Extend json-schema model parser

Summary

For https://gitlab.indiscale.com/caosdb/customers/3dmmto/management/-/issues/9.

This implements

• pattern properties
• type null properties
• json schema references
• and json schemas without top-level recordtype specification

for the json schema datamodel parser.

Focus

Mainly additions to the JsonSchemaParser class. We also defined a treatment for type: array properties that lack a strict items specification (i.e., could be lists of elements with mixed types, so a manual specification has to be provided -- or they are ignored altogether).

Test Environment

New unit tests. You can also test it with the chemotion json schema in nextcloud/Customers/3dmmto/example_files/testdaten_chemotion/schema.json.

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Up-to-date JSON schema (or not necessary)
• Appropriate user and developer documentation (or not necessary)
  • How do I use the software? Assume "stupid" users.
  • How do I develop or debug the software? Assume novice developers.
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

src/caosadvancedtools/models/parser.py

@@ -77,7 +77,8 @@ JSON_SCHEMA_ATOMIC_TYPES = [
     "string",
     "boolean",
     "integer",
-    "number"
+    "number",
+    "null"
 ]
 
 
@@ -153,7 +154,12 @@ def parse_model_from_string(string):
     return parser.parse_model_from_string(string)
 
 
-def parse_model_from_json_schema(filename: str, top_level_recordtype: bool = True):
+def parse_model_from_json_schema(
+        filename: str,
+        top_level_recordtype: bool = True,
+        types_for_missing_array_items: dict = {},
+        ignore_unspecified_array_items: bool = False
+):
     """Return a datamodel parsed from a json schema definition.
 
     Parameters
@@ -163,7 +169,14 @@ def parse_model_from_json_schema(filename: str, top_level_recordtype: bool = Tru
     top_level_recordtype : bool, optional
         Whether there is a record type defined at the top level of the
         schema. Default is true.
-
+    types_for_missing_array_items : dict, optional
+        dictionary containing fall-back types for json entries with `type:
+        array` but without `items` specification. Default is an empty dict.
+    ignore_unspecified_array_items : bool, optional
+        Whether to ignore `type: array` entries the type of which is not
+        specified by their `items` property or given in
+        `types_for_missing_array_items`. An error is raised if they are not
+        ignored. Default is False.
 
     Returns
     -------
@@ -180,7 +193,7 @@ def parse_model_from_json_schema(filename: str, top_level_recordtype: bool = Tru
     # @author Florian Spreckelsen
     # @date 2022-02-17
     # @review Daniel Hornung 2022-02-18
-    parser = JsonSchemaParser()
+    parser = JsonSchemaParser(types_for_missing_array_items, ignore_unspecified_array_items)
 
     return parser.parse_model_from_json_schema(filename, top_level_recordtype)
 
@@ -628,6 +641,11 @@ class JsonSchemaParser(Parser):
     # @date 2022-02-17
     # @review Timm Fitschen 2022-02-30
 
+    def __init__(self, types_for_missing_array_items={}, ignore_unspecified_array_items=False):
+        super().__init__()
+        self.types_for_missing_array_items = types_for_missing_array_items
+        self.ignore_unspecified_array_items = ignore_unspecified_array_items
+
     def parse_model_from_json_schema(self, filename: str, top_level_recordtype: bool = True):
         """Return a datamodel created from the definition in the json schema in
         `filename`.
@@ -693,10 +711,19 @@ class JsonSchemaParser(Parser):
                 # Check if this is a valid Json Schema
                 name = self._stringify(elt["title"], context=elt)
                 self._treat_element(elt, name)
-            elif "properties" in elt:
-                for key, prop in elt["properties"].items():
-                    name = self._get_name_from_property(key, prop)
-                    self._treat_element(prop, name)
+            elif "properties" in elt or "patternProperties":
+                # No top-level type but there are entities
+                if "properties" in elt:
+                    for key, prop in elt["properties"].items():
+                        name = self._get_name_from_property(key, prop)
+                        self._treat_element(prop, name)
+                if "patternProperties" in elt:
+                    # See also treatment in ``_treat_record_type``. Since here,
+                    # there is no top-level RT we use the prefix `__Pattern`,
+                    # i.e., the resulting Record Types will be called
+                    # `__PatternElement`.
+                    self._treat_pattern_properties(
+                        elt["patternProperties"], name_prefix="__Pattern")
             else:
                 # Neither RecordType itself, nor further properties in schema,
                 # so nothing to do here. Maybe add something in the future.
@@ -726,6 +753,10 @@ class JsonSchemaParser(Parser):
             return db.DOUBLE
         elif elt["type"] == "boolean":
             return db.BOOLEAN
+        elif elt["type"] == "null":
+            # This could be any datatype since a valid json will never have a
+            # value in a null property. We use TEXT for convenience.
+            return db.TEXT
         else:
             raise JsonSchemaDefinitionError(f"Unkown atomic type in {elt}.")
 
