The Content Management API (CMA) is a restful API for managing content in your Contentful spaces. You can create, update, delete and retrieve content using well-known HTTP verbs.

To make development easier for our users, we publish SDKs for various languages which make the task easier. This article details how to use the .NET SDK to create, update and delete content.

Pre-requisites

This tutorial assumes you understand the basic Contentful data model as described in the developer center and that you have already read and understand the getting started tutorial for the .NET SDK.

Contentful.net is built on .NET Core and targets .NET Standard 2.0. The SDK is cross-platform and runs on Linux, macOS and Windows.

Your first request

To communicate with the CMA we use a similar approach as when we call the CDA, but instead of a ContentfulClient you use a ContentfulManagementClient that requires three parameters.

1. An HttpClient that makes the HTTP requests to the CMA.
2. An access token. The token has to be a valid management token created using OAuth. To learn more about creating a management token please refer to the documentation.
3. A space id. The id is the unique identifier of your space that you can find in the Contentful web app. This will be the default space for all operations in the SDK, but you can also specify a different space for every operation.

var httpClient = new HttpClient();
var client = new ContentfulManagementClient(httpClient, "<content_management_api_key>", "<space_id>")

Once you have an ContentfulManagementClient you can start managing content. For example, to create a brand new space:

var space = await client.CreateSpace("<space_name>", "<default_locale>", "<organization_id>");
Console.WriteLine(space.Name); // => <space_name>

If your user account belongs to a single organization, you can omit the organization_id parameter.

To delete a space, pass a space id to the DeleteSpace method:

var space = await client.DeleteSpace("<space_id>");

To change the name of an existing space, use the UpdateSpaceName method.

var space = await client.UpdateSpaceName("<space_id>", "<new_space_name>", "<space_version>", "<organization_id>");

Unless your account has more than one organization, you can omit the organization id, but the version parameter is always needed.

This is a common pattern to update operations in the Contentful management API. To update an entry, you need to pass the last known version to make sure that you do not overwrite a resource that has since been updated. This is called 'optimistic locking' and prevents unwanted data loss. If the version passed does not match the latest version in Contentful the update will be rejected and a ContentfulException thrown.

To retrieve the version of a resource, inspect the SystemProperties.Version property.

The following is an example of updating a space:

var space = await client.GetSpace("<space_id>")
var version = space.SystemProperties.Version; // Nullable int
await client.UpdateSpaceName("<space_id>", "<new_space_name>", version.Value);

Working with content types

Once you've familiarized yourself with creating and deleting spaces, the next step is to add content types to your space. A content type in Contentful is a blueprint for an entry and contains up to 50 fields that you can define.

First create a new ContentType object, initialize it's system properties, give it an ID, name, and description:

var contentType = new ContentType();
contentType.SystemProperties = new SystemProperties();
contentType.SystemProperties.Id = "<content_type_id>";
contentType.Name = "Product";
contentType.Description = "";

Create a List of field types, and add all the fields for your content model to it. The example below shows you how to recreate the 'Product' content type you find in our examples spaces, further explanation of the fields follows:

contentType.Fields = new List<Field>()
{
    new Field()
    {
        Name = "Product name",
        Id = "productName",
        Type = "Text",
        Required = true,
        Localized = false,
        Disabled = false,
        Omitted = false,
    },
    new Field()
    {
        Name = "Slug",
        Id = "slug",
        Type = "Symbol",
        Required = false,
        Localized = true,
        Disabled = false,
        Omitted = false
    },
    new Field()
    {
        Name = "Description",
        Id = "productDescription",
        Type = "Text",
        Required = false,
        Localized = false,
        Disabled = true,
        Omitted = false
    },
    new Field()
    {
        Name = "Size/Type/Color",
        Id = "sizetypecolor",
        Type = "Symbol",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false
    },
    new Field()
    {
        Name = "Image",
        Id = "image",
        Type = "Asset",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false,
        LinkType = "Asset",
        Validations = new List<IFieldValidator>() {
            new MimeTypeValidator(MimeTypeRestriction.Image, "My custom validation message")
        }
    },
    new Field()
    {
        Name = "Tags",
        Id = "tags",
        Type = "Array",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false,
        Items = new Schema() {
            Type = "Symbol"
        },
    },
    new Field()
    {
        Name = "Categories",
        Id = "categories",
        Type = "Array",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false,
        Items = new Schema() {
          Type = "Link",
          LinkType = "Entry"
        },
    },
    new Field()
    {
        Name = "Price",
        Id = "price",
        Type = "Number",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false
    },
    new Field()
    {
        Name = "Brand",
        Id = "brand",
        Type = "Link",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false,
        LinkType = "Entry"
    },
    new Field()
    {
        Name = "Quantity",
        Id = "quantity",
        Type = "Integer",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false
    },
    new Field()
    {
        Name = "SKU",
        Id = "sku",
        Type = "Symbol",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false
    },
    new Field()
    {
        Name = "Available at",
        Id = "website",
        Type = "Symbol",
        Required = false,
        Localized = false,
        Disabled = false,
        Omitted = false,
        Validations = new List<IFieldValidator>() {
          // REGEX
        }
    },
};

