Filters implementation

package.json

@@ -29,7 +29,7 @@
     "eslint-plugin-import": "^2.2.0",
     "eslint-plugin-prettier": "^2.6.0",
     "flow-bin": "^0.42.0",
-    "jest": "^20.0.0",
+    "jest": "^23.0.0",
     "jest-fetch-mock": "^1.0.8",
     "prettier": "^1.12.1"
   },

src/Filter.js

@@ -0,0 +1,18 @@
+// @flow
+
+/**
+ * @property {string} variable - The variable of this field
+ */
+export default class Filter {
+  property: string;
+  variable: string;
+
+  /**
+   * @param {string} property
+   * @param {string} variable
+   */
+  constructor(property: string, variable: string) {
+    this.property = property;
+    this.variable = variable;
+  }
+}

src/Resource.js

@@ -1,6 +1,7 @@
 // @flow
 
 import Field from "./Field";
+import Filter from "./Filter";
 import Operation from "./Operation";
 
 type ResourceOptions = {
@@ -9,6 +10,7 @@ type ResourceOptions = {
   deprecated?: boolean,
   readableFields?: Field[],
   writableFields?: Field[],
+  filters?: Filter[],
   operations?: Operation[]
 };
 

src/hydra/addFilters.js

@@ -0,0 +1,38 @@
+import Filter from "../Filter";
+import fetchResource from "./fetchResource";
+
+export default api => {
+  const promises = [];
+
+  for (const resource of api.resources) {
+    let promise = fetchResource(resource.url).then(response => {
+      if (!response.filters) {
+        return [];
+      }
+
+      const resourceFilters = [];
+
+      for (const filter of response.filters) {
+        let property = filter.property;
+
+        if (property === null) {
+          continue;
+        }
+
+        resourceFilters.push(new Filter(property, filter.variable));
+      }
+
+      return resourceFilters;
+    });
+
+    promises.push(promise);
+  }
+
+  return Promise.all(promises).then(values => {
+    api.resources.map((resource, index) => {
+      resource.filters = values[index];
+    });
+
+    return api;
+  });
+};

src/hydra/fetchResource.js

@@ -0,0 +1,13 @@
+import fetchJsonLd from "./fetchJsonLd";
+import get from "lodash.get";
+
+export default async entrypointUrl => {
+  return await fetchJsonLd(entrypointUrl, { itemsPerPage: 0 }).then(
+    d => ({
+      filters: get(d, "body.hydra:search.hydra:mapping")
+    }),
+    () => {
+      throw new Error("Unreachable resource");
+    }
+  );
+};