
(selector (assoc selector-context
:resolved-value (extract-value resolved-value)
:resolved-type (extract-type-tag resolved-value)))
;; Check for explicit meta-data:
:let [type-name (-> resolved-value meta ::type-name)]
(some? type-name)
(selector (assoc selector-context :resolved-type type-name))
;; Use, if available, the mapping from tag to object that might be provided
;; for some objects.
:let [resolved-type (when type-map
(->> resolved-value
class
(get type-map)))]
(some? resolved-type)
(selector (assoc selector-context :resolved-type resolved-type))
;; Let a later stage fail if it is a union or interface and there's no explicit
;; type.
:else
(selector selector-context)))
selector (if (#{:object :input-object} category)
(fn select-apply-static-type [selector-context]
;; TODO: Maybe a check that if the resolved value is tagged, that the tag matches the expected tag?
(selector (assoc selector-context :resolved-type field-type-name)))
selector)]
(fn select-require-single-value [{:keys [resolved-value]
:as selector-context}]
(if (sequential-or-set? resolved-value)
(selector-error selector-context
(error "Field resolver returned a collection of values, expected only a single value."))
(selector selector-context)))))
(defn ^:private assemble-selector
"Assembles a selector function for a field.
A selector function is invoked by the executor; it represents a pipeline of operations
that occur before sub-selections occur on the resolved value.
The selector is passed the resolved value and a callback.
The resolved value is expected to be a seq (or nil) if the field type is list.
The callback is passed the final resolved value.
A second, optional, argument is an error map (or seq of error maps).
The selector pipeline must return the value from the callback.
type is a type map, as via rewrite-type."
[schema object-type field type]
(case (:kind type)
:list
(let [next-selector (assemble-selector schema object-type field (:type type))
allow-nil? (not (get-in schema [::options :promote-nils-to-empty-list?]))]
(fn select-list [{:keys [resolved-value callback]
:as selector-context}]
(cond
(and allow-nil? (nil? resolved-value))
(callback (assoc selector-context
:resolved-value nil
:resolved-type nil))
(and allow-nil? (not (sequential-or-set? resolved-value)))
(selector-error selector-context
(error "Field resolver returned a single value, expected a collection of values."))
(not (seq resolved-value))
(callback (assoc selector-context
:resolved-value []
:resolved-type nil))
:else
;; So we have some privileged knowledge here: the callback returns a ResolverResult containing
;; the value. So we need to combine those together into a new ResolverResult.
(let [unwrapper (fn [{:keys [resolved-value] :as selector-context}]
(if-not (sc/is-wrapped-value? resolved-value)
(next-selector selector-context)
(loop [v resolved-value
sc selector-context]
(let [next-v (:value v)
next-sc (sc/apply-wrapped-value sc v)]
(if (sc/is-wrapped-value? next-v)
(recur next-v next-sc)
(next-selector (assoc next-sc :resolved-value next-v)))))))]
(reduce #(combine-results conj %1 %2)
(resolve-as [])
(map-indexed
(fn [i v]
(unwrapper (-> selector-context
(assoc :resolved-value v)
(update-in [:execution-context :path] conj i))))
resolved-value))))))
:non-null
(let [next-selector (assemble-selector schema object-type field (:type type))]
(when (-> field :default-value some?)
(throw (ex-info (format "Field %s is both non-nullable and has a default value."
(-> field :qualified-name q))
{:field-name (:qualified-name field)
:type (:type field)})))
(fn select-non-null [{:keys [resolved-value]
:as selector-context}]
(cond
(nil? resolved-value)
(selector-error selector-context (error "Non-nullable field was null."))
:else
(next-selector selector-context))))
:root ;;
(create-root-selector schema field (:type type))))
(defn ^:private default-field-description
[schema type-def field-name]
(->> type-def
:implements
(map schema)
(keep #(get-in % [:fields field-name :description]))
first))
(defn ^:private provide-default-arg-descriptions
[field-def schema type-def]
(let [interface-defs (->> type-def :implements (map schema))
{:keys [field-name]} field-def
reducer (fn [m arg-name arg-def]
(assoc m arg-name
(if (:description arg-def)
arg-def
(assoc arg-def :description
(->> interface-defs
(keep #(get-in % [:fields field-name :args arg-name :description]))
first)))))]
(update field-def :args #(reduce-kv reducer {} %))))
(defn ^:private prepare-field
"Prepares a field for execution. Provides a default resolver, and wraps it to
ensure it returns a ResolverResult.
Inherits :documentation from matching inteface field as necessary.
Adds a :selector function."
[schema options type-def field-def]
(let [provided-resolver (:resolve field-def)
{:keys [default-field-resolver]} options
{:keys [field-name description]} field-def
type-name (:type-name type-def)
base-resolver (if provided-resolver
provided-resolver
(default-field-resolver field-name))
selector (assemble-selector schema type-def field-def (:type field-def))
wrapped-resolver (cond-> (wrap-resolver-to-ensure-resolver-result base-resolver)
(nil? provided-resolver) (vary-meta assoc ::default-resolver? true))
direct-fn (-> wrapped-resolver meta ::direct-fn)]
(-> field-def
(assoc :type-name type-name
:description (or description
(default-field-description schema type-def field-name))
:resolve wrapped-resolver
:selector selector
:direct-fn direct-fn)
(provide-default-arg-descriptions schema type-def))))
;;-------------------------------------------------------------------------------
;; ## Compile schema
(defn ^:private xfer-types
"Transfers values from the input map to the compiled schema, with checks for name collisions.
The input map keys are type names, and the values are type definitions (matching the indicated
category)."
[compiled-schema input-map category]
(reduce-kv (fn [s k v]
(when (contains? s k)
(throw (ex-info (format "Name collision compiling schema. %s %s conflicts with existing %s."
category
(q k)
(name (get-in s [k :category])))
{:type-name k
:category category
:type v})))
(assoc s k
(assoc v :category category
:type-name k)))
compiled-schema
input-map))
(defn ^:private types-with-category
"Extracts from a compiled schema all the types with a matching category (:object, :interface, etc.)."
[schema category]
(->> schema
vals
(filter #(= category (:category %)))))
(defn ^:private compile-fields
[type-def]
(update type-def :fields #(map-kvs (fn [field-name field-def]
[field-name (compile-field type-def field-name field-def)])
%)))
(defmulti ^:private compile-type
"Performs general compilation and validation of a type from the compiled schema.
May throw an exception if the type fails validation.
Because compilation of types occurs directly on the values, in an indeterminate order,
some further validation and compilation must be delayed until after all types have been compiled."
(fn [type schema] (:category type)))
(defmethod compile-type :default
[type schema]
type)
(defmethod compile-type :union
[union schema]
(let [members (-> union :members set)]
(doseq [member members]
(when-not (seq members)
(throw (ex-info (format "Union %s does not define any members."
(-> union :type-name q))
{:union union})))
(let [type (get schema member)]
(cond
(nil? type)
(throw (ex-info (format "Union %s references unknown type %s."
(-> union :type-name q)
(q member))
{:union union
:schema-types (type-map schema)}))
(not= :object (:category type))
(throw (ex-info (format "Union %s includes member %s of type %s. Members must only be object types."
(-> union :type-name q)
(q member)
(-> type :category name))
{:union union
:schema-types (type-map schema)})))))
(assoc union :members members)))
(defn ^:private apply-deprecated-directive
"For a field definition or enum value definition, checks for a :deprecated annotation and,