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Learn how to make the `$searchFilter` argument optional in your GraphQL query using Apollo Client, handling conditions with ease.
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How to Conditionally Include a Filtering Argument in a GraphQL Query

GraphQL is an efficient way to build APIs, but sometimes we run into situations where we need to include or exclude query arguments conditionally. One common scenario is needing a filter argument in a query that may or may not be provided. In this guide, we will cover how to conditionally include a filtering argument in a GraphQL query using Apollo Client JavaScript. Let's dive in!

The Problem

You have a GraphQL query like this:

[[See Video to Reveal this Text or Code Snippet]]

This query works perfectly when you pass the $searchFilter to filter results. However, your challenge is to make this argument optional, where passing in null would mean that no filter should be applied. The API you are using requires that the search field in the filter is non-nullable, meaning you cannot pass filter: { search: null }. Thus, you'd like to achieve something like this:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

To handle this, we will use a predefined filter variable. Here's how to structure the solution effectively:

Step 1: Define a Filter Variable

Instead of using $searchFilter directly in your users query, define a filter variable. This filter variable should be of a defined GraphQL input type, say SomeFilterInputType. This can be set as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Pass Variables Correctly

When calling this query, you need to define your query variables in JavaScript. When you want to include a filter, structure it like this:

[[See Video to Reveal this Text or Code Snippet]]

Important Notes

Understanding SomeFilterInputType: This input type can be found in your API specs and is often available in tools like GraphiQL or similar playgrounds. Being aware of your query's argument types will help you use them correctly.

Testing in GraphiQL: You can test your queries easily using GraphiQL or playground. Ensure your variables match the expected structure.

Variables and JavaScript Objects: The variables passed from JavaScript should be structured as an object, allowing you to create or modify them under various conditions easily.

Step 3: Handling Optional Arguments

By marking the SomeFilterInputType without an exclamation mark (i.e., SomeFilterInputType instead of SomeFilterInputType!), you define it as nullable or optional. Here's what this means for your API interaction:

Optional arguments are usually nullable.

If an argument is required in API specs, it should be treated as required on your client-side as well.

Conclusion

By following the steps outlined above, you can effectively conditionally include a filtering argument in your GraphQL queries. This flexibility allows for better handling of user inputs and improved overall API performance. Always remember to check your API specifications to understand the requirements and capabilities of your queries. Happy coding!