feat(gql): a way to get a block and a shape for gql

docs/articles/guide/graphql/quick.md

@@ -190,3 +190,37 @@ It will generate:
   }
 }
 ```
+
+It is also possible to generate a block with fields if to pass an empty string as the query parameter.
+
+```ts
+const shape = toGraphQL('', selectUser);
+```
+
+It will generate:
+
+```graphql
+{
+  id
+  someRel {
+    id
+  }
+  # ...
+}
+```
+
+Or to get a shape if to pass a selector only. 
+
+```ts
+const shape = toGraphQL(selectUser);
+```
+
+It will generate:
+
+```graphql
+id
+someRel {
+  id
+}
+# ...
+```

libs/ngrx-entity-relationship/graphql/src/lib/toGraphQL.ts

@@ -126,10 +126,11 @@ function encodeValue(data: any): string | undefined {
 export function toGraphQL(...queries: Array<string>): string;
 export function toGraphQL(query: string, params: object, selector: ENTITY_SELECTOR): string;
 export function toGraphQL(query: string, selector: ENTITY_SELECTOR): string;
+export function toGraphQL(selector: ENTITY_SELECTOR): string;
 
 export function toGraphQL(...queries: Array<any>): string {
     const prefix = (window as any).ngrxGraphqlPrefix || '';
-    let query = '';
+    let query: string | undefined = '';
     let selector: ENTITY_SELECTOR | undefined;
     let params: Record<string, any> | null | string | undefined;
     if (queries.length >= 2 && typeof queries[1] !== 'string') {
@@ -138,6 +139,9 @@ export function toGraphQL(...queries: Array<any>): string {
         } else {
             [query, selector] = queries;
         }
+    } else if (queries.length === 1 && typeof queries[0] !== 'string') {
+        [selector] = queries;
+        query = undefined;
     }
 
     const stringParams: Array<string> = [];
@@ -165,11 +169,19 @@ export function toGraphQL(...queries: Array<any>): string {
     params = stringParams.length ? `(${stringParams.join(`,${prefix ? ' ' : ''}`)})` : '';
 
     if (selector) {
-        return `{\n${prefix}${query}${params}${prefix ? ' ' : ''}{\n${resolveGraphQL(selector, {
+        let gql = resolveGraphQL(selector, {
             include: [],
             prefix: `${prefix}`,
             level: 2,
-        })}${prefix}}\n}`;
+        });
+
+        if (query === undefined) {
+            return gql;
+        }
+
+        gql = `{\n${gql}${prefix}}`;
+
+        return query ? `{\n${prefix}${query}${params}${prefix ? ' ' : ''}${gql}\n}` : gql;
     }
     const parts: Array<string> = [];
     for (let part of queries) {

libs/ngrx-entity-relationship/test/graphql/src/lib/toGraphQL.spec.ts

@@ -0,0 +1,65 @@
+import {childEntitySelector, rootEntitySelector} from 'ngrx-entity-relationship';
+import {toGraphQL} from 'ngrx-entity-relationship/graphql';
+
+describe('toGraphQL', () => {
+    const root = rootEntitySelector(jasmine.createSpy(), {
+        gqlFields: ['id', 'name'],
+    });
+    const rootChild = childEntitySelector<any, any, any>(jasmine.createSpy(), 'childId', 'child', {
+        gqlFields: ['subId', 'subName'],
+    });
+    const selector = root(rootChild());
+
+    const normalize = (query: string) =>
+        query
+            .replace(/\s+/gm, ' ')
+            .replace(/\s*([{}])\s*/gm, '$1')
+            .trim();
+
+    it('generates a wrapped block with a query', () => {
+        expect(normalize(toGraphQL('data', selector))).toEqual(
+            normalize(`
+            {
+                data {
+                    child {
+                        childId
+                        subId
+                        subName
+                    }
+                    id
+                    name
+                }
+            }`),
+        );
+    });
+
+    it('generates a block with an empty query', () => {
+        expect(normalize(toGraphQL('', selector))).toEqual(
+            normalize(`
+            {
+                child {
+                    childId
+                    subId
+                    subName
+                }
+                id
+                name
+            }
+        `),
+        );
+    });
+
+    it('generates fields without a query', () => {
+        expect(normalize(toGraphQL(selector))).toEqual(
+            normalize(`
+            child {
+                childId
+                subId
+                subName
+            }
+            id
+            name
+        `),
+        );
+    });
+});