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[Part – 2] Enrich CAP based Services with Behaviors using Annotations
The second half of a two-part walkthrough of CAP's behavioral annotations, following on from access control and input validation in the first part. This post works through @cds.autoexpose, @cds.api.ignore, @cds.persistence.exists/skip, @cds.on.insert/@cds.on.update and the @odata.Type/@odata.singleton mapping overrides, all shaping how a CDS model is projected into a service, which is data modellingData modellingDefining the shape of data before anything serves it: entities and their types, how they relate, and the projections and views that services and applications consume.SAP and community, unassessed. Alongside these it covers @cds.query.limit for default and maximum page sizes (pagination and streamingPagination and streamingReturning results a client can consume without loading everything — server-driven paging, and streaming large binaries rather than buffering them.SAP only), @odata.etag with exclusive and shared locks for optimistic concurrency (concurrency controlConcurrency controlStopping two people who opened the same record from silently overwriting each other — detecting that the version you read is no longer the version you are saving over.SAP and community, unassessed), and @cds.search for scoping $search to chosen elements (searchSearchFree-text search across an entity and its compositions, pushed into the database rather than filtered in the service. Declared search, database similarity search and filtering in application code are often lumped together.SAP and community, unassessed), each with a CDS code example.
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Data modellingData modellingDefining the shape of data before anything serves it: entities and their types, how they relate, and the projections and views that services and applications consume.Pagination and streamingCAPPagination and streamingReturning results a client can consume without loading everything — server-driven paging, and streaming large binaries rather than buffering them.Concurrency controlCAPConcurrency controlStopping two people who opened the same record from silently overwriting each other — detecting that the version you read is no longer the version you are saving over.SearchSearchFree-text search across an entity and its compositions, pushed into the database rather than filtered in the service. Declared search, database similarity search and filtering in application code are often lumped together.
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Lukas SchwabeLukas SchwabeWrote this
In the atlas: contributes to 1, wrote 2@pandayoauthor
In the atlas: contributes to 1, wrote 2@pandayoauthor
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SAP Table to CDS Mapper - New Version thanks to AI-supported DevelopmentSAP Table to CDS Mapper - New Version thanks to AI-supported DevelopmentThe author ran a table-to-CDS field analysis across a whole SAP S/4HANA 2025 FPS01 system and published the result as one HTML report, SAP Table to CDS Mapper, that ranks candidate CDS objects for a classic table or field. The post states what the snapshot holds, how the official successor, C1 release and direct coverage are ranked, and that each candidate is a lead to validate before relying on it. It credits cdsanalyser as the idea and implementation it builds on, and offers a classification import for Project Kernseife.LBretschneider, published 2026-10-26
CDS Associations & JoinsCDS Associations & JoinsA Devtoberfest 2026 session from SAP's performance and scalability team on what an ABAP CDS association becomes on SAP HANA, taken as an excerpt from their internal performance training. The CDS edge rests on the three ways an association is used: a path expression and an explicit join both put a left outer join into the generated view, while exposing the association leaves the view without one and adds the join only for a query that asks for its fields, which the session calls join on demand. The data modelling edge is the advice that follows and the demo under it — cardinality written as precisely as the data allows, because the optimiser trusts it, shown with a view whose missing cardinality let SELECT COUNT(*) prune the join and return 18 rows where selecting the columns returned 56, plus the left-hand, right-hand and left-outer-to-inner rewrites that correct cardinalities make possible.SAP Developers, published 2026-10-12
052: 10 Minutes from Start to Launchpad052: 10 Minutes from Start to LaunchpadWalks a RAP application from a root CDS view entity through a consumption projection and its associations to a metadata extension: a facet per field group, a hidden field via UI.hidden, and a selection field on the ABAP package, all in a Customer-layer DDLX source read by the generated Fiori elements app. It then covers the parts ABAP CDS modelling and annotation stop short of — service definition and binding, generating the UI in Business Application Studio, and wiring the deployed app into the Fiori Launchpad through an IAM App and business catalog.Björn S., published 2026-09-07
