silverstripe-framework/docs/en/02_Developer_Guides/19_GraphQL/03_working_with_generic_types/04_adding_arguments.md

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WIP: Add new graphql 4 docs (#9652) * DOCS: Add new graphql 4 docs * Reorganise docs * Docs done * Basic graphql index page * TOC for getting started * show folders on graphql index page * Add middleware note * Docs update * Update docs to reflect flushless schema * Docs updates * Docs for getByLink * Query caching docs * Docs on nested operations * update docs for new graphql dev admin * Docs for configurable operations * Replace readSiteTrees with readPages * Schema defaults docs * Docs for inherited plugins * Docs for customising * * Docs for field whitelisting * Change whitelist word * New docs on modelConfig * Document dev/build extension * Document default/global plugins * Document new input type fields config * Apply suggestions from code review Co-authored-by: Andre Kiste <bergice@users.noreply.github.com> * Note about when procedural schema gets built * Fix link * Apply suggestions from code review Co-authored-by: Andre Kiste <bergice@users.noreply.github.com> * Apply suggestions from code review Co-authored-by: Andre Kiste <bergice@users.noreply.github.com> * DOCS Note about plugins in custom queries * DOCS Note about filter and custom resolvers * DOCS Note about canview paging * DOCS Updated guidance on _extend See https://github.com/silverstripe/silverstripe-graphql/issues/296 * Apply suggestions from code review Co-authored-by: Andre Kiste <bergice@users.noreply.github.com> * DOCS Pre-release warning Co-authored-by: Ingo Schommer <ingo@silverstripe.com> Co-authored-by: Andre Kiste <bergice@users.noreply.github.com> Co-authored-by: Ingo Schommer <me@chillu.com>
2020-10-19 23:56:17 +02:00
---
title: Adding arguments
summary: Add arguments to your fields, queries, and mutations
---
# Working with generic types
[CHILDREN asList]
[alert]
You are viewing docs for a pre-release version of silverstripe/graphql (4.x).
Help us improve it by joining #graphql on the [Community Slack](https://www.silverstripe.org/blog/community-slack-channel/),
and report any issues at [github.com/silverstripe/silverstripe-graphql](https://github.com/silverstripe/silverstripe-graphql).
Docs for the current stable version (3.x) can be found
[here](https://github.com/silverstripe/silverstripe-graphql/tree/3)
[/alert]
## Adding arguments
Fields can have arguments, and queries are just fields, so let's add a simple
way of influencing our query response:
**app/_graphql/schema.yml**
```yaml
queries:
'readCountries(limit: Int!)': '[Country]'
```
We've provided the required argument `limit` to the query, which will allow us to truncate the results.
Let's update the resolver accordingly.
```php
public static function resolveReadCountries($obj, array $args = [])
{
$limit = $args['limit'];
$results = [];
$countries = Injector::inst()->get(Locales::class)->getCountries();
$countries = array_slice($countries, 0, $limit);
foreach ($countries as $code => $name) {
$results[] = [
'code' => $code,
'name' => $name
];
}
return $results;
}
```
Now let's try our query again. This time, notice that the IDE is telling us we're missing a required argument.
```graphql
query {
readCountries(limit: 5) {
name
code
}
}
```
This works pretty well, but maybe it's a bit over the top to *require* the `limit` argument. We want to optimise
performance, but we also don't want to burden the developer with tedium like this. Let's give it a default value.
**app/_graphql/schema.yml**
```yaml
queries:
'readCountries(limit: Int = 20)': '[Country]'
```
Rebuild the schema, and notice that the IDE is no longer yelling at you for a `limit` argument.
Let's take this a step further by turning this in to a proper [paginated result](adding_pagination).
### Further reading
[CHILDREN]