Add Values to a String in C# only if they're not null

Question

I'm trying to create an API call that will pass the parts of an address to an address verification service. The address must be passed as a single query parameter.

Using the following code

string input_address = HttpUtility.UrlEncode( string.Format( "{0} {1} {2} {3}",
            location.Street1, location.Street2, location.City, location.PostalCode ) );

The query succeeds if all parts of the address is present however if multiple parts are missing then + signs accumulate and you end up with a query like. /?api_key=####&query=++ID1+1QD&limit=1 which fails due to the extra '+' signs.

Is it possible to only pass values to a string if they are not null without using a set of if statements?

The full code is below:

string input_key = GetAttributeValue( "APIKey" );
string input_address = HttpUtility.UrlEncode( string.Format( "{0} {1} {2} {3}",
    location.Street1, location.Street2, location.City, location.PostalCode ) );

var client = new RestClient("https://api.ideal-postcodes.co.uk/");
var request = new RestRequest( Method.GET );
request.RequestFormat = DataFormat.Json;
request.Resource = "v1/addresses/";
request.AddParameter("api_key", input_key);
request.AddParameter("query", input_address);
request.AddParameter("limit", "1");
request.AddHeader("Accept", "application/json");
var response = client.Execute( request );

What's wrong with checking if a string is null or empty?

Yuval Itzchakov
– Yuval Itzchakov

2015-02-21 20:09:10 +00:00
Commented Feb 21, 2015 at 20:09 — Yuval Itzchakov
– Yuval Itzchakov, Commented Feb 21, 2015 at 20:09
How does your validation service deal with missing parts?

Henk Holterman
– Henk Holterman

2015-02-21 20:11:29 +00:00
Commented Feb 21, 2015 at 20:11 — Henk Holterman
– Henk Holterman, Commented Feb 21, 2015 at 20:11
String.IsNullOrEmpty?

Gilad
– Gilad

2015-02-21 20:16:22 +00:00
Commented Feb 21, 2015 at 20:16 — Gilad
– Gilad, Commented Feb 21, 2015 at 20:16

Henk Holterman · Accepted Answer · 2015-02-21 20:27:13Z

5

To the core question, Is it possible to only pass values to a string if they are not null without using a set of if statements?

string[] addressParts = 
   { location.Street1, location.Street2, location.City, location.PostalCode};

string inputAddress = string.Join(" ", addressParts.Where(s=> !string.IsNullOrEmpty(s)));
inputAddress = HttpUtility.UrlEncode(inputAddress);

edited Feb 21, 2015 at 20:27

answered Feb 21, 2015 at 20:16

Henk Holterman

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