Beyond READ_TEXT: Decoding SAPscript Long Texts (STXL) with SQLScript in CDS/AMDPBeyond READ_TEXT: Decoding SAPscript Long Texts (STXL) with SQLScript in CDS/AMDPSTXL stores a SAPscript long text as a compressed ABAP cluster container — LZ77 plus canonical Huffman — so the only official reads are READ_TEXT, one call per text, and its mass variant READ_TEXT_TABLE, both of which ship every decompressed line to the application server and stay invisible to ABAP CDS. The author reverse-engineered that on-disk format and ported the decoder into SQLScript, wrapped in an AMDP procedure and exposed through CDS table functions, turning long texts into a joinable, filterable column read directly in the database. On ABAP 7.56 a table function needs the driver-and-filter pattern shown because a parameter cannot bind to a calling column; on ABAP 7.58/S/4HANA 2023 the same result becomes a parameter-less CDS scalar function with true filter push-down.aamelin1, published 2026-08-20
Building an SAP BTP Agent Architecture from Scratch: Python + CAP + HANABuilding an SAP BTP Agent Architecture from Scratch: Python + CAP + HANAA first-person build log of a Flask orchestrator on Cloud Foundry that reduces a question to keywords, searches a Node.js service's Documents entity, and passes what it finds to Claude for a grounded answer. Getting there means learning that HANA's fuzzy .search() matches one word but not a full sentence, fixed by splitting the query into terms and merging the per-term hits, and that provisioning SAP HANA Cloud hits a database-level free-tier quota rather than an HDI-container one, with a stopped instance needing to be resumed first. It also covers @sap/cds-dk needing to sit in dependencies rather than devDependencies, since Cloud Foundry's buildpack skips the latter, before cds deploy --to hana can run as part of the push.neilaspin, published 2026-07-28
Understanding Fuzzy Search in SAP Fiori ApplicationsUnderstanding Fuzzy Search in SAP Fiori ApplicationsExplains SAP HANA Enterprise Search's fuzzy, relevance-ranked matching behind Fiori's global search bar, its exact-match Search Query Syntax operators, and how a CAP CDS project on @sap/cds tunes the gap between them with @cds.search and @Search.fuzzinessThreshold, shown on a Contracts entity's contractNumber field. Raising the threshold to 0.95 narrows that field to near-exact matches for structured identifiers such as contract numbers, while an unset field keeps HANA's default (~80%) fuzziness for broader free-text discovery.Ruchi5, published 2026-07-27
Handling Concurrent Updates in SAP CAP JavaHandling Concurrent Updates in SAP CAP JavaAlice and Bob open the same employee record; Bob saves last and quietly erases Alice's change. The lost-update problem stated concretely and then answered in CAP Java, which is the only entry here on the subject — hence the capability.Anjali_Pathak, published 2026-05-26
Deep Insert in SAP CAPM Using Composition and Fiori ElementsDeep Insert in SAP CAPM Using Composition and Fiori ElementsParent and children created in one transaction, which composition already gives you in the model — the post is about what Fiori elements does with it, and what the payload looks like when the UI sends both at once.published 2026-05-22
Calculating IBP Technical Week "Key Figure Date" in S/4HANA Using CDS ViewCalculating IBP Technical Week "Key Figure Date" in S/4HANA Using CDS ViewA custom ABAP CDS view entity, selecting from the standard I_CalendarDate view, to derive the first date of an SAP IBP "technical week" — the split IBP applies when a calendar week crosses a month boundary, a date S/4HANA does not expose natively. The calculated field is built with a case/when expression over dats_add_days, giving any calendar date's technical-week key figure date.bharatbajaj, published 2026-02-18
Building an Enterprise Application Using Fiori Elements and CAP - Part 1Building an Enterprise Application Using Fiori Elements and CAP - Part 1Part one of three, and it is all backend: the CAP service the UI will sit on. The author states the constraint the series works under — simple enough for someone new to the stack, without departing from the standard project layout.Farooq, published 2025-12-10
Semantic search in CAP (Node.js): vector embeddings and cosine similaritySemantic search in CAP (Node.js): vector embeddings and cosine similarityFinding the best semantic match for a prompt inside an entity, using local vector embeddings and cosine similarity — and the finding the author leads with is that it works without a vector database at all. Reported as experiments rather than as a pattern, which is the honest register for it: the interesting claim is how little infrastructure the simple case needs.published 2025-12-09
