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renejeglinsky merged 1 commit into from
Jun 3, 2025
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Internal CdsJsonConverter documentation #1883

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68 changes: 35 additions & 33 deletions java/cds-data.md
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Expand Up @@ -21,44 +21,44 @@ uacp: Used as link target from Help Portal at https://help.sap.com/products/BTP/

The [predefined CDS types](../cds/types) are mapped to Java types and as follows:

| CDS Type | Java Type | Remark |
|--------------------|------------------------|--------------------------------------------------------------------------|
| `cds.UUID` | `java.lang.String` | |
| `cds.Boolean` | `java.lang.Boolean` | |
| `cds.UInt8` | `java.lang.Short` | |
| `cds.Int16` | `java.lang.Short` | |
| `cds.Int32` | `java.lang.Integer` | |
| `cds.Integer` | `java.lang.Integer` | |
| `cds.Int64` | `java.lang.Long` | |
| `cds.Integer64` | `java.lang.Long` | |
| `cds.Decimal` | `java.math.BigDecimal` | |
| `cds.DecimalFloat` | `java.math.BigDecimal` | deprecated |
| `cds.Double` | `java.lang.Double` | |
| `cds.Date` | `java.time.LocalDate` | date without a time-zone (year-month-day) |
| `cds.Time` | `java.time.LocalTime` | time without a time-zone (hour-minute-second) |
| `cds.DateTime` | `java.time.Instant` | instant on the time-line with _sec_ precision |
| `cds.Timestamp` | `java.time.Instant` | instant on the time-line with _µs_ precision |
| `cds.String` | `java.lang.String` | |
| `cds.LargeString` | `java.lang.String` | `java.io.Reader` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `cds.Binary` | `byte[]` | |
| `cds.LargeBinary` | `byte[]` | `java.io.InputStream` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `cds.Vector` | `com.sap.cds.CdsVector`| for [vector embeddings](#vector-embeddings) |
| CDS Type | Java Type | Remark |
| ------------------ | ----------------------- | ------------------------------------------------------------------------ |
| `cds.UUID` | `java.lang.String` | |
| `cds.Boolean` | `java.lang.Boolean` | |
| `cds.UInt8` | `java.lang.Short` | |
| `cds.Int16` | `java.lang.Short` | |
| `cds.Int32` | `java.lang.Integer` | |
| `cds.Integer` | `java.lang.Integer` | |
| `cds.Int64` | `java.lang.Long` | |
| `cds.Integer64` | `java.lang.Long` | |
| `cds.Decimal` | `java.math.BigDecimal` | |
| `cds.DecimalFloat` | `java.math.BigDecimal` | deprecated |
| `cds.Double` | `java.lang.Double` | |
| `cds.Date` | `java.time.LocalDate` | date without a time-zone (year-month-day) |
| `cds.Time` | `java.time.LocalTime` | time without a time-zone (hour-minute-second) |
| `cds.DateTime` | `java.time.Instant` | instant on the time-line with _sec_ precision |
| `cds.Timestamp` | `java.time.Instant` | instant on the time-line with _µs_ precision |
| `cds.String` | `java.lang.String` | |
| `cds.LargeString` | `java.lang.String` | `java.io.Reader` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `cds.Binary` | `byte[]` | |
| `cds.LargeBinary` | `byte[]` | `java.io.InputStream` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `cds.Vector` | `com.sap.cds.CdsVector` | for [vector embeddings](#vector-embeddings) |

### SAP HANA-Specific Data Types

To facilitate using legacy CDS models, the following [SAP HANA-specific data types](../advanced/hana#hana-types) are supported:

| CDS Type | Java Type | Remark |
| --- | --- | --- |
| `hana.TINYINT` | `java.lang.Short` | |
| `hana.SMALLINT` | `java.lang.Short` | |
| `hana.SMALLDECIMAL` | `java.math.BigDecimal` | |
| `hana.REAL` | `java.lang.Float` | |
| `hana.CHAR` | `java.lang.String` | |
| `hana.NCHAR` | `java.lang.String` | |
| `hana.VARCHAR` | `java.lang.String` | |
| `hana.CLOB` | `java.lang.String` | `java.io.Reader` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `hana.BINARY` | `byte[]` | |
| CDS Type | Java Type | Remark |
| ------------------- | ---------------------- | ------------------------------------------------------------------- |
| `hana.TINYINT` | `java.lang.Short` | |
| `hana.SMALLINT` | `java.lang.Short` | |
| `hana.SMALLDECIMAL` | `java.math.BigDecimal` | |
| `hana.REAL` | `java.lang.Float` | |
| `hana.CHAR` | `java.lang.String` | |
| `hana.NCHAR` | `java.lang.String` | |
| `hana.VARCHAR` | `java.lang.String` | |
| `hana.CLOB` | `java.lang.String` | `java.io.Reader` <sup>(1)</sup> if annotated with `@Core.MediaType` |
| `hana.BINARY` | `byte[]` | |


> <sup>(1)</sup> Although the API to handle large objects is the same for every database, the streaming feature, however, is supported (and tested) in **SAP HANA**, **PostgreSQL**, and **H2**. See section [Database Support in Java](./cqn-services/persistence-services#database-support) for more details on database support and limitations.
Expand Down Expand Up @@ -275,6 +275,8 @@ person.toJson(); // { "salutation" : "Mr.", name : { "first" : "Frank" } }
Avoid cyclic relationships between CdsData objects when using toJson.
:::

<div id="cdsdata-serialization-jsonconverter"/>


## Vector Embeddings <Beta /> { #vector-embeddings }

Expand Down