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SAP Cloud Platform Backend service: Tutorial [11]: CDS : magic: key: generation
Explains CDS's UUID key type: giving a key property UUID gets its value generated automatically instead of a hand-picked unused number, as 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 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 ODataODataExposing data and operations through OData, including the service model, metadata and protocol versions clients require. Version differences affect which clients can consume a service and which query features they can use.SAP and community, narrow by design V4 against the guid'...' literal V2 requires — citing the OData specification for the difference.
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Explains
Data modellingCAPData 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.ODataCAPODataExposing data and operations through OData, including the service model, metadata and protocol versions clients require. Version differences affect which clients can consume a service and which query features they can use.
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Data modelling has changed 3 times since this was published, most recently in @sap/cds 9.9.0, 2026-04-23
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Who is behind it
CarlosRogganauthor
Before you read it
ApplicabilityCore changedData modelling has changed 3 times since this was published, most recently in @sap/cds 9.9.0, 2026-04-23.
This is a derived prompt to re-check the work, not a claim that the work is wrong. Exact stale statements are recorded separately after editorial review.
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For data-modelling
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For odata
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Group by37 of 37 pieces
Piece, what it offersStill applies
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
Adding Immutable Blockchain Proofs to SAP With CAP - Cardano and OData V4Adding Immutable Blockchain Proofs to SAP With CAP - Cardano and OData V4The write-up behind ODATANO, by its author: how a public blockchain gets reachable from CAP as an ordinary OData V4 service rather than through a bespoke client. The premise it starts from is worth the read on its own — SAP systems are trusted but mutable, which is what an immutable anchor is for — and Cardano is chosen for peer-reviewed research and formal methods rather than for popularity. Written as an experiment with feedback invited, not as a recommendation.maxalexweber, published 2026-05-15
UI for the BTP Application Vulnerability ReportUI for the BTP Application Vulnerability ReportAn open-source SAPUI5 front end for SAP's Application Vulnerability Report API, backed by a CAP Node.js service that projects the external findings as an OData V4 entity and forwards each query with api.run(req.query). The CAP service reaches that API through a Destination service instance configured with OAuth2ClientCredentials authentication from a service key, so the address and credentials stay out of the application code.published 2026-02-10
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
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
The Complete Guide to Calling Actions in UI5 with Custom CodeThe Complete Guide to Calling Actions in UI5 with Custom CodeWritten because the documentation is thin and the samples sparse, and openly as a note to the author's future self — hand-coding an action call has become a rare task for anyone mostly working in Fiori elements, which is exactly why it is hard to look up when it comes round. Comes with a CAP sample project, so the service half is there too.published 2025-07-21
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
How to Perform Initial Loads from S/4HANA to Advanced Event Mesh with Odata PollHow to Perform Initial Loads from S/4HANA to Advanced Event Mesh with Odata PollWalks through building a Cloud Integration flow that polls the S/4HANA Business Partner OData API on a timer, splits the response into individual records, and publishes each as an event to Advanced Event Mesh through its adapter, with the topic set dynamically from a grouping property. Selects fields and expands associations with $select/$expand against an EDMX from the API Business Hub, and works around the OData V2 adapter's lack of JSON support by falling back to the HTTP adapter with an XML-to-JSON converter. Flags the trade-off: the pattern needs no backend change beyond activating the API, but the polled payload has to stay aligned with whatever event format the ERP pushes on change.AlexPfeil, published 2025-04-04
Calling bound / unbound CAP actions from Fiori elements application.Calling bound / unbound CAP actions from Fiori elements application.invokeAction from the Fiori elements Edit flow API, with the difference between bound and unbound actions spelled out first because the call shape differs. Under three thousand characters and it answers exactly one question.vidhyasagarmule, published 2024-09-07
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
#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 (N03-N04)#BTP #SAPCAP: Quirky Nuggets (N03-N04)Two unrelated findings in one post, which is the format of the series: the OData operators tried against a CAP service — with a schema of deliberately awkward types to try them on — and undeploying database artifacts, which is the half people hit in anger. Numbered N03 and N04 of a run that continues either side.Ajit_K_Panda, published 2023-06-05
#BTP #SAPCAP: Quirky Nuggets (N03-N04)
Deployment changed in @sap/cds-dk 8.9.0, 2025-03-31. Affects A recipe, Runnable code.
SAP CAP function and action with Unstructured/Dynamic Type Input/OutputSAP CAP function and action with Unstructured/Dynamic Type Input/OutputA CAP action or function can take or return an unstructured type: annotate the service @protocol: 'rest', declare the parameter or return value as @open type object {}, and a handler shapes the payload however a given request needs, shown here with a bound action and a function that returns a different structure per input. The text states plainly that OData V4 and GraphQL services require a fixed structure for action and function parameters, so the dynamic type works only over CAP's REST protocol.published 2022-12-08
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsMessaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsGetting a message out of a CAP service and onto a Fiori elements object page in a draft scenario — errors, warnings and information, each of which the UI treats differently. Co-written with one of the people on the OData side, and it spends its length on the message container rather than on the handler that fills it.arley-triana-morin, published 2022-08-11
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client Applications
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe, Runnable code.
