---
title: Elastic.Mapping
description: Describe your Elasticsearch mapping with C# attributes. A source generator turns those declarations into component template JSON at compile time, so you...
url: https://docs-v3-preview.elastic.dev/elastic-ingest-dotnet/mapping
---

# Elastic.Mapping
Describe your Elasticsearch mapping with C# attributes. A source generator turns those declarations into component template JSON at compile time, so you never write mapping JSON by hand.
```csharp
public class Product
{
    [Id]
    [Keyword]
    public string Sku { get; set; }

    [Text(Analyzer = "standard")]
    public string Name { get; set; }

    [Keyword]
    public string Category { get; set; }
}

[ElasticsearchMappingContext]
[Index<Product>(Name = "products")]
public static partial class MyContext;
```

From this declaration, the source generator produces all the JSON, hashes, and metadata that `Elastic.Ingest.Elasticsearch` needs to create templates, send bulk requests, and manage indices.

## Install

```shell
dotnet add package Elastic.Ingest.Elasticsearch
```

This pulls in `Elastic.Mapping` (with the bundled source generator) and `Elastic.Channels` as transitive dependencies.

## What happens at compile time

```mermaid
flowchart LR
    A["Document class\n+ field attributes"] --> B["Source generator"]
    C["Context class\n+ Index, DataStream"] --> B
    D["ConfigureAnalysis\nConfigureMappings"] --> B
    B --> E["Mappings JSON"]
    B --> F["Settings JSON"]
    B --> G["Accessor delegates\n(GetId, GetTimestamp)"]
    B --> H["Content hash"]
    E --> I["Component template"]
    F --> I
    G --> J["Bulk operations"]
    H --> K["Change detection"]
```

The generator:
- Finds classes marked with `[ElasticsearchMappingContext]`
- Reads each `[Index<T>]`, `[DataStream<T>]`, or `[WiredStream<T>]` registration
- Walks the document type's properties to infer Elasticsearch field types
- Parses any `ConfigureAnalysis` / `ConfigureMappings` methods
- Emits a partial context class with everything the ingest channel needs

<dropdown title="What exactly gets generated?">
  For each type registration, the generator emits:
  - **Mappings JSON** for the component template `properties` section
  - **Settings JSON** with shards, replicas, refresh interval
  - **Combined SHA-256 hash** for change detection (skips template updates when unchanged)
  - **Accessor delegates** like `GetId`, `GetTimestamp`, `GetContentHash`, `SetBatchIndexDate`
  - **Index/search strategy metadata** with write target, date pattern, data stream name, aliases
  - **ConfigureAnalysis delegate** wired to your analysis configuration method
  - **MappingsBuilder extensions** with strongly-typed per-property fluent methods
  - **Analysis name accessors** for compile-time verified analyzer/tokenizer/filter references
</dropdown>