lostluck commented on a change in pull request #15632:
URL: https://github.com/apache/beam/pull/15632#discussion_r720618557
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File path: website/www/site/content/en/documentation/programming-guide.md
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@@ -3191,13 +3264,63 @@ output_pc = input_pc | beam.Map(lambda item:
beam.Row(bank=str(item["bank"]),
purchase_amount=float(item["purchase_amount"])))
{{< /highlight >}}
+{{< paragraph class="language-go" >}}
+Beam currently only infers schemas for exported fields in Go structs.
+{{< /paragraph >}}
+
+{{< paragraph class="language-go" >}}
+**Structs**
+{{< /paragraph >}}
+
+{{< paragraph class="language-go" >}}
+Beam will automatically infer schemas for all Go structs used
+as PCollection elements, and default to encoding them using
+schema encoding.
+{{< /paragraph >}}
+
+{{< highlight go >}}
+type Transaction struct{
+ Bank string
+ PurchaseAmount float64
+
+ checksum []byte // ignored
+}
+{{< /highlight >}}
+
+{{< paragraph class="language-go" >}}
+Unexported fields are ignored, and cannot be automatically infered as part of
the schema.
+Fields of type func, channel, unsafe.Pointer, or uintptr will be ignored by
inference.
+Fields of interface types are ignored, unless a schema provider
+is registered for them.
+{{< /paragraph >}}
+
+{{< paragraph class="language-go" >}}
+By default, schema field names will match the exported struct field names.
+In the above example, "Bank" and "PurchaseAmount" are the schema field names.
+A schema field name can be overridden with a struct tag for the field.
+{{< /paragraph >}}
+
+{{< highlight go >}}
+type Transaction struct{
+ Bank string `beam:"bank"`
+ PurchaseAmount float64 `beam:"purchase_amount"`
+}
+{{< /highlight >}}
+
+{{< paragraph class="language-go" >}}
+Overriding schema field names is useful for compatibility cross language
transforms.
Review comment:
Elaborated a bit. Going to merge this in, things are generally easier to
understand in rendered form, and it's easy enough to make spot fixes later.
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