feat: initial implementation for template building in FeatureTemplateLibrary class

Author: nmaarnio

arho_feature_template/core/feature_template.py

@@ -27,5 +27,12 @@ class FeatureTemplate:
     name: str
     description: str
     feature_layer: QgsVectorLayer
-    feature_attributes: Sequence[FeatureAttribute]
+    feature_attributes: Sequence[FeatureAttribute] | None = None
     display_icon: QIcon | None = None
+
+    def add_feature_attributes(self, feature_attribute_groups: Sequence[dict]):
+        for _group in feature_attribute_groups:
+            # Should we add FeatureAttributeGroup as a class? Or can group name be
+            # only one class attribute of FeatureAttribute?
+            # TODO
+            pass

arho_feature_template/core/feature_template_library.py

@@ -3,11 +3,15 @@
 import json
 from typing import TYPE_CHECKING, Sequence
 
+from qgis.core import QgsMapLayer, QgsProject, QgsVectorLayer
+from qgis.utils import iface
+
+from arho_feature_template.core.feature_template import FeatureTemplate
+from arho_feature_template.core.json_config import JsonKeys
+
 if TYPE_CHECKING:
     from os import PathLike
 
-    from arho_feature_template.core.feature_template import FeatureTemplate
-
 
 class FeatureTemplateLibrary:
     """Class for storing FeatureTemplates and loading them from a JSON (or other conf. file)."""
@@ -23,14 +27,86 @@ def read_json(self, json_path: str | PathLike) -> dict:
             return json.load(f)
 
     def build_templates(self, library_dict: dict):
+        """Build feature templates from input `library_dict` and update `templates` attribute."""
+        all_templates_count = 0
+        invalid_templates_count = 0
         templates = []
 
-        _templates_raw = library_dict["templates"]
-        # for template_raw in templates_raw:
-            ## ... build FeatureTemplate from dict here, in FeatureTemplate class or elsewhere?
-            # template = FeatureTemplate()
-            # templates.append(template)
+        templates_raw = library_dict.get(JsonKeys.TEMPLATES)
+        if not templates_raw:
+            iface.messageBar().pushWarning(
+                "Error: ", f"Could not find any templates in the template library JSON with key {JsonKeys.TEMPLATES}."
+            )
+            return
+
+        # Go through each template data in the dictionary, save info about invalid templates?
+        for template_raw in templates_raw:
+            template = self.build_feature_template(template_raw)
+            if not template:
+                invalid_templates_count += 1
+            else:
+                templates.append(template)
+            all_templates_count += 1
+
         self.templates = templates
 
+        if invalid_templates_count > 0:
+            iface.messageBar().pushWarning(
+                "Warning: ",
+                f"Failed to create {invalid_templates_count} out of {all_templates_count} \
+                feature templates from the template library JSON."
+            )
+
+    def build_feature_template(self, template_dict: dict) -> FeatureTemplate | None:
+        """
+        Attempt to build a `FeatureTemplate` from given `template_dict`.
+
+        Args:
+            template_dict: Information about a feature template as a dictionary.
+
+        Returns:
+            `FeatureTemplate` if building was successful, otherwise None.
+        """
+        name: str = template_dict.get(JsonKeys.NAME)
+        description: str = template_dict.get(JsonKeys.DESCRIPTION, "No description")
+        feature: dict = template_dict.get(JsonKeys.FEATURE, {})
+        feature_layer_name: str = feature.get(JsonKeys.LAYER, "")
+        layers = QgsProject.instance().mapLayersByName(feature_layer_name)
+        if not layers:
+            feature_layer = None
+        else:
+            feature_layer: QgsMapLayer = layers[0]
+            # Is this needed?
+            if len(layers) > 1:
+                iface.messageBar().pushWarning(
+                    "Warning: ",
+                    f"Multiple layers with the specified feature layer name {feature_layer_name} found \
+                    for feature template {name}, using the first match."
+                )
+
+            if not isinstance(feature_layer, QgsVectorLayer):
+                iface.messageBar().pushWarning(
+                    "Error: ",
+                    f"Feature layer found but has invalid type {type(feature_layer)} for feature template {name}."
+                )
+                feature_layer = None
+
+        # All information is needed for FeatureTemplate except for description?
+        if not name or not feature or not feature_layer_name or not feature_layer:
+            return None
+
+        # TODO: fields of feature layer
+        # feature_fields = feature.get(JsonKeys.FIELDS, [])
+
+        feature_template = FeatureTemplate(
+            name=name,
+            description=description,
+            feature_layer=feature_layer,
+        )
+        feature_attribute_groups = feature.get(JsonKeys.CHILDREN, [])
+        feature_template.add_feature_attributes(feature_attribute_groups)
+
+        return feature_template
+
     def get_templates(self) -> Sequence[FeatureTemplate]:
         return self.templates

arho_feature_template/core/json_config.py

@@ -0,0 +1,21 @@
+from dataclasses import dataclass
+
+
+@dataclass
+class JsonKeys:
+    VERSION = "version"
+    NAME = "name"
+    TEMPLATES = "templates"
+
+    DESCRIPTION = "description"
+    FEATURE = "feature"
+
+    LAYER = "layer"
+    FIELDS = "fields"
+    CHILDREN = "children"
+
+    FIELD = "field"
+    VALUE = "value"
+    MODIFIABLE = "allow_user_input"
+    HIDDEN = "hidden"
+    REQUIRED = "required"