Add option for dataLoader to enable batching on additionalResolver level (#8475)

* Add option for dataLoader to enable batching on additionalResolver level

I would propose adding data loader options to enable batching on additionalResolver level (to the subgraphs). This would enable us to distribute large workloads to several load-balanced subgraphs.

* docs: update website

* feat: changeset

* chore: apply suggestions

* chore: review nitpicks

Author: PlayAnyData

.changeset/petite-mammals-visit.md

@@ -0,0 +1,6 @@
+---
+'@graphql-mesh/utils': minor
+---
+
+Added data loader options, allowing to specify batching behaviour in additionalResolvers.
+Description available [here](https://the-guild.dev/graphql/mesh/docs/guides/extending-unified-schema)

packages/legacy/utils/src/in-context-sdk.ts

@@ -1,3 +1,4 @@
+import type DataLoader from 'dataloader';
 import type {
   ArgumentNode,
   DocumentNode,
@@ -115,6 +116,7 @@ export function getInContextSDK(
             argsFromKeys,
             valuesFromResults,
             autoSelectionSetWithDepth,
+            dataLoaderOptions,
           }: {
             root: any;
             args: any;
@@ -125,6 +127,7 @@ export function getInContextSDK(
             argsFromKeys?: (keys: string[]) => any;
             valuesFromResults?: (result: any, keys?: string[]) => any;
             autoSelectionSetWithDepth?: number;
+            dataLoaderOptions?: DataLoader.Options<any, any, any>;
           }) => {
             inContextSdkLogger?.debug(`Called with`, {
               args,
@@ -198,6 +201,7 @@ export function getInContextSDK(
                 key,
                 argsFromKeys,
                 valuesFromResults,
+                dataLoaderOptions,
               } as unknown as BatchDelegateOptions;
               if (selectionSet) {
                 const selectionSetFactory = normalizeSelectionSetParamOrFactory(selectionSet);

website/src/pages/docs/guides/extending-unified-schema.mdx

@@ -158,6 +158,10 @@ Any SDK method take the following arguments:
   `{ id name }`
 - `valuesFromResults`: allows to provide a function to transform the results (if the result is an
   array, the function will be mapped to each element)
+- `dataLoaderOptions`: allows you to define the batching behaviour as defined by
+  [dataloader](https://github.com/graphql/dataloader/tree/main?tab=readme-ov-file#api). This allows
+  e.g. to define that retrievals from the subgraph should be done in batches of n ids, which might
+  help in load balancing resource-intensive queries.
 
 <Callout>
   Note: `valuesFromResults`, compared to `selectionSet` helps to "flatten"/"un-nest" data from