Define which field is the display field, and send the new content type declaration to the client.

contentType.DisplayField = "productName";

await _client.CreateOrUpdateContentType(contentType);

The fields have a lot of properties and can look daunting at first, especially if you add validations, so let's break the components down. Every field can consist of up to 10 properties.

new Field()
{
    Name = "The name of the field", // The human readable name of the field e.g. "Top image" or "Main heading"
    Id = "field1", // The id for the field, must be between 2 and 60 characters long and only include alphanumerical characters, dashes, underscores or periods.
    Type = "Link", // The field type. This determines how the data is stored. E.g. "Date", "Text" or "Integer".
    Required = false, // Whether this field is mandatory for this content type.
    Localized = false, // Whether this field should be localized.
    Disabled = false, // Whether this field is disabled for editing.
    Omitted = false, // Whether this field should be omitted from the API response entirely
    LinkType = "Entry",  // Applicable if Type is "Link", whether this links to an Entry or an Asset
    Items = new Schema() {  // Applicable if the Type is "Array" and specifies allowed item types for the array
        Type = "Link", // The type this array field should contain, e.g. "Symbol" or "Link"
        LinkType = "Entry" // Applicable if the item type is Link, specifies whether the array contains Entry or Asset
    },
    Validations = new List<IFieldValidator>() // See validations section below
}

But at a minimum, you need to specify the name, id, and type.

new Field()
{
    Name = "Product name",
    Id = "productName",
    Type = "Text",
}

Field validations

The most complex part of fields is handling validations. You can use different validators that all implement the IFieldValidator interface. Every validator has a Message property where you can specify a custom message to show if the validation fails.

LinkContentTypeValidator

The LinkContentTypeValidator validates that a given field contains entries of a particular content type. The constructor takes an optional message and any number of string ids or content types to validate against.

new Field()
{
  Name = "Brand",
  Id = "brand",
  Type = "Link",
  Validations = new List<IFieldValidator>() {
      new LinkContentTypeValidator(message: "My custom validation message", "<content_type_id>", "<content_type_id>" ...)
  }
}

InValuesValidator

The InValuesValidator validates that a given field value is within a predefined set of values. The constructor takes an optional message and any number of strings to validate against.

new Field()
{
  Name = "Tags",
  Id = "tags",
  Type = "Text",
  Validations = new List<IFieldValidator>() {
      new InValuesValidator(message: "This is not a valid tag", "<value1>", "<value2>" ...)
  }
}

MimeTypeValidator

The MimeTypeValidator validates that an asset is of a particular mime type group.

new Field()
{
    Name = "Image",
    Id = "image",
    Type = "Text",
    Validations = new List<IFieldValidator>() {
        new MimeTypeValidator(MimeTypeRestriction.Image, "Not a valid image")
    }
}

Available restrictions are:

• MimeTypeRestriction.Attachment
• MimeTypeRestriction.Plaintext
• MimeTypeRestriction.Image
• MimeTypeRestriction.Audio
• MimeTypeRestriction.Video
• MimeTypeRestriction.Richtext
• MimeTypeRestriction.Presentation
• MimeTypeRestriction.Spreadsheet
• MimeTypeRestriction.PdfDocument
• MimeTypeRestriction.Archive
• MimeTypeRestriction.Code
• MimeTypeRestriction.Markup

SizeValidator

The SizeValidator validates that an array field contains a specific number of items.

new Field()
{
    Name = "Tags",
    Id = "tags",
    Type = "Array",
    Validations = new List<IFieldValidator>() {
        new SizeValidator(min: 2, max: 7, message: "Sorry, you must add between 2 and 7 tags.")
    }
}

Both the min and the max value are nullable. You can create size validators that validate that an array contains at least a set number of items, but without an upper bound. Or contains a maximum of a set number of items but may also be empty.

