hicgql

GraphQL in Clojure data structures, Hiccup style.

1. Installation
2. Examples
   1. Operations
   2. Fields, Fragments, and Selections
      1. Arguments and Values
      2. Directives
   3. Aliases
   4. Inline Fragments
   5. Fragment definitions
   6. Clojure sequences
3. Usage with re-graph
4. References
5. License

---

Installation

hicgql is in Clojars. Just add it.

[io.github.timrichardt/hicgql "0.3.0"]

io.github.timrichardt/hicgql {:mvn/version "0.3.0"}

(:require
 [hicgql.core :refer [graphql]])

Examples

GraphQL documents are described with nested vectors, where the first element of each vector is a keyword describing the type of the document element.

[:<ELEMENT-TYPE> :<PROPS?> :<CHILD? OR CHILDREN?>]

hicgql.core/graphql accepts an arbitrary number of operations and renders them concatenated with a\n inbetween.

Operations

Operations are described with :*/ namespaced keywords, e.g. :*/OperationName. Valid types are :query, :mutation, subscription, and can be set via :*/type. Variables are supplied as :$var "Type" pairs.

(graphql
 [:*/Op {:*/type :query
         :$var   "Type"
         :$var2  ["Type2" "default-value"]} :id])

query Op($var: Type, $var2: Type2 = "default-value") {
  id
}

Fields, Fragments, and Selections

Fields with subfields are prefixed by :+/ namespace. Data fields without subfields do not have a namespace.

[:+/fieldWithSubfields
 :subfield1
 :subfield2
 :.../fragment
 [:+/anotherSubfieldedField
  :andSoOn]]

{
  fieldWithSubfields {
    subfield1
    subfield2
    ...fragment
    anotherSubfieldedField {
      andSoOn
    }
  }
}

Arguments and Values

Arguments to fields can be set with a map which is the second element of the selection vector. Argument names are the keys, the values can be clojure data structures that can be meaningfully translated with js/JSON.stringify or cheshire.core/generate-string.

[:+/_
 [:fieldWithArgs {:stringArg "string"
                  :numberArg 2
                  :objArg    {:size [27.32 "cm"]}}]]

{
  fieldWithArgs(stringArg: "string", numberArg: 2, objArg: {size: [27.32 "cm"]})
}

To define a GraphQL document, that does not start with an operation, there is :+/_: [:+/_ field] → { field }.

Directives

Directives can be set with the :! key in the property map. !:'s value has to be a list of directives. A directive is either a key :directive → @directive, or can be supplied with arguments, like a field.

[:+/_
 [:fieldWithDirs {:! [[:dir2 {:arg1 :$var
                              :arg2 'VAL}]
                      :dir1]}]]

{
  fieldWithDirs @dir2(arg1: $var, arg2: VAL) @dir1
}

Directives are applied from bottom to top.

Aliases

Aliases can be set with the :>/ namespace. The name of the keyword is the name of the aliased field.

[:+/_
 [:>/alias [:someField {:arg "val"}]]]

{
  alias: someField(arg: "val")
}

Inline Fragments

Inline fragments are defined with :?/ prefixed keywords. The name of the keyword has to be the type the fragment is of.

[:+/_
 [:?/TypeA :id]]

{
  ... on TypeA {
    id
  }
}

Fragment definitions

Fragments are defined as operations, but with :§/ namespaced keywords. The fragment type has to be set via the :on property.

[:§/Fragment {:on :Type}
 :field]

fragment Fragment on Type {
  field
}

Clojure sequences

It is possible, to use for example for, to generate a list of fields.

[:+/_
 (for [m ["M" "N"]]
   (for [a ["A" "B" "C"]
         x ["X" "Y" "Z"]]
     (keyword (str a x m))))]

{AXM,AYM,AZM,BXM,BYM,BZM,CXM,CYM,CZM,AXN,AYN,AZN,BXN,
BYN,BZN,CXN,CYN,CZN,AXP,AYP,AZP,BXP,BYP,BZP,CXP,CYP,CZP}

Usage with re-graph

re-graph adds the operation type on it's own, so you must not supply the *:/type keyword to the property map.

(re-graph/query
 :query-id
 (graphql
  [:*/MyQuery {:$var "String"}
   [:+/selection {:arg :$var}
    :subfield]])
 {:var "value"}
 callback)

References

1. GraphQL Spec October 2021, http://spec.graphql.org/October2021/
2. Hiccup by James Reeves, https://github.com/weavejester/hiccup
3. re-graph by Oliver Hine, https://github.com/oliyh/re-graph

License

Eclipse Public License https://www.eclipse.org/legal/epl-v10.html