Create CDS Views and expose through OData service in CAPMCreate CDS Views and expose through OData service in CAPMViews defined in CDS and then exposed, which is the whole of what a small CAP service is. Written step by step from cds init onward in Business Application Studio.VenkateshMundru, published 2025-08-11
A CAP Plugin for Flexible Number Range Management: cds-numberrange-pluginA CAP Plugin for Flexible Number Range Management: cds-numberrange-pluginThe author's own plugin, and the reason given for writing it is about plugins rather than about number ranges: a year of using them convinced them that this was the way to extend CAP without leaving marks on the application. Sequential document numbers are the thing it does; keeping the host project clean is the thing it argues for.abdulbasit, published 2025-06-17
Understanding Projections in CAPM: Select Only What You Need!Understanding Projections in CAPM: Select Only What You Need!One concept, explained by someone who had just learned it and says so — what a projection is, why it matters, and an analogy. The register is unusual here and suits the subject: projections are the first thing that makes CDS feel different from a table.Avisek_, published 2025-06-10
Generating Adobe Form Using RAP framework OData ServicesGenerating Adobe Form Using RAP framework OData ServicesModels a RAP root view entity and consumption view over a custom sales-order table, built with ABAP CDS, and exposes it through a service definition and an OData V2 UI service binding. A separate SEGW project implements GET_STREAM to call an Adobe Form driver class and stream the rendered PDF back as the response, with a computed link field added to the CDS view so the UI can open it. The PDF is generated in the backend and returned to the calling program rather than sent straight to a printer.Megastar, published 2025-03-18
My CAP Projects ToolboxMy CAP Projects ToolboxA working inventory of daily CAP tooling: scaffolding a project with cds init and growing it facet by facet through cds add (TypeScript, seed data, an .http test file, a handler stub), then running it with cds watch and setting a breakpoint in a custom handler from SAP Business Application Studio's JavaScript Debug Terminal. It also walks through an @open entity that accepts properties the model never declared, and reading temporal data defined with CAP's temporal aspect, where a plain read returns only what is valid now and a custom handler is needed to retrieve every time slice.vvdries, published 2024-12-23
SAP Incentive Management - Understanding of CSN file & CLI Command to generateSAP Incentive Management - Understanding of CSN file & CLI Command to generateCSN met from the far end: not as CAP's compiled model but as the interchange format a product hands to Analytics Cloud so a story knows the shape of the data. Explains what CSN is, why the format matters here, and the command that produces one.Yogananda, published 2024-11-19
CAP, CDS, CDL, CSN and jq - finding associationsCAP, CDS, CDL, CSN and jq - finding associationsHow associations are actually represented once CDL is compiled into CSN, worked out by parsing the machine-readable form with jq. Useful less as a recipe than as a way in: anything that wants to reason about a CDS model without the compiler has to read CSN, and this is what that looks like from the outside.published 2024-04-16
SAP CAP(Cloud Application Programming)开发框架概述SAP CAP(Cloud Application Programming)开发框架概述A Chinese-language walkthrough of CAP built mainly from CAPire's own "About CAP" page: CDS entities, associations, compositions and aspects for data modelling, with an extend Books with @restrict: [{ grant:'WRITE', to:'admin' }] aspect as its authorization example; CQL and CQN queries shown against both a local service and OData's $select/$expand; and the service-and-event model — this.on, this.emit, srv.on — that carries CAP's async processing. It closes with the author's own setup: installing @sap/cds-dk, scaffolding a bookshop project with cds init, and running it with cds watch against local SQLite, mocked authentication and file-based messaging standing in for HANA Cloud, IAS and Kafka.ArthurYang, published 2024-01-07
Use Aspects, Association and Convert OData V4 to V2 using ProxyUse Aspects, Association and Convert OData V4 to V2 using ProxyTwo halves that turn out to belong together: aspects and associations in the model, and then the v4-to-v2 proxy in front of it. The model decides what the proxy has to carry, which is why the author put them in one post.rahul_rajagopal, published 2023-08-28
#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
#BTP #SAPCAP: Quirky Nuggets (N01-N02)#BTP #SAPCAP: Quirky Nuggets (N01-N02)Walks through two CAP gotchas: the on/before/after phases of custom event handlers, shown with an after handler whose edits only reach the result when the handler returns an object or array, never a primitive; and the @assert.unique annotation, which builds a database uniqueness constraint from the model. For Input validation, the catch is that once the constrained property is nested, @assert.unique must name it by its model dot path (assignment.type) rather than the flattened column data modelling compiles it to (assignment_type).published 2023-06-05