// This SizeValidator allows a maximum of 5 items, but as it has no minimum value it can contain 0 items.
new SizeValidator(min: null, max: 5, message: "Sorry, you may add a maximum of 5 tags.")

// This SizeValidator specifies that the field must contain at least 4 items, but there is no upper bound.
new SizeValidator(min: 4, max: null, message: "Sorry, you must add at least 4 tags.")

RangeValidator

The RangeValidator validates that a field is within a particular numeric range.

new Field()
{
  Name = "Quantity",
  Id = "quantity",
  Type = "Number",
  Validations = new List<IFieldValidator>() {
      new RangeValidator(min: 10, max: 1000, message: "Quantities must be between 10 and 1000.")
  }
}

When used for text fields it validates that the entered value contains at least the minimum number of characters and at most the maximum number of characters. For numeric fields, it validates that the value entered is within the specified range. Both the min and max value are nullable in the same way as for the SizeValidator.

RegexValidator

The RegexValidator validates that a field conforms to a specified regular expression.

new Field()
  {
  Name = "Availabe at",
  Id = "website",
  Type = "Symbol",
  Validations = new List<IFieldValidator>() {
      new RegexValidator(expression: "\\b((?:[a-z][\\w-]+:(?:\\/{1,3}|[a-z0-9%])|www\\d{0,3}[.]|[a-z0-9.\\-]+[.][a-z]{2,4}\\/)(?:[^\\s()<>]+|\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\))+(?:\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\)|[^\\s`!()\\[\\]{};:'\".,<>?«»“”‘’]))", flags: "i", message: "The value isn't a valid web address.")
  }
}

UniqueValidator

The UniqueValidator validates that the field values is unique among all entries.

new Field()
{
  Name = "Name",
  Id = "productName",
  Type = "Text",
  Validations = new List<IFieldValidator>() {
      new UniqueValidator(message: "Sorry, product names must be unique.")
  }
}

Activate a content type

Once you have created a content type you need to activate it before it's usable.

var contentType = await client.ActivateContentType("<content_type_id>", version: 7);

You can deactivate the content type in a similar fashion, but you don't need to specify a version as there is no risk of data loss.

var contentType = await client.DeactivateContentType("<content_type_id>");

Deleting a content type is similar, you must deactivate a content type before deleting it.

var contentType = await client.DeleteContentType("<content_type_id>");

There are three methods available to fetch content types.

var contentTypes = await client.GetContentTypes(); // Gets all content types of the space
var contentType = await client.GetContentType("<content_type_id>"); // Gets a single content type
var activeContentTypes = await client.GetActivatedContentTypes(); // Gets the latest activated version of all content types

Editor interface

An editor interface represents information about how the user interface displays the fields of a content type.

Every content type has its own Editor interface, and you cannot explicitly create it. Instead, you retrieve and update it appropriately.

var editorInterface = await client.GetEditorInterface("<content_type_id>");

Once you have the editor interface, you can update it and change how certain fields are displayed.

var editorInterface = await client.GetEditorInterface("<content_type_id>");

editorInterface.Controls.First(f => f.FieldId == "productName").WidgetId = SystemWidgetIds.SingleLine;

var boolField = editorInterface.Controls.First(f => f.FieldId == "preorder")
boolField.WidgetId = SystemWidgetIds.Boolean;
boolField.Settings = new BooleanEditorInterfaceControlSettings()
{
  HelpText = "Is the product available?",
  TrueLabel = "Yes",
  FalseLabel = "No"
}
await client.UpdateEditorInterface(editorInterface, "<content_type_id>", editorInterface.SystemProperties.Version.Value);

An Editor interface consists of a collection of 'controls'. These are of type EditorInterfaceControl which has three different properties.

var editorInterfaceControl =  new EditorInterfaceControl()
{
  FieldId = "<field_id>",
  WidgetId = "<widget_id>",
  Settings = new EditorInterfaceControlSettings()
}

The FieldId is the id of the field that this EditorInterfaceControl controls the appearance of, and the WidgetId is the widget type you want the control to display as. There's a handy SystemWidgetIds class that contains all built in ids, for a full list refer to the API documentation.

