Define Param Statement

The define_param statement is used to define a parameter in SurrealDB. Parameters provide a way to store and reuse values within queries. This documentation provides an overview of the syntax and usage of the define_param statement.

Table of Contents

• Syntax
• Examples
  • Define Param Statement

Syntax

The basic syntax of the define_param statement is as follows:

#![allow(unused)]
fn main() {
define_param(param_name: Param) {
    // Parameter definition
}
}

• param_name: The name of the parameter to define.

The define_param statement supports the following features:

• Assigning a value to the parameter.

Examples

Define Param Statement Usage

To define a parameter with a specific value, you can use the following code:

#![allow(unused)]
fn main() {
// Define the parameter
fn endpoint_base() -> Param {
    Param::new("endpoint_base")
}

// Define the param definition itself. This must be run against the database first to use the param.
let statement = define_param(endpoint_base()).value("https://dummyjson.com");
}

In the example above, the define_param statement defines a parameter named "endpoint_base" with a value of "https://dummyjson.com".

Before using the defined parameter, it is important to run the define_param statement to register the parameter with the database. You can do this by calling the run method on the statement object, passing the SurrealDB instance as an argument:

#![allow(unused)]
fn main() {
statement.run(db);
}

Once the define_param statement has been executed, you can use the defined parameter ($endpoint_base) across your codebase in queries and other operations.

You can then reference the parameter name in your queries to utilize the stored value.

#![allow(unused)]
fn main() {
let query = select(All).from(User::table()).where_(endpoint_base().equal_to("https://dummyjson.com"));
}

Now you have learned how to define a parameter using the define_param statement. Parameters provide a way to store and reuse values within queries. Remember to execute the define_param statement to register the parameter with the database before using it in your codebase. Refer to the SurrealDB documentation for more information on parameters and their usage.