ignoreFields option

Author: plmercereau

README.md

@@ -60,7 +60,7 @@ query {
 }
 ```
 
-### Query with arguments 
+### Query with arguments
 
 ```typescript
 import { jsonToGraphQLQuery } from 'json-to-graphql-query';
@@ -200,7 +200,7 @@ query {
 }
 ```
 
-### Query with Enum Values 
+### Query with Enum Values
 
 ```typescript
 import { jsonToGraphQLQuery, EnumType } from 'json-to-graphql-query';
@@ -231,7 +231,7 @@ query {
 }
 ```
 
-### Query with variables 
+### Query with variables
 
 ```typescript
 import { jsonToGraphQLQuery, VariableType } from 'json-to-graphql-query';
@@ -266,6 +266,41 @@ query ($variable1: String!, $variableWithDefault: String = "default_value") {
 }
 ```
 
+### Ignore fields of the initial object
+We sometimes want to ignore specific fields in the initial object, for instance __typename in Apollo queries.
+While we can put the field value to `false`, we might want to keep its value.
+You can specify those fields not to be put into the final GraphQL query though the `ignoreFields` option:
+
+```typescript
+import { jsonToGraphQLQuery, VariableType } from 'json-to-graphql-query';
+
+const query = {
+    query: {
+        Posts: {
+            __ignore: {
+                variable1: 'a value'
+            },
+            id: true,
+            title: true,
+            post_date: true
+        }
+    }
+};
+const graphql_query = jsonToGraphQLQuery(query, { pretty: true, ignoreFields: ['__ignore'] });
+```
+
+Resulting `graphql_query`
+
+```graphql
+query {
+    Posts {
+        id
+        title
+        post_date
+    }
+}
+```
+
 ## TO-DO List
 
  * Support Named Queries / Mutations

src/__tests__/jsonToGraphQLQuery.tests.ts

@@ -281,4 +281,28 @@ describe('jsonToGraphQL()', () => {
         'query { Posts (a: false) { id } Lorem { id } }'
       );
     });
+
+    it('ignores a field that exists in the initial object', () => {
+        const query = {
+            query: {
+                Posts: {
+                    __ignore: {
+                        test: 'a value'
+                    },
+                    id: true,
+                    title: true,
+                    post_date: true
+                }
+            }
+        };
+        expect(jsonToGraphQLQuery(query, { pretty: true, ignoreFields: ['__ignore'] })).to.equal(
+            `query {
+    Posts {
+        id
+        title
+        post_date
+    }
+}`);
+    });
+
 });

src/jsonToGraphQLQuery.ts

@@ -47,16 +47,18 @@ function getIndent(level: number): string {
     return Array((level * 4) + 1).join(' ');
 }
 
-function filterNonConfigFields(fieldName: string) {
-    return fieldName !== '__args' && fieldName !== '__alias' && fieldName !== '__variables';
+function filterNonConfigFields(fieldName: string, ignoreFields: string[]) {
+    return fieldName !== '__args' && fieldName !== '__alias' && fieldName !== '__variables'
+        && ignoreFields.indexOf(fieldName) == -1;
 }
 
-function convertQuery(node: any, level: number, output: Array<[ string, number ]>) {
+function convertQuery(node: any, level: number, ignoreFields: string[], output: Array<[ string, number ]>) {
     Object.keys(node)
-        .filter(filterNonConfigFields)
+        .filter((key) => filterNonConfigFields(key, ignoreFields))
         .forEach((key) => {
         if (typeof node[key] === 'object') {
-            const fieldCount = Object.keys(node[key]).filter(filterNonConfigFields).length;
+            const fieldCount = Object.keys(node[key])
+                .filter((keyCount) => filterNonConfigFields(keyCount, ignoreFields)).length;
             const subFields = fieldCount > 0;
             let token: string;
 
@@ -75,7 +77,7 @@ function convertQuery(node: any, level: number, output: Array<[ string, number ]
             }
 
             output.push([ token + (fieldCount > 0 ? ' {' : ''), level ]);
-            convertQuery(node[key], level + 1, output);
+            convertQuery(node[key], level + 1, ignoreFields, output);
 
             if (subFields) {
                 output.push([ '}', level ]);
@@ -88,6 +90,7 @@ function convertQuery(node: any, level: number, output: Array<[ string, number ]
 
 export interface IJsonToGraphQLOptions {
     pretty?: boolean;
+    ignoreFields?: string[];
 }
 
 export function jsonToGraphQLQuery(query: any, options: IJsonToGraphQLOptions = {}) {
@@ -99,7 +102,7 @@ export function jsonToGraphQLQuery(query: any, options: IJsonToGraphQLOptions =
     }
 
     const queryLines: Array<[string, number]> = [];
-    convertQuery(query, 0, queryLines);
+    convertQuery(query, 0, options.ignoreFields || [], queryLines);
 
     let output = '';
     queryLines.forEach(([line, level]) => {