Key Value array in C# put into parameter

Question

Coming from PHP, I have never written C# before and I have encountered something like this in C#:

public string rule(string playerId, string action, params string[] optionalData){
...
}

and in PHP it is like this

public function rule($playerId, $action, $optionalData=array()){
...
}

In PHP I simply fill out the parameter for the $optionalData like this...

myVar->rule("123", "myAction", array('url'=>'review.com');

However in C# I am not sure how to fill the optionalData (params string[] optionalData) parameter as it is a key value parameter (like in the PHP example). My question is how do I create a key value array like the PHP that I created in my example and put into the parameter?

CoolClass cc = new CoolClass();
cc.rule("123", "myAction", ???);

I was searching google and was looking at dictionary and hashmaps etc but I am guessing it is an overkill or it does not work..

Many thanks!

Dictionaries appear to be the right tool for your job - atleast based on what I see here — jdphenix
– jdphenix, Commented Mar 13, 2014 at 4:55

jdphenix · Accepted Answer · 2014-03-13 05:01:58Z

When you were looking at dictionaries, you were definitely looking at the right facility.

If rule() in C# is in your own code, may I recommend changing the signature to:

public string rule(string playerId, string action, IDictionary<string, string> optionalData = new Dictionary<string, string>()){
...
}

What this allows you to do:

Operate on the values in optionalData the way that other C# programmers will expect.
The = new Dictionary<string, string>() part of the suggested method signature make the parameter truly optional. It will not be necessary when calling the method.
You can use IDictionary<T> methods to work with the data. Some syntax you should be somewhat familiar with (consider accessing by key optionalData["someString"].)

However, if rule() is not in your code, you would leave out the optionalData by simply omitting parameters. Examples of valid calls of the original C# method in your question:

rule("Bob", "load")
rule("Bob", "load", "url", "www.example.com") (In this case, optionalData[0].Equals("url", StringComparisonOptions.Ordinal) and optionalData[1].Equals("www.example.com", StringComparisonOptions.Ordinal) is true.

One thing to consider about the original method - keep in mind that rule("Bob", "load", 'url") is a valid call, and you would need to have a run-time check to make sure you had the right number of parameters. Another plus to using a Dictionary<TKey, TValue>. You may even consider writing an adapter method to the original rule(), if you can't change it.

Sadique · Accepted Answer · 2014-03-13 04:44:15Z

0

You can use a Dictionary:

Dictionary<string,string[]>

or something like:

Dictionary<int, string[]>

I believe dictionary will work in your case.

answered Mar 13, 2014 at 4:44

Sadique

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5 Comments

jonprasetyo Over a year ago

This is what I wrote and I am getting errors 'The best overloaded method match for 'ApplicationName.CoolClass.rule(string, string, params string[])' has some invalid arguments

jonprasetyo Over a year ago

This is my code: Dictionary<string, string[]> test = new Dictionary<string, string[]>();

jonprasetyo Over a year ago

string[] names = new string[] {"review"};

jonprasetyo Over a year ago

test.Add("url",names);

Sadique Over a year ago

The first part in Dictionary string or int in our case is the Key - you should be passing PlayerID where you put Url, and in the array pass "url" in the first index of the string array and names in the rest of the array.

knockshore · Accepted Answer · 2014-03-15 17:01:19Z

You can use Dictionary <key_datatype, value_datatype> .

Example:

Your method definition here :

public string rule(string playerId, string action, Dictionary<string, string> optionalData){
...
}

Method call:

Dictionary<string, string> optionalData = new Dictionary<string, string>();
optionalData.Add("url", "review.com");

cc.rule("123", "myAction", optionalData);

Or

you can use DynamoObject to make it more easier to write:

    dynamic optionalData = new ExpandoObject();

//The token after the dynamoObject period will be the key to the assigned value.
    optionalData.url = "review.com";

    cc.rule("123", "myAction", optionalData);

Your method can get the key-value pairs like this:

public string rule(string playerId, string action, dynamic optionalData)
{
...

            foreach (var pair in (IDictionary<string, object>)optionalData)
            {
                if (group.Key == "url")
                {
                   Console.WriteLine(group.Value);
                }
                else if (group.Key == "post")
                {
                    Console.WriteLine(group.Value);
                }
            }
 }

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