Final answer:
To pass dynamic values to a GraphQL query, variables are declared within the query and then provided as a part of a separate variables map when making the request. Variables improve the reusability and security of the queries and are essential for dynamic data handling.
Step-by-step explanation:
Passing dynamic values in a GraphQL query involves the use of variables. This is essential to make the queries reusable and to avoid manual string interpolation, which could make the codebase prone to errors and injections. So, how do you pass a dynamic value to a query in GraphQL?
First, you need to define the variables in your GraphQL query. This is done by declaring the variables as named inputs that are prefixed with a "$" character. For example:
query GetItems($category: String!) {
items(category: $category) {
id
name
}
}
Here, $category is the variable that will hold our dynamic value. Note that you also need to specify the variable's type, which in this case is String!. The exclamation mark signifies that the category variable is non-nullable and must be provided when the query is executed.
Next, you need to pass the actual value for the variable when you make the query call. Typically, this is done via the variables map in your GraphQL request, where the key is the variable name without the dollar sign, and the value is the actual data you want to pass:
{
"category": "books"
}
This JSON structure is sent along with your query to the GraphQL server, often in the body of a POST request.