Understanding entity relationships in CDSUnderstanding entity relationships in CDSModels a CAP task-management domain in CDS — Users, Roles, Tasks and Categories joined by to-one associations, a composition of tasks owned by a user, and a self-referencing association from a user to its parent — using the managed and cuid aspects from @sap/cds/common. It then visualises that model in Business Application Studio's CDS Graphical Modeler and adds a CAP Java before-handler that sets a generated password on user creation.Avinash_Vaidya, published 2022-11-22
Case-insensitive filters in Fiori Elements (List report + CAP)Case-insensitive filters in Fiori Elements (List report + CAP)A blocker rather than a feature: filters on a List Report are case-sensitive, the business wanted them not to be, and the CAP backend is where it gets fixed. Node and Java both.Kishannaicker, published 2022-04-26
SAP CAP Recent Enhancements the HANA Dev Should Know AboutSAP CAP Recent Enhancements the HANA Dev Should Know AboutThomas Jung walks through CAP features for HANA database developers that landed through late 2021: doc comments in the data model (CDL comments propagated into generated database objects via the package.json cdsc.docs compiler option), and schema evolution reaching general availability in the November 2021 release, using the @cds.persistence.journal annotation and cds.hana.journal settings to generate incremental hdbmigrationtable migration scripts instead of dropping and recreating tables. It also walks through two features outside those two: window functions in view column definitions, added in the December 2021 release, and a beta assert_integrity setting that generates database foreign-key constraints from 1:1 associations and compositions.published 2022-02-15
SAP CAP Adapter to expose OData as custom REST ServiceSAP CAP Adapter to expose OData as custom REST ServiceWalks through consuming an external OData V2 service in a CAP project — cds import converts the Northwind service's EDMX into a CSN and cds.connect.to wires up the remote proxy — then re-exposing it as plain REST with the @protocol:'rest' annotation instead of OData's own envelope. Shows two ways to reshape the response, renaming and dropping fields in a CDS projection or rewriting the returned objects in a custom service handler, and remaps ?pageSize and ?offset onto OData's $top and $skip in that same handler.Former Member, published 2021-09-15
Improved Search Performance in SAP BTP Core, SAP Cloud Application Programming Model, Node.js RuntimeImproved Search Performance in SAP BTP Core, SAP Cloud Application Programming Model, Node.js RuntimeExplains CDS version 5's @cds.search annotation, which lets a service declare which elements a search query covers, and states that only String-typed elements are searched by default so the generated SQL stays simple. Covers two further changes to @sap/cds's Node.js runtime: metadata about which elements are searchable is now cached, and search over localized text can resolve at query time instead of through a compiled view, avoiding a coalesce function that blocks filter push-down on SAP HANA. Also describes an experimental toggle, cds.env.features.optimized_search, that lets the runtime choose the CONTAINS predicate over LIKE for large data sets.published 2021-08-18
Creating structured types, enums and named aspects using the CDS Graphical ModelerCreating structured types, enums and named aspects using the CDS Graphical ModelerThe modelling constructs that are awkward to draw — structured types, enums, named aspects — done in the graphical modeller rather than in CDL.Xiao-fei_Song, published 2021-05-26
Importing @sap/cds common.cds to your CAP project using the CDS Graphical ModelerImporting @sap/cds common.cds to your CAP project using the CDS Graphical ModelerPulling the common aspects and code lists from @sap/cds into a model through the modeller, so the reuse types appear in the diagram rather than only in the file.Xiao-fei_Song, published 2021-05-06
First Java Cap ApplicationFirst Java Cap ApplicationA step-by-step walkthrough of a first CAP Java project: com.sap.cds:cds-services-archetype scaffolds the initial Maven project, and the domain model is then rewritten in the db folder with entities, the cuid and managed aspects, associations, compositions and a CodeList, so a hand-coded event handler serving a single entity gives way to a service that CAP's generic persistence handling serves without custom code. It deploys that model to SQLite for local development — cds deploy --to sqlite, then a Spring profile pointing at the generated database file — and ends by adding an index.cds so the model and service can be published as a reusable npm module.bruce_wang3, published 2020-12-08
