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Declarative Programming in CAP: Less Code, More Value
An argument for annotations over handlers, made from the case where it is most obvious: repetitive validation logic that could be declared instead of written. Describes what you want rather than how to get it, and lets the runtime decide the how.
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@sap/cdsCAP@sap/cdsThe CAP Node.js runtime, which compiles the CDS model, serves the services declared in it, answers generic requests before any handler runs, and loads every cds-plugin.Input validationCAPInput validationRejecting bad input before it reaches the database. While this can be done manually inside a handler, there are solutions in place to derive type, range, enum and mandatory checks from the model definitions.
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In the atlas: wrote 8author
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CAP: The Road Ahead - Simplicity in an AI EraCAP: The Road Ahead - Simplicity in an AI EraDevtoberfest 2026 session CAP10, from the head of SAP's Cloud Application Programming Model: forty minutes of live building rather than slides, on the argument that the cheapest code in an AI project is code nobody has to generate. Claude Code builds an invoice-matching workspace from cds init onwards, and each step is one the framework answers rather than the agent: a 42-line domain model that @sap/cds serves as OData and Fiori elements with a status flow, data privacy and change-tracking annotations that produce audit log entries in the console and would reach the SAP Audit Log service once deployed, an imported S/4HANA supplier data product, and semantic matching from a local embedding model after @cap-js/ai is added. The last three steps are annotations: @mcp beside @odata turns the service into an MCP server that a second Claude session queries through @cap-js/mcp, an agent annotation adds the A2A protocol with an agent card and an audit log entry for the agent task, and a skill file gives the agent the matching policy.SAP Developers, published 2026-09-25
Hello React & Vue : SAP CAP’s New UI Layer is Here!Hello React & Vue : SAP CAP’s New UI Layer is Here!CAP gaining a UI layer for React and Vue, which changes the default assumption that the front end is UI5. Short, and the significance is larger than the length.Yogananda, published 2026-06-25
CAP Developers - Call to Action to mitigate and Apply Solution provided in SAP Note 3747787CAP Developers - Call to Action to mitigate and Apply Solution provided in SAP Note 3747787Four malicious npm package versions published on 29 April 2026 that exfiltrate credentials and propagate into adjacent repositories, and what a CAP developer should check. A security advisory rather than a technique, and dated precisely for that reason.Yogananda, published 2026-05-01
CAP, RAP, or Both: Stop Hiding Behind 'It Depends'CAP, RAP, or Both: Stop Hiding Behind 'It Depends'Opens by refusing the answer every other post on this gives — "both are complementary, choose based on context" — and then commits to a framework, including the parts usually left out: the staffing bias behind the decision, and what to do about a landscape with thousands of Z-objects. Argument, not tutorial.published 2026-04-09
What's new in SAP Cloud Application Programming Model – January 2026What's new in SAP Cloud Application Programming Model – January 2026December and January together: the new @assert feature, revised documentation, CDS editor work, and Kyma deployment additions.published 2026-02-09
CAP Heaven? Not Yet — But You Can See It from HereCAP Heaven? Not Yet — But You Can See It from HereAn assessment from someone with Java, Azure and AWS behind them as well as ABAP and Fiori, which is a rarer vantage point than it sounds. The title is the verdict.published 2026-02-07
What's new in SAP Cloud Application Programming Model – November 2025What's new in SAP Cloud Application Programming Model – November 2025The November edition, led by the Status Transition Flows feature presented at reCAP 2025.published 2025-12-08
What's new in SAP Cloud Application Programming Model – September 2025What's new in SAP Cloud Application Programming Model – September 2025The monthly release communication for CAP itself, and this edition carries the MCP servers and the Application Frontend Service integration. Kept because a dated list of what shipped when is the only record of that; three editions are indexed here rather than the whole run.published 2025-10-14
Don't "let it crash", is this the new CAP guideline?Don't "let it crash", is this the new CAP guideline?Dinu traces a change in error handling in CAP's Node.js runtime: @sap/cds@8.2.0 adds a cds.server.shutdown_on_uncaught_errors config flag, defaulting to true, but invoking an operation with an undefined variable no longer takes the server down, with or without the flag, where the same code crashed it on cds@6 and cds@7, and the author notes the old behaviour was already missing in cds@8.1. It still crashes with features.odata_new_adapter turned off to use the old OData parser, so it is the new OData adapter, like the REST adapter before it, that answers an uncaught error with a 500 instead of taking the process down.Dinu, published 2024-09-06
