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intermediate

The .NET API wrapper is useful for .NET developers who wish to seamlessly integrate the what3words API into their applications, without the hassle of having to manage the low level API calls themselves.

A full example of how to integrate the what3words .NET wrapper is available in our
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1Get API key
2Installation

The artifact is available through NuGet Package what3words.dotnet.wrapper.

dotnet add package what3words.dotnet.wrapper
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3Setup

Use the What3WordsV3

using What3WordsV3;
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4Initialise

Instantiate an instance of What3WordsV3, from which all API requests can be made

var wrapper = new What3WordsV3("YOUR_API_KEY_HERE");
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If you run our Enterprise Suite API Server yourself, you may specify the URL to your own server like so:

var wrapper = new What3Words("YOUR_API_KEY_HERE", "https://api.yourserver.com")
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5Usage

Convert to what3words address

This function converts coordinates (expressed as latitude and longitude) to a what3words address.

More information about ConvertTo3wa, including returned results is available in the what3words REST API documentation.

Find the words for (51.222011, 0.152311):

var result = await wrapper.ConvertTo3WA(new Coordinates(51.222011, 0.152311)).RequestAsync();
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Convert to coordinates

This function converts a what3words address to a position, expressed as coordinates of latitude and longitude.

It takes the words parameter as a string of a what3words 'table.book.chair'

More information about ConvertToCoordinates, including returned results is available in the what3words REST API documentation.

Find the words for ///filled.count.soap:

var result = await wrapper.ConvertToCoordinates("filled.count.soap").RequestAsync();
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AutoSuggest

When presented with a what3words address which may be incorrectly entered, AutoSuggest returns a list of potential correct 3 word addresses. It needs the first two words plus at least the first character of the third word to produce suggestions.

This method provides corrections for mis-typed words (including plural VS singular), and words being in the wrong order.

Optionally, clipping can narrow down the possibilities, and limit results to:

  • One or more countries
  • A geographic area (a circle, box or polygon)

This dramatically improves results, so we recommend that you use clipping if possible.

To improve results even further, set the focus to user’s current location. This will make AutoSuggest return results which are closer to the user.

More information about AutoSuggest, including returned results is available in the what3words REST API documentation.

Code example Simple basic call:

var result = await wrapper.Autosuggest("index.home.r").RequestAsync();
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Code example AutoSuggest, clipping the results returned to the United Kingdom and Belgium:

var result = await wrapper.Autosuggest("index.home.r", new AutosuggestOptions().ClipToCircle('GB,BE')).RequestAsync();
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Code example AutoSuggest, Focus on (51.4243877,-0.34745).

var result = await wrapper.Autosuggest("index.home.r", new AutosuggestOptions().SetFocus(51.4243877,-0.34745)).RequestAsync();
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Code example AutoSuggest, with Generic Voice input type.

var result = await wrapper.Autosuggest("fun with code", new AutosuggestOptions().InputType('generic-voice').RequestAsync();
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Grid section

Grid section returns a section of the what3words 3m x 3m grid as a set of horizontal and vertical lines covering the requested area, which can then be drawn onto a map.

The requested box must not exceed 4km from corner to corner, or a BadBoundingBoxTooBig error will be returned.

More information about GridSection, including returned results is available in the what3words REST API documentation.

Get a grid for (51.222609, 0.152898) in the south-west, and (51.222011, 0.152311 in the north-east:

var result = await wrapper.GridSection(new Coordinates(51.222011, 0.152311), new Coordinates(51.222609, 0.152898)).RequestAsync();
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Available languages

This function returns the currently supported languages. It will return the two letter code, and the name of the language both in that language and in English.

More information about AvailableLanguages, including returned results is available in the what3words REST API documentation.

var result = await wrapper.AvailableLanguages().RequestAsync();
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Handling errors

Success or failure of an API call can be determined through the use of the IsSuccessful propriety.

If it’s been determined that an API call was not successful, Error type and Message values which represent the error, are accessible from through the Error propriety.

var autosuggestResult = await api.Autosuggest(
  "freshen.overlook.clo",
  new AutosuggestOptions().SetClipToCountry(new List<string> { "fr", "de" })
).RequestAsync();

if (autosuggestResult.IsSuccessful) {
  ...
} else {
  if (autosuggestResult.Error.Error == What3WordsError.BadClipToCountry) {
    // Invalid country clip is provided
    Console.WriteLine($"BadClipToCountry: {autosuggestResult.Error.Message}");
  }
}
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6RegEx Functions

This section introduces RegEx functions that can assist with checking and finding possible what3words addresses in strings. The three main functions covered are:

  • isPossible3wa – Match what3words address format;
  • isValid3wa – Verify a what3words address with the API;

isPossible3wa

Our API wrapper RegEx function “isPossible3wa” can be used to detect if a text string (like “filled.count.soap“) in the format of a what3words address without having to ask the API. This functionality checks if a given string could be a what3words address. It returns true if it could be, otherwise false.

Note: This function checks the text format but not the validity of a what3words address. Use isValid3wa to verify validity.

using System;
using what3words.dotnet.wrapper;

namespace What3WordsExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initialize the What3Words API with your API key
            var api = new What3WordsV3("YOUR_API_KEY");

            // Example what3words addresses
            string[] addresses = { "filled.count.soap", "not a 3wa", "not.3wa address" };

            // Check if the addresses are possible what3words addresses
            foreach (var address in addresses)
            {
                bool isPossible = api.IsPossible3wa(address);
                Console.WriteLine($"Is '{address}' a possible what3words address? {isPossible}");
            }
        }
    }
}
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Expected Output

  • isPossible3wa(“filled.count.soap”) returns true
  • isPossible3wa(“not a 3wa”) returns false
  • isPossible3wa(“not.3wa address”)returns false

isValid3wa

Our API wrapper RegEx function “isValid3wa” can be used to determine if a string is a valid what3words address by checking it against the what3words RegEx filter and verifying it with the what3words API.

using System;
using what3words.dotnet.wrapper;

namespace What3WordsExample

class Program
{
    static void Main(string[] args)
    {
        // Initialize the what3words API with your API key
        var api = new What3WordsV3("YOUR_API_KEY");

        // Example addresses
        string[] addresses = {
            "filled.count.soap",
            "filled.count.",
            "coding.is.cool"
        };

        // Check if the addresses are valid what3words addresses
        foreach (var address in addresses)
        {
            bool isValid = api.IsValid3wa(address);
            Console.WriteLine($"Is '{address}' a valid what3words address? {isValid}");
        }
    }
}
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Expected Outputs

  • isValid3wa(“filled.count.soap”) returns True
  • isValid3wa(“filled.count.”) returns False
  • isValid3wa(“coding.is.cool”) returns False

Also make sure to replace <YOUR_API_KEY> with your actual API key. These functionalities provide different levels of validation for what3words addresses, from simply identifying potential addresses to verifying their existence on Earth.

7Troubleshooting

If you encounter errors or issues related to convert-to-coordinate, convert-to-3wa and grid-section requests while using the Free plan, please check the network panel for the following error message Error 402 payment required and its response, indicating the need to upgrade to a higher plan:

{
    "error": {
        "code": "QuotaExceeded",
        "message": "Quota exceeded or API plan does not have access to this feature. Please change your plan at https://accounts.what3words.com/select-plan, or contact support@what3words.com"
    }
}
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For more information, visit our API plans page. If you need further assistance, contact support@what3words.com.

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