how to set optional parameter in .net core 6

Question

how to set optional parameter in .net core 6 get method?

Vishal Joshi · Answer

Hello Mukund Pass optional parameters with route constraints. [HttpGet("GetById/{id:int?}")] public Student GetById(int id = 1) { return Student.FirstOrDefault(s => s.Id == id); } The default value will be assigned to the method parameter through the model-binding process. The default model-binder in Web API will convert the value “1” to the numeric value 1. [HttpGet("GetById/{id:int=1}")] public Student GetById(int id) { return Student.FirstOrDefault(s => s.Id == id); } Thanks

Vishal Yelve · Answer

[HttpGet("GetById/{id?}")] example [HttpGet("GetById/{id:int?}")] public Product GetById(int id = 1) { var products = Get(); return products.Where(p => p.Id == id).FirstOrDefault()!; }

Naimish Makwana · Answer

Hello Mukund, You can make a URI parameter optional by adding a question mark to the route parameter. Example : [HttpGet("GetStudent/{studentId?}")] public IActionResult GetStudent(string studentId) {... You can refer below link: https://stackoverflow.com/a/36669280 Thanks Naimish Makwana

Sachin Singh · Answer

You can make any method with optional parameters by just assigning a default value to that parameter. just keep in mind optional parameter should always come at the last of all parameters. public int method(int x=1) { ///to do } public int method(int x=1, int y) // this is wrong and won't work { ///to do } public int method(int x, int y=1) //this is correct { ///to do } public int method(string Name, int age=18) //this is correct { ///to do } public int method(int age,string Name="sachin") //this is correct { ///to do } for web app and API you can also use route concept as discussed by others.

Tuhin Paul · Answer

Hello Mukund, You can set optional parameters in methods using default parameter values. Check this sample snippet: public void MyMethod(int requiredParam, string optionalParam = "default value") { // method body } In the example above, optionalParam is the optional parameter with a default value of "default value". If the caller doesn't provide a value for optionalParam, the default value will be used. You can also use named arguments to skip optional parameters and provide values for later parameters in the method signature. MyMethod(123); // calls MyMethod with requiredParam = 123, optionalParam = "default value" MyMethod(456, "custom value"); // calls MyMethod with requiredParam = 456, optionalParam = "custom value" MyMethod(requiredParam: 789); // calls MyMethod with requiredParam = 789, optionalParam = "default value" Optional parameters must be the last parameters in the method signature. You can't have a required parameter after an optional parameter.