--- title: Writing a Thymeleaf component library - part 3 | daily.dev description: Part 3 of a series on building a Thymeleaf component library adds slot support, enabling arbitrary content injection into components. The implementation... canonical: https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Writing a Thymeleaf component library - part 3 | daily.dev og:description: Part 3 of a series on building a Thymeleaf component library adds slot support, enabling arbitrary content injection into components. The implementation... og:url: https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g og:image: https://api.daily.dev/og/posts/uu3guFC8g.png og:image:alt: Writing a Thymeleaf component library - part 3 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Writing a Thymeleaf component library - part 3 **[Wim Deblauwe](https://daily.dev/sources/wim-deblauwe)** · 10 min read · 2 upvotes · 0 comments ## Summary Part 3 of a series on building a Thymeleaf component library adds slot support, enabling arbitrary content injection into components. The implementation introduces a `SlotContentSplitter` helper class that walks a component element's body once, separating default slot content from named slots. A new `SlotElementProcessor` replaces `` elements in component templates with the corresponding provided or default content. The post demonstrates both default and named slots (e.g., header/footer in a card component), shows how to use slots in a button component with SVG icons, and registers the new processor in `TclDialect`. The author acknowledges Claude AI assisted with the complex splitter logic. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I implement named slots in a custom Thymeleaf dialect so components can accept multiple content areas? Add a SlotContentSplitter that walks a component element's body once, routing events to either a default slot model or named slot models captured between matching tcl:slot open and close tags. Store the resulting default slot and a map of named slots as template variables, then use a SlotElementProcessor that reads the name attribute of each tcl:slot tag and substitutes provided content, falling back to the tag's own default content when nothing was supplied. _daily.dev surfaces practical Thymeleaf component patterns like this for developers extending Spring Boot templating._ ### How can a Thymeleaf component support a default slot content that gets overridden only when the caller provides something? In the SlotElementProcessor, capture the tag's own inner markup as default content, then check whether the caller supplied content for that slot name (or the unnamed default slot) via a context variable; if that provided IModel is non-empty, substitute it in place of the default, otherwise keep the default markup as the fallback. _Developers building reusable Thymeleaf components can track implementation walkthroughs like this on daily.dev._ ## Similar posts on daily.dev - [How to supercharge your design system with slots](https://daily.dev/posts/how-to-supercharge-your-design-system-with-slots-cxt3juufa) · Figma · 29 upvotes · 0 comments - [Taming Thymeleaf 4th edition release](https://daily.dev/posts/taming-thymeleaf-4th-edition-release-b42gjrxmq) · Wim Deblauwe · 1 upvotes · 0 comments - [3 Useful Svelte/Sveltekit Features](https://daily.dev/posts/3-useful-svelte-sveltekit-features-yxpguyydy) · Atomic Spin · 1 upvotes · 0 comments - [Code Master Blog: Glimmer DSL for Web 0.8.3 Preventing Components from Shadowing HTML Elements](https://daily.dev/posts/code-master-blog-glimmer-dsl-for-web-0-8-3-preventing-components-from-shadowing-html-elements-qb3y2o2np) · Ruby Flow · 0 upvotes · 0 comments - [Modern Frontend Complexity: essential or accidental?](https://daily.dev/posts/modern-frontend-complexity-essential-or-accidental--yrurnb4gq) · Lobsters · 2 upvotes · 0 comments --- Tags: [#java](https://daily.dev/tags/java), [#spring-boot](https://daily.dev/tags/spring-boot) [View this post on daily.dev](https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Writing a Thymeleaf component library - part 3","url":"https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g"},"datePublished":"2026-08-10T15:58:25.376Z","dateModified":"2026-09-13T19:18:59.010Z","description":"Part 3 of a series on building a Thymeleaf component library adds slot support, enabling arbitrary content injection into components. The implementation...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3af4dc977a3809672421be54cd3c1a13?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3af4dc977a3809672421be54cd3c1a13?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Wim Deblauwe","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Wim Deblauwe","logo":"https://media.daily.dev/image/upload/s--g1qrglrf--/c_limit,w_256/f_auto,q_auto/v1773648779/logos/wim-deblauwe?_a=BAMAMiiu0","url":"https://daily.dev/sources/wim-deblauwe"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"java,spring-boot","timeRequired":"PT10M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Wim Deblauwe","item":"https://daily.dev/sources/wim-deblauwe"},{"@type":"ListItem","position":3,"name":"Writing a Thymeleaf component library - part 3"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/writing-a-thymeleaf-component-library---part-3-uu3gufc8g#faq","mainEntity":[{"@type":"Question","name":"How do I implement named slots in a custom Thymeleaf dialect so components can accept multiple content areas?","acceptedAnswer":{"@type":"Answer","text":"Add a SlotContentSplitter that walks a component element's body once, routing events to either a default slot model or named slot models captured between matching tcl:slot open and close tags. Store the resulting default slot and a map of named slots as template variables, then use a SlotElementProcessor that reads the name attribute of each tcl:slot tag and substitutes provided content, falling back to the tag's own default content when nothing was supplied. daily.dev surfaces practical Thymeleaf component patterns like this for developers extending Spring Boot templating."}},{"@type":"Question","name":"How can a Thymeleaf component support a default slot content that gets overridden only when the caller provides something?","acceptedAnswer":{"@type":"Answer","text":"In the SlotElementProcessor, capture the tag's own inner markup as default content, then check whether the caller supplied content for that slot name (or the unnamed default slot) via a context variable; if that provided IModel is non-empty, substitute it in place of the default, otherwise keep the default markup as the fallback. Developers building reusable Thymeleaf components can track implementation walkthroughs like this on daily.dev."}}]} ```