The Settings property contains settings for certain widget types. Normally it's of type EditorInterfaceControlSettings and has only a HelpText property which represents the help text you want to display in relation to your field control. There are three distinct subclasses of EditorInterfaceControlSettings for specific fields.

var boolEditorInterfaceControlSettings = new BooleanEditorInterfaceControlSettings()
{
  HelpText = "Is the product available?",
  TrueLabel = "Yes",
  FalseLabel = "No"
};

var ratingEditorInterfaceControlSettings = new RatingEditorInterfaceControlSettings()
{
  HelpText = "Rate the product",
  NumberOfStars = 7, // The number of stars to display in the rating widget, default is 5
};

var datepickerEditorInterfaceControlSettings = new DatePickerEditorInterfaceControlSettings()
{
  HelpText = "Set the date of release",
  DateFormat = EditorInterfaceDateFormat.time, // The format of the date, can be time, timeZ or dateonly
  ClockFormat = "24" // The format of the clock, can be 12 or 24
}

Working with entries

You fetch entries in a similar way to using the Content Delivery API (CDA), but with three key differences:

• Every entry will always include all configured locales.
• Calls will include unpublished entries.
• The CMA does not cache calls as rigorously as the CDA.

For these reasons, it's better to use the CDA and the ContentfulClient provided by the .NET SDK if you're only fetching content. At times it can be convenient to use the CMA as well.

For example, to get all entries for a space you can pass a QueryBuilder to filter which entries to return.

var entries = await client.GetEntriesCollection<Entry<dynamic>>();

Or to get a single entry.

var entry = await _client.GetEntry("<entry_id>");

To create (or update) an entry use the CreateOrUpdateEntry method. Since you need to provide all the locales the simplest way to model fields is with dictionaries.

var entry = new Entry<dynamic>();
entry.SystemProperties = new SystemProperties();
entry.SystemProperties.Id = "Accessories";

entry.Fields = new
{
    Title = new Dictionary<string, string>()
    {
        { "en-US", "Accessories" },
        { "sv-SE", "Tillbehör"}
    },
    Icon = new Dictionary<string, string>()
    {
        { "en-US", "Icon" }
    },
    Description = new Dictionary<string, int>()
    {
        { "en-US", "Small items to make you life or home complete." },
        { "sv-SE", "Små saker för att göra ditt liv eller hem komplett." }
    }
};

var newEntry = await _client.CreateOrUpdateEntry(entry, contentTypeId: "<category_content_type_id>");

To create reference fields to other entries or assets you need to mimic the JSON structure of the Contentful API where references look like this:

"sys": {
    "type": "Link",
    "linkType": "Asset",
    "id": "<asset_id>"
}

//or

"sys": {
    "type": "Link",
    "linkType": "Entry",
    "id": "<entry_id>"
}

You can model this in your Entry<dynamic> like this:

var entry = new Entry<dynamic>();
entry.SystemProperties = new SystemProperties();
entry.SystemProperties.Id = "Accessories";

entry.Fields = new
{
    SingleAsset = new Dictionary<string, dynamic>()
    {
        { "en-US", new { sys = { type = "Link", linkType = "Asset", id = "<id_of_asset_reference>" } } },
        { "sv-SE", new { sys = { type = "Link", linkType = "Asset", id = "<id_of_asset_reference>" } } }
    },
    MultipleAssets = new Dictionary<string, List<dynamic>>()
    {
        { "en-US", new List<dynamic> { new { sys = { type = "Link", linkType = "Asset", id = "<id_of_asset_reference>" } } } }
    },
    SingleEntry = new Dictionary<string, dynamic>()
    {
        { "en-US", new { sys = { type = "Link", linkType = "Entry", id = "<id_of_entry_reference>" } } },
        { "sv-SE", new { sys = { type = "Link", linkType = "Entry", id = "<id_of_entry_reference>" } } }
    },
    MultipleEntries = new Dictionary<string, List<dynamic>>()
    {
        { "en-US", new List<dynamic> { new { sys = { type = "Link", linkType = "Entry", id = "<id_of_entry_reference>" } } } }
    }
};

var newEntry = await _client.CreateOrUpdateEntry(entry, contentTypeId: "<category_content_type_id>");