CAPVAL: A project is bornCAPVAL: A project is bornThis second CAPVAL post announces CAPVAL version 2.0, made compatible with CAP v8 after breaking changes there, with the fix shown as a custom cds.middlewares.after error handler. It restates the plugin's @validation.message annotation alongside standard annotations such as @mandatory as the input validation mechanic the project builds on, and the release otherwise adds automated tests and release-automation GitHub Actions rather than new annotations.published 2024-08-26
Extend SAP Cloud Application Programming Model(CAP) Validations with the CAPVAL PluginExtend SAP Cloud Application Programming Model(CAP) Validations with the CAPVAL PluginThe complaint first: the built-in annotations are good for data integrity and poor at telling the user what went wrong, and there is no way to reuse a rule. capval, the plugin the post announces, adds @validation.message alongside the standard annotations rather than replacing them, and @validation.handler for a check written as a class. Published in January 2024, before the 1.2.0 line the README now pairs with @sap/cds 8.0.0 and above; the two annotations it shows are the two the README still documents.published 2024-01-09
SAP CAPv7 - Node.js Highlights and ExperiencesSAP CAPv7 - Node.js Highlights and ExperiencesAn account of upgrading a 100+ table CAP Node.js project from v6 to v7, working through breaking changes in @sap/cds 7: event handlers now always receive an array, service paths move under /odata/v4/... unless serve_on_root is set, and cds-serve replaces cds run. It goes deepest on the GraphQL plugin, @cap-js/graphql: the /graphql endpoint it serves, Composition results wrapped in a nodes connection, and offset-based pagination reached through OData's top and skip rather than GraphQL's own limit and offset.published 2023-08-03
#CAP-TechBytes Input Validation#CAP-TechBytes Input ValidationThe annotations one at a time — @mandatory, @assert.unique, @assert.range including the enum form, @assert.format — each with what it produces. Ends on error handling, which is the part that decides whether any of it is usable from a UI.Thajunniza, published 2023-07-07
[Part - 1] Enrich CAP based Services with Behaviors using Annotations[Part - 1] Enrich CAP based Services with Behaviors using AnnotationsWalks through CDS annotations that add behaviour beyond CRUD: @readonly and @insertonly take away write, update or delete on an entity or element, each shown with the OData metadata it generates. @mandatory, @assert.unique, @assert.integrity, @assert.format and @assert.range then enforce input checks that @sap/cds runs on write, with the SQL or HANA constraint @assert.unique compiles to and the error code each rejection returns. It names @restrict and @requires but defers them, calling authorization too large a topic for this post.published 2023-01-28
Getting started with cds.ql in NodeJS for CAP - 101 on how to query dataGetting started with cds.ql in NodeJS for CAP - 101 on how to query dataWalks through cds.ql, the query API @sap/cds gives a Node.js CAP service's custom handlers, with worked SELECT, UPDATE, DELETE and INSERT examples against a sample schema — filters, AND/OR conditions, column projections, ordering, limiting, grouping and joining two entities through a schema view. An added correction notes that cds.tx(req) is no longer needed to run a query in newer CAP versions, contradicting the post's own original guidance.published 2022-06-21
CAP is important because it's not importantCAP is important because it's not importantAn essay rather than a technique: what CAP actually is, what it gives you, and the case for treating it as foundational precisely because it is not the interesting part of an application. Written in 2019, when that argument still had to be made, and the title is the argument. Also recorded as a Tech Aloud podcast episode and a CodeTalk, both linked from the post.published 2019-11-06
SAP Cloud Application Programming Model (CAP) - start hereSAP Cloud Application Programming Model (CAP) - start hereThe orientation post for CAP, published in 2018 and revised in 2020 and again in 2021 with help credited to Iwona Hahn — which is the unusual part: a starting-point index that was maintained rather than left to rot, and says so at the top. Read as the shape of what a newcomer was pointed at, and as a marker of how much of that changed inside three years.published 2018-10-10
Everything new: Try out the latest features in CAPEverything new: Try out the latest features in CAPCAP (@sap/cds) gains the features this hands-on session works through: declarative constraints, which is the input validation concern, status flows as status transition flows, a cds REPL, extensibility through @sap/cds-oyster, and HCQL, which SAP's abstract calls CAP's native query-over-HTTP protocol, after an opening stretch of AI-driven app development. The abstract names the features and stops there; what each one does is not described. A TechEd 2026 hands-on session (Wednesday 28 October, Berlin), presented by Daniel Hutzel, Daniel Schlachter, Marc Huber and Tim Back, written here from SAP's abstract; the recording is not yet published.