Extend SAP SuccessFactors on SAP BTP with CAP - Create the CAP ServiceExtend SAP SuccessFactors on SAP BTP with CAP - Create the CAP ServiceWalks through writing a service definition in SAP Business Application Studio that projects entities from an existing CDS model: one entity gets @odata.draft.enabled because Fiori Elements only shows CRUD actions on a draft-enabled entity, and a read-only projection of an already-imported SuccessFactors OData entity fails with the generic handlers because the call is delegated to the remote service, so a custom handler is needed. Running cds watch then serves the entities, drafts and $metadata at the declared service path.published 2022-03-23
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
Create a Business Service using CDS, Node.js, SQLite and a OData serviceCreate a Business Service using CDS, Node.js, SQLite and a OData serviceThe stack at its smallest — CDS, Node, SQLite, an OData service — worked through at length. Nothing cloud in it, which is the point: it is the shape of a CAP service before any of the platform arrives.raybanton, published 2021-07-12
Create a Business Service using CDS, Node.js, SQLite and a OData service
Database connectors has changed twice since this was published, most recently in @sap/cds 10.1.0, 2026-09-07. Affects A recipe, Runnable code.
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
The End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single ProjectThe End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single ProjectOne CAP service exposing OData V2, OData V4 and REST at the same time, which is unusual enough to be worth the read on its own. Part of an end-to-end series, deployed on Cloud Foundry against HANA Cloud, so the protocol question sits inside a whole application rather than a snippet.KRiedelsheimer, published 2021-05-06
The End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single Project
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe, Runnable code.
Custom Functions in OData V4 – SAP Cloud Application Programming ModelCustom Functions in OData V4 – SAP Cloud Application Programming ModelFunctions rather than actions, and the distinction is where it starts: a function must return data and must never change any, so it is the read-only half of custom operations. Then how to declare and implement one on a CAP service.Roopa_N, published 2021-04-28
Custom Functions in OData V4 – SAP Cloud Application Programming Model
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe.
SAP BTP SDK for iOS & CAP with OData V4 supportSAP BTP SDK for iOS & CAP with OData V4 supportThe iOS SDK gaining OData V4, which until then made connecting a native app to a CAP service awkward — CAP defaults to v4 and the SDK did not speak it. Short, and it marks the date that stopped being a problem.KRiedelsheimer, published 2021-04-21
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
Resolving date serialization issues when using an external OData v2 service with CAPResolving date serialization issues when using an external OData v2 service with CAPDates coming out of an external OData v2 service in a shape CAP does not expect, and what to do about it. A narrow bug report with a fix, and the kind of thing that costs an afternoon if nobody has written it down.pieterjanssens, published 2020-07-09
How to add OData v2 adapter proxy to your CAP projectHow to add OData v2 adapter proxy to your CAP projectThe problem is stated in one line — a UI5 application that only speaks OData v2 in front of a CAP service that speaks v4 — and the answer is a proxy in the middle rather than a rewrite of either end. Written while v4 support in the UI5 stack was still patchy, which is the whole reason the adapter exists.published 2020-06-30
How to add OData v2 adapter proxy to your CAP project
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects Runnable code.
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 Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDKSAP Cloud Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDKThe same thing again through SAP Cloud SDK, published as a deliberate comparison with the part before it — the author says outright that it does what the previous post did, differently. Reading both is how you see what the SDK is actually doing for you.CarlosRoggan, published 2019-07-26
SAP Cloud Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDK
Destinations changed in @sap-cloud-sdk/connectivity 4.0.0, 2025-03-04. Affects Runnable code.
SAP Cloud Application Programming Model: Deep Insert (4) Consume Remote ServiceSAP Cloud Application Programming Model: Deep Insert (4) Consume Remote ServiceFourth in a long series on deep insert, and the one where the target stops being local. Twenty thousand characters, project files linked, and the earlier parts on UUIDs and multi-level structures are prerequisites the author names.CarlosRoggan, published 2019-07-24
SAP Cloud Application Programming Model: Deep Insert (4) Consume Remote Service
Destinations changed in @sap-cloud-sdk/connectivity 4.0.0, 2025-03-04. Affects A recipe, Runnable code.
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
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.
Consume Remote Services in a Full-Stack CAP ApplicationConsume Remote Services in a Full-Stack CAP ApplicationExtending the Developer's Guide application with a remote S/4HANA service — connectivity, importing the Business Partner API, and running against it. SAP publishes this as four separate paths: mock server or real S/4HANA Cloud, times Cloud Foundry or Kyma. One entry covers all four, because the difference between them is which backend and which runtime, not what you learn.SAP
Extend SAP SuccessFactors on SAP BTP with the SAP Cloud Application Programming ModelExtend SAP SuccessFactors on SAP BTP with the SAP Cloud Application Programming ModelTwelve tutorials, about two hours, building a side-by-side extension of SuccessFactors on BTP. The spine is remote services: importing the SuccessFactors OData service definitions into a CAP model, then treating them as entities the extension reads and writes through, rather than as an API called from a handler. Indexed as one entry because the parts only make sense in order.SAP
AI-assisted full stack development using model context protocol serversAI-assisted full stack development using model context protocol serversMCP servers in Visual Studio Code used to configure, query and change a full-stack application built with CAP, CDS and OData: the agent access to your code concern, a coding assistant reading and changing the project it works in. The abstract names no server, so neither @cap-js/mcp-server nor any other is attached, and it does not say which changes are made. A TechEd 2026 session (Thursday 29 October, Berlin), presented by Sergio Guerrero, written here from SAP's abstract; the recording is not yet published.
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