There are also strongly typed helper classes available to model a reference.

var entry = new Entry<dynamic>();
entry.SystemProperties = new SystemProperties();
entry.SystemProperties.Id = "Accessories";

entry.Fields = new
{
    SingleAsset = new Dictionary<string, Reference>()
    {
        { "en-US", new Reference (LinkType = SystemLinkTypes.Asset, Id = "<id_of_asset_reference>") },
        { "sv-SE", new Reference (LinkType = SystemLinkTypes.Asset, Id = "<id_of_asset_reference>") }
    },
    MultipleAssets = new Dictionary<string, List<Reference>>()
    {
        { "en-US", new List<Reference> { new Reference (LinkType = SystemLinkTypes.Asset, Id = "<id_of_asset_reference>") } }
    },
    SingleEntry = new Dictionary<string, Reference>()
    {
        { "en-US", new Reference (SystemLinkTypes.Entry, Id = "<id_of_entry_reference>") },
        { "sv-SE", new Reference (SystemLinkTypes.Entry, Id = "<id_of_entry_reference>") }
    },
    MultipleEntries = new Dictionary<string, List<Reference>>()
    {
        { "en-US", new List<Reference> { new Reference (LinkType = SystemLinkTypes.Entry, Id = "<id_of_entry_reference>") } }
    }
};

var newEntry = await _client.CreateOrUpdateEntry(entry, contentTypeId: "<category_content_type_id>");

You do not need to use Entry<dynamic> when creating or updating entries. There are generic methods available that let you use a custom type instead.

var product = new Product();
product.Title = new Dictionary<string, string>() { { "en-US", "Bread" } };

await client.CreateEntry<Product>(product, contentTypeId:"product");

var product = new Product();
product.Title = new Dictionary<string, string>() { { "en-US", "Bread" } };

await client.CreateOrUpdateEntry<Product>(product, id:"abc123", version: 12);

If you wish to update just a specific locale for an entry you can use the UpdateEntryForLocale method. In this case you do not need to wrap your properties in dictionaries.

var product = new Product();
product.Title = "Fidget spinner";

await client.UpdateEntryForLocale<Product>(product, id: "abc123", locale: "en-US");
//locale will default to the default locale of the space, which means you can omit it if you're setting values for the default locale.

You can publish/unpublish, archive/unarchive and delete entries.

For example, to publish the specified version of an entry and make it publicly available through the CDA.

client.PublishEntry("<entry_id>", version);

Or to unpublish a specified version.

client.UnpublishEntry("<entry_id>", version);

To archive an entry. You can only archive an entry if it's not published.

client.ArchiveEntry("<entry_id>", version);

To unarchive an entry.

client.UnarchiveEntry("<entry_id>", version);

To permanently delete an entry.

client.DeleteEntry("<entry_id>", version);

Working with assets

You fetch assets in a similar way to fetching entries. It includes all the locales for an asset, unpublished assets, and calls are not cached to the same level.

The ContentfulManagementClient returns ManagementAssets as opposed to the Assets returned from ContentfulClient. This is because every property is a Dictionary containing the value for each locale.

var assets = await client.GetAssetsCollection();

var publishedAssets = await client.GetPublishedAssetsCollection();

var asset = await client.GetAsset("<asset_id>");
var title = asset.Title["en-US"];
var swedishTitle = asset.Title["sv-SE"];
var englishAssetUrl = asset.Files["en-US"].Url;

To create an asset, initialize a ManagementAsset and pass it to the CreateOrUpdateAsset method.

var managementAsset = new ManagementAsset();

managementAsset.SystemProperties = new SystemProperties();
managementAsset.SystemProperties.Id = "<new_asset_id>";

managementAsset.Title = new Dictionary<string, string> {
    { "en-US", "New asset" },
    { "sv-SE", "Ny tillgång" }
};

managementAsset.Files = new Dictionary<string, File>
{
    { "en-US", new File() {
            ContentType = "image/png",
            FileName = "image.png",
            UploadUrl = "https://example.com/image.png"
        }
    },
    { "sv-SE", new File() {
            ContentType = "image/png",
            FileName = "image.png",
            UploadUrl = "https://example.com/image-SE.png"
        }
    }
};

await client.CreateOrUpdateAsset(managementAsset);

After you have created an asset, you need to process it, which moves it to the Contentful AWS buckets and CDN servers.

await client.ProcessAsset("<new_asset_id>", version, locale);

As with entries, you can publish/unpublish, archive/unarchive and delete assets.

