Keywords

Many record types in Bethesda games carry a list of Keywords, including Armor, Weapon, Npc, Ingestible, MagicEffect, Race, and many more. Mutagen provides convenience methods for checking keyword membership, adding/removing keywords, and more.

HasKeyword

The most common operation is checking whether a record contains a specific keyword. Mutagen provides several overloads:

By EditorIDBy FormLinkBy FormKeyBy Record

INpcGetter npc = ...;
ILinkCache linkCache = ...;

if (npc.HasKeyword("ArmorHeavy", linkCache))
{
    // NPC has the keyword
}

INpcGetter npc = ...;
IFormLinkGetter<IKeywordGetter> armorHeavyKeyword = ...;

if (npc.HasKeyword(armorHeavyKeyword))
{
    // NPC has the keyword
}

INpcGetter npc = ...;
FormKey keywordFormKey = ...;

if (npc.HasKeyword(keywordFormKey))
{
    // NPC has the keyword
}

INpcGetter npc = ...;
IKeywordGetter keyword = ...;

if (npc.HasKeyword(keyword))
{
    // NPC has the keyword
}

HasAnyKeyword

When you need to check against multiple keywords at once:

By EditorIDsBy FormLinksBy FormKeys

IWeaponGetter weapon = ...;
ILinkCache linkCache = ...;

if (weapon.HasAnyKeyword(new[] { "WeapTypeSword", "WeapTypeDagger" }, linkCache))
{
    // Weapon matches at least one of the keywords
}

IWeaponGetter weapon = ...;
IEnumerable<IFormLinkGetter<IKeywordGetter>> swordKeywords = ...;

if (weapon.HasAnyKeyword(swordKeywords))
{
    // Weapon matches at least one of the keywords
}

IWeaponGetter weapon = ...;
IEnumerable<FormKey> keywordFormKeys = ...;

if (weapon.HasAnyKeyword(keywordFormKeys))
{
    // Weapon matches at least one of the keywords
}

TryResolveKeyword

If you need both the check and the resolved Keyword record, use TryResolveKeyword to do both in one call:

By EditorIDBy FormLinkBy FormKey

IArmorGetter armor = ...;
ILinkCache linkCache = ...;

if (armor.TryResolveKeyword("ArmorHeavy", linkCache, out var keyword))
{
    Console.WriteLine($"Found keyword: {keyword.FormKey}");
}

IArmorGetter armor = ...;
IFormLinkGetter<IKeywordGetter> keywordLink = ...;
ILinkCache linkCache = ...;

if (armor.TryResolveKeyword(keywordLink, linkCache, out var keyword))
{
    Console.WriteLine($"Found keyword: {keyword.EditorID}");
}

IArmorGetter armor = ...;
FormKey keywordFormKey = ...;
ILinkCache linkCache = ...;

if (armor.TryResolveKeyword(keywordFormKey, linkCache, out var keyword))
{
    Console.WriteLine($"Found keyword: {keyword.EditorID}");
}

Adding and Removing Keywords

The Keywords property on mutable records is a nullable ExtendedList:

Add a KeywordRemove a Keyword

INpc npc = ...;
IFormLinkGetter<IKeywordGetter> newKeyword = ...;

// Initialize the list if null
npc.Keywords ??= new ExtendedList<IFormLinkGetter<IKeywordGetter>>();
npc.Keywords.Add(newKeyword);

INpc npc = ...;
FormKey keywordToRemove = ...;

npc.Keywords?.RemoveAll(x => x.FormKey == keywordToRemove);

The IKeyworded Interface

Under the hood, all of the above convenience methods are powered by the IKeyworded aspect interface. Any record type that has a Keywords field implements this interface, which means you can write generic code that works across all keyworded record types:

void PrintKeywords(IKeywordedGetter<IKeywordGetter> keyworded)
{
    if (keyworded.Keywords == null) return;

    foreach (var keywordLink in keyworded.Keywords)
    {
        Console.WriteLine($"  Keyword: {keywordLink.FormKey}");
    }
}