feat(rest): Add common `serialization` utils

src/status_node_manager/rest/rest_serialization.nim

@@ -0,0 +1,87 @@
+import std/[strutils, algorithm, sets, strformat]
+import chronos, chronos/apps, chronos/unittest2/asynctests, stew/byteutils,
+       metrics,
+       nimcrypto
+import presto/[route, segpath, server, client]
+import json_serialization/std/[net, sets],
+       json_serialization/stew/results as jsonSerializationResults,
+       serialization, json_serialization
+
+const ApplicationJsonMediaType* = MediaType.init("application/json")
+
+createJsonFlavor RestJson
+
+RestJson.useDefaultSerializationFor(
+  auto
+  )
+
+type
+  DecodeTypes* =
+    auto
+
+type
+  EncodeTypes* =
+    auto
+
+proc encodeBytes*[T: EncodeTypes](value: T,
+                                  contentType: string): RestResult[seq[byte]] =
+  case contentType
+  of "application/json":
+    let data =
+      block:
+        try:
+          var stream = memoryOutput()
+          var writer = JsonWriter[RestJson].init(stream)
+          writer.writeValue(value)
+          stream.getOutput(seq[byte])
+        except IOError:
+          return err("Input/output error")
+        except SerializationError:
+          return err("Serialization error")
+    ok(data)
+  else:
+    err("Content-Type not supported")
+
+proc decodeBytes*[T: DecodeTypes](t: typedesc[T],
+                                  value: openArray[byte],
+                                  contentType: Opt[ContentTypeData]
+    ): RestResult[T] =
+
+  let mediaType =
+    if contentType.isNone():
+      ApplicationJsonMediaType
+    else:
+      if isWildCard(contentType.get().mediaType):
+        return err("Incorrect Content-Type")
+      contentType.get().mediaType
+
+  if mediaType == ApplicationJsonMediaType:
+    try:
+      ok RestJson.decode(value, T,
+                         requireAllFields = true,
+                         allowUnknownFields = true)
+    except SerializationError as exc:
+      debug "Failed to deserialize REST JSON data",
+            err = exc.formatMsg("<data>"),
+            data = string.fromBytes(value)
+      err("Serialization error")
+  else:
+    err("Content-Type not supported")
+
+proc decodeBody*[T](t: typedesc[T],
+                    body: ContentBody): Result[T, cstring] =
+  if body.contentType != ApplicationJsonMediaType:
+    return err("Unsupported content type")
+  let data =
+    try:
+      RestJson.decode(body.data, T,
+                      requireAllFields = true,
+                      allowUnknownFields = true)
+    except SerializationError as exc:
+      debug "Failed to deserialize REST JSON data",
+            err = exc.formatMsg("<data>"),
+            data = string.fromBytes(body.data)
+      return err("Unable to deserialize data")
+    except CatchableError:
+      return err("Unexpected deserialization error")
+  ok(data)