To publish a particular version of the asset and make it publicly available through the CDA.

await client.PublishAsset("<new_asset_id>", version);

To unpublish a specified version.

await client.UnpublishAsset("<new_asset_id>", version);

To archive an entry. You can only archive an asset if it's not published.

await client.ArchiveAsset("<new_asset_id>", version);

To unarchive an asset.

await client.UnarchiveAsset("<new_asset_id>", version);

To permanently delete an asset.

await client.DeleteAsset("<new_asset_id>", version);

Uploading files directly

At times you want to upload a file directly from disk or some other source. You then use the UploadReference property of your ManagementAsset. To create an UploadReference use the UploadFile method.

First upload your binary file.

var binaryFileByteArray = File.ReadAllBytes("c:\example\yourfile.txt");
var uploadReference = await client.UploadFile("<new_asset_id>", version);

This returns an UploadReference that can then be used when creating an asset. You need to remove a few properties from the SystemProperties of the reference. This is because these properties are not allowed when creating assets.

//Set the properties that are not allowed to null to make sure they're not serialized with the request.
uploadReference.SystemProperties.CreatedAt = null;
uploadReference.SystemProperties.CreatedBy = null;
uploadReference.SystemProperties.Space = null;

var managementAsset = new ManagementAsset();

managementAsset.SystemProperties = new SystemProperties();
managementAsset.SystemProperties.Id = "<new_asset_id>";

managementAsset.Title = new Dictionary<string, string> {
    { "en-US", "New asset" }
};

managementAsset.Files = new Dictionary<string, File>
{
    { "en-US", new File() {
            ContentType = "text/plain",
            FileName = "your-file.txt",
            UploadReference = uploadReference;
        }
    }
};

await client.CreateOrUpdateAsset(managementAsset);

The asset then needs to be processed as in the previous example.

This way of creating asssets through an upload is quite arduous. The .NET SDK therefore provides a way to create, upload and process a file in one call by using the UploadFileAndCreateAsset method.

var bytes = File.ReadAllBytes("c:\example\yourfile.txt");

var managementAsset = new ManagementAsset();

managementAsset.SystemProperties = new SystemProperties();
managementAsset.SystemProperties.Id = "<new_asset_id>";

managementAsset.Title = new Dictionary<string, string> {
    { "en-US", "New asset" }
};

managementAsset.Files = new Dictionary<string, File>
{
    { "en-US", new File() {
            ContentType = "text/plain",
            FileName = "your-file.txt"
        }
    }
};

await client.UploadFileAndCreateAsset(managementAsset, bytes);

This will upload the file, create the asset, associate the upload with the asset and finally process the asset. It is then ready to be published.

You can also get and delete a previously uploaded UploadReference.

await client.GetUpload("<upload_reference_id>");

await client.DeleteUpload("<upload_reference_id>");

Working with locales

Locales allow you to define translatable fields for entries and assets. To fetch all configured locales for a space, use the GetLocalesCollection method.

var locales = await client.GetLocalesCollection(); // Fetches all locales for a space.

var locale = await client.GetLocale("<locale_id>"); // Note that this parameter is not the locale code or name, but the actual id.
locale.Code; // => "en-GB"
locale.Name; // => "British English"

To create a locale you need to define some properties.

var newLocale = new Local()
{
    Name = "Swenglish", // The name of the locale
    Code = "en-SV", // The code of the locale, can be an arbitrary string
    FallbackCode = "en-GB", // The code of the locale to fallback to if this locale is missing a translation for a given field
    Optional = true, // Whether this locale allows for empty required fields, this is important to allow a locale to fallback to another locale if missing
    ContentDeliveryApi = true, // Whether this locale should be enabled in the API response for the delivery api
    ContentManagementApi = true // Whether this locale should be visible in the management api
};

await client.CreateLocale(locale);

You can't delete a locale used as a fallback. You first need to delete or update any locale that has the locale you're trying to delete set as a fallback. When you delete a locale you delete all content associated with that locale. It's not possible to reverse this action and all content will be permanently deleted.

await client.DeleteLocale("<locale_id>");