Developing Business Services with Cloud Application Programming(CAP) Model in SAP Business StudioDeveloping Business Services with Cloud Application Programming(CAP) Model in SAP Business StudioA step-by-step build of a CAP Node.js service in SAP Business Application Studio: a CDS schema for banks, customers, accounts and transactions using compositions, associations, enumerated types and the @assert.unique constraint, followed by authorization layered on with @restrict and @requires annotations and mock users assigned the authenticated-user and Manager roles in .cdsrc.json. Custom event handlers registered through @sap/cds (srv.before/srv.after) and sample HTTP requests round out the example.Ranjith, published 2020-05-27
Computed field example in CAPComputed field example in CAPAn answer to a Community question — how to count the entities on the far side of an association — written up as a short post rather than left in a thread. The answer combines CDS with Node.js service events, which is the seam worth noticing: some of what looks like modelling is expressed in the model and some has to be computed when the request arrives, and the boundary between them is not obvious from either side.published 2019-08-21
Computed field example in CAP
Data modelling has changed 3 times since this was published, most recently in @sap/cds 9.9.0, 2026-04-23. Affects A recipe, Runnable code.
SAP Cloud Platform Backend service: Tutorial [11]: CDS : magic: key: generationSAP Cloud Platform Backend service: Tutorial [11]: CDS : magic: key: generationExplains CDS's UUID key type: giving a key property UUID gets its value generated automatically instead of a hand-picked unused number, as data modelling lets an element's type do, at the cost of a 36-character value unfit for a user-facing display. It then works out how that generated value is addressed in a single-entity read URL — bare brackets in OData V4 against the guid'...' literal V2 requires — citing the OData specification for the difference.CarlosRoggan, published 2019-03-15
Develop a full stack Business application with SAP Cloud Application Programming ModelDevelop a full stack Business application with SAP Cloud Application Programming ModelBuilds a full-stack CAP application in SAP Web IDE Full Stack's now-retired 'SAP Cloud Platform Business Application' template: a data-model.cds entity with its own service definition, then Fiori annotations on the generated OData. Building the project compiles that model into Catalog.xml and csn.json, the EDMX and CSN that metadata publishing says every exposed service gets. The entity and service definitions it writes by hand are the basic shape data modelling covers, though the webIDE and MTA tooling staged around them is gone.former_member584731, published 2018-11-29
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
Explore the declarative power of status-transition flowsExplore the declarative power of status-transition flowsModelling which state a record may move to next, declaratively, rather than scattering the rule across the handlers that move it.SAP
Analyze and optimize ABAP Cloud model apps built on core data servicesAnalyze and optimize ABAP Cloud model apps built on core data servicesPerformance anti-patterns in data models built with ABAP CDS under ABAP Cloud applications, and the tools that find them: the abstract names ABAP cross trace, the SQL analyzer (PlanViz) in Visual Studio Code and the SAP HANA database explorer as what the session uses to follow a bottleneck from the application to the database. The anti-patterns are taken from real business applications, which is where the data modelling edge holds; which ones are shown is not in the abstract. A TechEd 2026 session (Tuesday 27 October, Berlin), presented by Ingo Braeuninger, Robert Werlich, Steffen Siegmund and Thomas Fiedler, written here from SAP's abstract; the recording is not yet published.
#BTP #SAPCAP: Quirky Nuggets (N05-N06)#BTP #SAPCAP: Quirky Nuggets (N05-N06)On SAP BTP, Cloud Foundry Runtime, a one-shot PostgreSQL db-deployer app can be restarted by the platform's default port-type health check inside its 60-second timeout, re-running the deploy and duplicating data in the PostgreSQL database; setting health-check-type to process or http, via cf commands or the app's mta.yaml parameters, avoids it. In CAP, a remote service's entities are imported and consumed through cds.connect.to and queried via a projection, but its functions and actions cannot be projected: they must be redefined in the consuming service's own interface, with the handler forwarding the call to the remote proxy.published 2023-07-27
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Data modellingcapability, core and community
Pagination and streamingcapability, core only
Concurrency controlcapability, core and community
Searchcapability, core and community
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