AI needs a foundation: A map of the plug-in ecosystem for CAPAI needs a foundation: A map of the plug-in ecosystem for CAPA map of the plug-ins for CAP (@sap/cds), official, community and independent, drawn across regions such as integration, performance and tooling, so that a team can see what exists to reuse and what it would have to build: the question plugin authoring answers from the other side. SAP's abstract places CAP at the centre of its AI strategy, with model context protocol support, and the map is offered as the foundation under that. A TechEd 2026 session (Tuesday 27 October, Community Theater, Berlin), presented by Mike Zaschka, written here from SAP's abstract; the recording is not yet published.
Learn how to define constraints declaratively in your CDS modelLearn how to define constraints declaratively in your CDS modelConstraints expressed in the model rather than checked in a handler — the distinction the atlas draws between input validation the framework enforces and validation somebody writes.SAP
What's new in SAP Cloud Application Programming Model – January 2026What's new in SAP Cloud Application Programming Model – January 2026December and January together: the new @assert feature, revised documentation, CDS editor work, and Kyma deployment additions.published 2026-02-09
What's new in SAP Cloud Application Programming Model – November 2025What's new in SAP Cloud Application Programming Model – November 2025The November edition, led by the Status Transition Flows feature presented at reCAP 2025.published 2025-12-08
What's new in SAP Cloud Application Programming Model – September 2025What's new in SAP Cloud Application Programming Model – September 2025The monthly release communication for CAP itself, and this edition carries the MCP servers and the Application Frontend Service integration. Kept because a dated list of what shipped when is the only record of that; three editions are indexed here rather than the whole run.published 2025-10-14
What's new in SAP Cloud Application Programming Model – September 2026What's new in SAP Cloud Application Programming Model – September 2026The September 2026 release turns CAP services into A2A-callable agents through the new @cap-js/agents plugin, which generates MCP tools from a service's entities and actions, adds an @agent.hitl approval gate and can read an AGENTS.md/SKILL.md pair for custom behaviour. The @cap-js/mcp plugin for Node.js and com.sap.cds:cds-adapter-mcp for Java reach general availability, serving describe, query and call tools over existing CAP authentication and authorisation. It also names capire/skills, SAP's curated skill library that teaches coding agents current CAP practice.published 2026-09-24
Boost your CAP Development with AI: Introducing the MCP Server for CAPBoost your CAP Development with AI: Introducing the MCP Server for CAPThe announcement of the development-tool half of the two things called MCP here: a server that gives an agent context about the project in front of it and relevant CAP examples, so Claude Code or Copilot steers better. Names the agents it was tried with, which is more than most announcements do.published 2025-09-03
Tree-Table Support in CAP is Now Generally AvailableTree-Table Support in CAP is Now Generally AvailableThe announcement that closes a gap other posts here worked around for years — hierarchy maintenance for Java in February, recursive support in March, generally available since July. Read it beside the 2022 post that had to build hierarchies by hand.published 2025-09-01
Product Updates for SAP Build Code – June 2025 EditionProduct Updates for SAP Build Code – June 2025 EditionThe Q2-2025 release of SAP Build Code adds a Joule-based SAP HANA Application Migration Assistant extension that automates converting XS Classic and XS Advanced service-layer artifacts — XSJSLIB, XSODATA and XSJS — into CAP service definitions and handlers on SAP HANA Cloud, extending the existing database migration assistant with generative AI. It walks through the "XS Classic to CAP" and "XS Advanced to CAP" templates that trigger the conversion.published 2025-06-27
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@sap/cdsartifact
Input validationcapability, core and community
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- explains → applies_to on capability:input-validationDoor scope derived from the artifacts this piece also explains, so a door page lists it only where it holds (docs/concepts/content-on-doors.md).
- Entered the atlasDiscovered via SAP Community · cap-tag.
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