--- title: "Metadata field writers" manual: "LLM Foundation" version: "main" permalink: "https://docs.typo3.org/permalink/netresearch/nr-llm:metadata-field-writers@main" source: "Administration/MetadataTools.rst" rendered: "2026-11-12T15:41:35+00:00" --- # Metadata field writers {#metadata-field-writers} - **`update_page_metadata`** Sets a fixed set of descriptive fields on one page. Editable: `title`, `subtitle`, `nav_title`, `abstract`, `description`, `keywords` and — when EXT:seo is installed — `seo_title`, `og_title`, `og_description`, `twitter_title`, `twitter_description` and `twitter_card`. The last one is a select: its value must be one of the items the TCA declares, and the refusal names them. Anything else (`slug`, `hidden`, `doktype`, `fe_group`, `perms_*`, `no_index`, the image relations …) is refused. Authorised by the acting user's page-edit right; the DataHandler then enforces `tables_modify` and the field-level grants. The two social images have a writer of their own, `set_page_social_image`. - **`set_page_social_image`** Sets the social preview image of one page — `og_image` (Open Graph) or `twitter_image` — to an **existing** managed file, identified by its `sys_file` uid. Both columns come with EXT:seo; without the extension the call is refused and says so. It creates exactly one `sys_file_reference` and never uploads, moves or renames a file ([ADR-195](https://docs.typo3.org/permalink/netresearch/nr-llm:adr-195@main)). Authorised on both ends: the acting user needs page-edit rights on the page, and the file has to lie in a permitted storage inside that user's own file mounts. Either failure is refused in the same words as a page or file that does not exist. Both columns are exclude fields, so a non-admin editor also needs the field-level grants `pages:og_image` / `pages:twitter_image` — without them the whole call is refused **before** anything is written, because the DataHandler would otherwise create the reference and drop the page's side of it in silence. A column an installation hides from non-admins (`displayCond` of `HIDE_FOR_NON_ADMINS`) is refused for every non-admin the same way, and the refusal names the condition. Three things worth knowing before enabling it: - **The field must accept the file.** Both columns accept the image extensions the installation configures (`common-image-types`); a `.txt` is refused rather than written. - **An image that is already there stops the call.** The refusal names the file referenced now; `replace` is the only way past it and it **deletes** that reference first — recoverably (`deleted = 1`) and in `sys_log` — and the approval card says so on its own line. - **Default-language pages only.** A translated page is refused and the default-language page named; whether a translation follows its parent or carries its own image is a page-properties decision (`allowLanguageSynchronization`) the tool leaves to the editor. And because TYPO3 saves a page's translations along with the page, an editor whose allowed languages leave out a language the page is translated into, or who may not edit one of its translations — a translation carries page permissions of its own — is refused before anything is written; the refusal names the translation. The page's own reference count is re-read afterwards, because EXT:seo reads it before it looks for the file: a reference the page does not count is one nothing renders. When that check fails, the new reference is deleted again and the page is written back to what it held; the tool then reads the page once more and the message says whether it is back as the call found it or what is still there, and names anything TYPO3 reported while putting it back — on a translated page that can be a translation it could not re-synchronise, which the tool reports rather than repairs. - **`set_file_alternative_text`** Started from the Editor Action Center, the run sends a downscaled copy of the image to the model ([Vision editor actions](https://docs.typo3.org/permalink/netresearch/nr-llm:configuration-vision@main)). Sets the alternative text (`sys_file_metadata.alternative`) of one managed file, identified by its `sys_file` uid — the accessibility gap an editor most often leaves behind. It writes that one field and nothing else. Authorised by the same storage allow-list and file mounts as the read-only FAL tools; core's own file-metadata permission check (a **writable** file mount) then applies inside the DataHandler, so a read-only mount is refused there. Two limits worth knowing before enabling it: - It **never creates** a metadata record. A file that carries none is refused, in the same words as a file the user may not reach — so the model cannot tell "not yours" from "not indexed". - It writes the default-language metadata in the run's recorded workspace: live in workspace 0, or the corresponding draft in a draft workspace. It takes no language argument and does not translate metadata. Publishing a draft remains a separate action. See [Tools, languages and workspaces](https://docs.typo3.org/permalink/netresearch/nr-llm:tool-workspaces@main). An empty string is accepted and is the correct value for a decorative image. - **`update_fal_asset_meta`** Sets the **title** and the **description** (`sys_file_metadata.title`, `sys_file_metadata.description`) of one managed file, identified by its `sys_file` uid, and the **copyright** notice where EXT:filemetadata provides the column. Any of the fields may be given; at least one is required. It is a second tool rather than a wider `set_file_alternative_text` because the two are deliberately **field-disjoint**: this one does not write the alternative text and that one writes nothing else, so no file field has two writers and an approver never has to work out which of two cards won. It shares the alternative-text tool's whole permission surface — the same storage allow-list and file mounts, core's writable-mount check inside the DataHandler, the same neutral refusal, no metadata record ever created, and default-language metadata in the run's recorded workspace. A draft stays a draft until it is published; see [Tools, languages and workspaces](https://docs.typo3.org/permalink/netresearch/nr-llm:tool-workspaces@main). Two behaviours worth knowing before enabling it: - A field the call **leaves out keeps its stored value**; an **empty string** clears the field it names. The two are not the same, and a call that sets the title never touches a description somebody wrote by hand. - Core marks `title` as an **exclude field** and `description` not, so a non-admin editor needs the field-level grant `sys_file_metadata:title` for the title. Without it the whole call is refused **before** anything is written, rather than the DataHandler dropping the title in silence and applying the description — which would leave the asset described by half of an approved call. The title is bounded in **bytes**, not characters: the column is `tinytext` and holds 255 bytes, so accented and non-Latin characters count for more than one. - **`set_file_categories`** Sets the categories (`sys_file_metadata.categories`) of one managed file, identified by its `sys_file` uid, choosing only from existing categories ([ADR-268](https://docs.typo3.org/permalink/netresearch/nr-llm:adr-268@main)). Started from the Editor Action Center, the run sends a downscaled copy of the image and the list of categories the model may choose from ([Vision editor actions](https://docs.typo3.org/permalink/netresearch/nr-llm:configuration-vision@main)). The list is the categories below the root an administrator names in `vision.categories.rootUid`: live, not hidden, in the default language, and inside the editor's category mounts where the editor has any. At most ten levels below the root and 200 categories are read; a category beyond either limit cannot be chosen, and a file that carries one keeps it. Without a root the tool refuses every call and the editor action is not offered. A uid outside the list refuses the whole call before any approval, and the refusal names the list. No category is ever created. The call names the complete set the file should carry from the list. Categories the file carries from outside the list stay, so an editor's own tagging in another tree is never removed; an empty set removes the file's categories from the list only. The approval card shows the titles before and after, and the uids in its technical details. It shares the alternative-text tool's permission surface — storage allow-list, file mounts, core's writable-mount check, the neutral refusal, no metadata record created, the default-language record only — and works in a draft workspace like it.