Скачать или смотреть How to Pass a Specific Key from $data into a Nested GraphQL Query?

Discover a simple yet effective way to extract a key from your `$data` in GraphQL queries to handle many-to-many relationships seamlessly.
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How to Pass a Specific Key from $data into a Nested GraphQL Query?

When working with GraphQL, one might encounter complex relationships and data handling challenges, especially when dealing with many-to-many relations like publications and tags. In this post, we will focus on a specific problem - how to pass a specific key from a data variable in a GraphQL query.

The Problem

We have a GraphQL schema that includes two input types: GetPublicationsDto and GetTagsForDto. Both types are structured to handle tags, but during our query, we want to fetch publications associated with a certain tagId and also retrieve the corresponding tag data in a single request.

Here is a snippet of the relevant part of the schema:

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

The Attempted Query

A logical attempt to write the GraphQL query looks like this:

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

However, this code fails to compile, returning an error: Variable "$data" of type "GetPublicationsDto!" used in position expecting type "GetTagsForDto!".

Understanding the Error

The error indicates that the tagsFor query expects data of type GetTagsForDto, but is receiving GetPublicationsDto instead. In essence, the two queries require distinct inputs, and the structure of the provided data does not match the expectations of the second query.

The Solution

To resolve this issue, it's essential to separate the input variables and ensure that each query receives the correct data type. Here’s a straightforward solution:

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

Explanation of the Solution

Define Two Variables: We define two separate variables:

$data1 of type GetPublicationsDto!

$data2 of type GetTagsForDto

Pass the Correct Data:

For the publications query, we pass $data1.

For the tagsFor query, we now need to provide $data2.

To extract the necessary tagId from the original $data:

You should handle the extraction of the tagId at the application level (before making the GraphQL query) and provide it when calling the query, or you can directly define $data2 inline in the query if it's a single value.

Example of Inline Definition

If you want to pass the tagId directly from the data structure:

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

However, keep in mind that inline definitions may vary, and the structure needs to support it. Ensure that your GraphQL client handles the input correctly.

Conclusion

In conclusion, when facing issues with GraphQL queries and nested objects, it's crucial to ensure that each query's data structure matches its input requirements. By defining separate variables for your queries, you can more effectively manage distinct data types and avoid compilation errors.

Remember, clear understanding and structured querying are key when navigating complex data relationships in GraphQL.