fix text expansion issues

blockkit/components.py

@@ -1,51 +1,53 @@
 import json
-from typing import TYPE_CHECKING, Any, List, Type, Union
+from typing import Any, List, Type
+from typing import get_origin, get_args, get_type_hints
 
-from pydantic import BaseModel
-
-if TYPE_CHECKING:
-    from blockkit.objects import MarkdownText, PlainText
+from pydantic import BaseModel, model_validator
 
 
 class Component(BaseModel):
-    def __init__(self, *args, **kwargs):
-        for name, field in self.model_fields.items():
-            value = kwargs.get(name)
-            origin = getattr(field.annotation, "__origin__", None)
-            if (
-                value
-                and type(value) in (str, list)
-                and origin is Union
-                and self.__class__.__name__ != "Message"
-            ):
-                types = field.annotation.__args__
-                # types = field.type_.__args__
-                if type(value) is str:
-                    value = self._expand_str(value, types)
-                elif type(value) is list:
-                    items = []
-                    for v in value:
-                        if type(v) is str:
-                            v = self._expand_str(v, types)
-                        items.append(v)
-                    value = items
-
-                kwargs[name] = value
-        super().__init__(*args, **kwargs)
-
-    def _expand_str(
-        self, value: str, types: List[Type[Any]]
-    ) -> Union["PlainText", "MarkdownText", str]:
-        literal_types = [getattr(t, "__name__", None) for t in types]
-
-        if "MarkdownText" in literal_types:
-            idx = literal_types.index("MarkdownText")
-            return types[idx](text=value)
-        elif "PlainText" in literal_types:
-            idx = literal_types.index("PlainText")
-            return types[idx](text=value, emoji=True)
-
+    @model_validator(mode="after")
+    def expand_strings(self) -> Any:
+        hints = get_type_hints(self)
+        for field_name, types in hints.items():
+            inner_types = self._get_inner_types(types)
+            if not inner_types:
+                continue
+
+            value = getattr(self, field_name)
+            type_names = [t.__name__ for t in inner_types]
+
+            expandable = "MarkdownText" in type_names or "PlainText" in type_names
+            if not expandable:
+                continue
+
+            if isinstance(value, str):
+                value = self._expand_str(value, inner_types, type_names)
+            if isinstance(value, list):
+                value = [
+                    self._expand_str(v, inner_types, type_names)
+                    if isinstance(v, str)
+                    else v
+                    for v in value
+                ]
+            setattr(self, field_name, value)
+        return self
+
+    @classmethod
+    def _expand_str(cls, value: str, types: List[Type[Any]], type_names: List[str]):
+        if "MarkdownText" in type_names:
+            return types[type_names.index("MarkdownText")](text=value)
+        elif "PlainText" in type_names:
+            return types[type_names.index("PlainText")](text=value, emoji=True)
         return value
 
+    @classmethod
+    def _get_inner_types(cls, types, parent_types=None):
+        origin = get_origin(types)
+        if not origin:
+            return parent_types
+        args = get_args(types)
+        return cls._get_inner_types(args[0], parent_types=args)
+
     def build(self) -> dict:
         return json.loads(self.model_dump_json(by_alias=True, exclude_none=True))

tests/test_blocks.py

@@ -20,7 +20,7 @@
     RichTextQuote,
     RichTextSection,
 )
-from blockkit.objects import Emoji, MarkdownText, Style, Text
+from blockkit.objects import MarkdownText, Text
 from pydantic import ValidationError
 
 
@@ -411,7 +411,7 @@ def test_builds_section():
     assert Section(
         text=MarkdownText(text="*markdown* text"),
         block_id="block_id",
-        fields=[MarkdownText(text="field 1"), MarkdownText(text="field 2")],
+        fields=["field 1", MarkdownText(text="field 2")],
         accessory=Button(text=PlainText(text="button"), action_id="action_id"),
     ).build() == {
         "type": "section",

tests/test_components.py

@@ -1,7 +1,7 @@
-from blockkit.objects import Confirm
+from blockkit import Confirm, Context, Image
 
 
-def test_converts_str():
+def test_expands_str():
     assert Confirm(
         title="title",
         text="*markdown* text",
@@ -15,3 +15,30 @@ def test_converts_str():
         "deny": {"type": "plain_text", "text": "deny", "emoji": True},
         "style": "primary",
     }
+
+
+def test_expands_str_list():
+    assert Context(
+        elements=[
+            Image(image_url="http://placekitten.com/300/200", alt_text="kitten"),
+            "element 1",
+            "element 2",
+        ]
+    ).build() == {
+        "type": "context",
+        "elements": [
+            {
+                "type": "image",
+                "image_url": "http://placekitten.com/300/200",
+                "alt_text": "kitten",
+            },
+            {
+                "type": "mrkdwn",
+                "text": "element 1",
+            },
+            {
+                "type": "mrkdwn",
+                "text": "element 2",
+            },
+        ],
+    }

tests/test_surfaces.py

@@ -197,7 +197,7 @@ def test_builds_message():
         text="message text",
         blocks=[
             Section(
-                text=MarkdownText(text="*markdown* text"),
+                text="*markdown* text",
                 accessory=Button(text=PlainText(text="button"), action_id="action_id"),
             ),
             RichText(