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https://github.com/silverstripe/silverstripe-framework
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78 lines
2.2 KiB
Markdown
78 lines
2.2 KiB
Markdown
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---
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title: Adding arguments
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summary: Add arguments to your fields, queries, and mutations
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---
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# Working with generic types
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[CHILDREN asList]
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[alert]
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You are viewing docs for a pre-release version of silverstripe/graphql (4.x).
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Help us improve it by joining #graphql on the [Community Slack](https://www.silverstripe.org/blog/community-slack-channel/),
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and report any issues at [github.com/silverstripe/silverstripe-graphql](https://github.com/silverstripe/silverstripe-graphql).
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Docs for the current stable version (3.x) can be found
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[here](https://github.com/silverstripe/silverstripe-graphql/tree/3)
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[/alert]
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## Adding arguments
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Fields can have arguments, and queries are just fields, so let's add a simple
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way of influencing our query response:
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**app/_graphql/schema.yml**
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```yaml
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queries:
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'readCountries(limit: Int!)': '[Country]'
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```
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We've provided the required argument `limit` to the query, which will allow us to truncate the results.
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Let's update the resolver accordingly.
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```php
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public static function resolveReadCountries($obj, array $args = [])
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{
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$limit = $args['limit'];
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$results = [];
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$countries = Injector::inst()->get(Locales::class)->getCountries();
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$countries = array_slice($countries, 0, $limit);
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foreach ($countries as $code => $name) {
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$results[] = [
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'code' => $code,
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'name' => $name
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];
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}
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return $results;
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}
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```
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Now let's try our query again. This time, notice that the IDE is telling us we're missing a required argument.
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```graphql
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query {
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readCountries(limit: 5) {
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name
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code
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}
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}
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```
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This works pretty well, but maybe it's a bit over the top to *require* the `limit` argument. We want to optimise
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performance, but we also don't want to burden the developer with tedium like this. Let's give it a default value.
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**app/_graphql/schema.yml**
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```yaml
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queries:
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'readCountries(limit: Int = 20)': '[Country]'
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```
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Rebuild the schema, and notice that the IDE is no longer yelling at you for a `limit` argument.
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Let's take this a step further by turning this in to a proper [paginated result](adding_pagination).
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### Further reading
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[CHILDREN]
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