@@ -741,7 +772,7 @@ class JsonSchemaParser(Parser):
         if name == "name":
             # This is identified with the CaosDB name property as long as the
             # type is correct.
-            if not elt["type"] == "string":
+            if not elt["type"] == "string" and "string" not in elt["type"]:
                 raise JsonSchemaDefinitionError(
                     "The 'name' property must be string-typed, otherwise it cannot "
                     "be identified with CaosDB's name property."
@@ -761,6 +792,9 @@ class JsonSchemaParser(Parser):
             ent = self._treat_record_type(elt, name)
         elif elt["type"] == "array":
             ent, force_list = self._treat_list(elt, name)
+        elif elt["type"] == "null":
+            # null
+            return None, force_list
         else:
             raise NotImplementedError(
                 f"Cannot parse items of type '{elt['type']}' (yet).")
@@ -769,7 +803,8 @@ class JsonSchemaParser(Parser):
             # treat_something function
             ent.description = elt["description"]
 
-        self.model[name] = ent
+        if ent is not None:
+            self.model[name] = ent
         return ent, force_list
 
     def _treat_record_type(self, elt: dict, name: str):
@@ -795,6 +830,17 @@ class JsonSchemaParser(Parser):
                     rt.add_property(prop_ent, importance=importance,
                                     datatype=db.LIST(prop_ent))
 
+        if "patternProperties" in elt:
+
+            pattern_property_rts = self._treat_pattern_properties(
+                elt["patternProperties"], name_prefix=name)
+            for ppr in pattern_property_rts:
+                # add reference to pattern property type. These can never be
+                # obligatory since pattern properties cannot be required in the
+                # original schema (since their actual names are not known a
+                # priori).
+                rt.add_property(ppr)
+
         if "description" in elt:
             rt.description = elt["description"]
         return rt
@@ -818,26 +864,92 @@ class JsonSchemaParser(Parser):
     def _treat_list(self, elt: dict, name: str):
         # @review Timm Fitschen 2022-02-30
 
-        if "items" not in elt:
+        if "items" not in elt and name not in self.types_for_missing_array_items:
+            if self.ignore_unspecified_array_items:
+                return None, False
             raise JsonSchemaDefinitionError(
                 f"The definition of the list items is missing in {elt}.")
-        items = elt["items"]
-        if "enum" in items:
-            return self._treat_enum(items, name), True
-        if items["type"] in JSON_SCHEMA_ATOMIC_TYPES:
-            datatype = db.LIST(self._get_atomic_datatype(items))
+        if "items" in elt:
+            items = elt["items"]
+            if "enum" in items:
+                return self._treat_enum(items, name), True
+            if items["type"] in JSON_SCHEMA_ATOMIC_TYPES:
+                datatype = db.LIST(self._get_atomic_datatype(items))
+                return db.Property(name=name, datatype=datatype), False
+            if items["type"] == "object":
+                if "title" not in items or self._stringify(items["title"]) == name:
+                    # Property is RecordType
+                    return self._treat_record_type(items, name), True
+                else:
+                    # List property will be an entity of its own with a name
+                    # different from the referenced RT
+                    ref_rt = self._treat_record_type(
+                        items, self._stringify(items["title"]))
+                    self.model[ref_rt.name] = ref_rt
+                    return db.Property(name=name, datatype=db.LIST(ref_rt)), False
+        else:
+            # Use predefined type:
+            datatype = db.LIST(self.types_for_missing_array_items[name])
             return db.Property(name=name, datatype=datatype), False
-        if items["type"] == "object":
-            if "title" not in items or self._stringify(items["title"]) == name:
-                # Property is RecordType
-                return self._treat_record_type(items, name), True
+
+    def _get_pattern_prop(self):
+        if "__pattern_property_pattern_property" in self.model:
+            return self.model["__pattern_property_pattern_property"]
+        pp = db.Property(name="__matched_pattern", datatype=db.TEXT)
+        self.model["__pattern_property_pattern_property"] = pp
+        return pp
+
+    def _treat_pattern_properties(self, pattern_elements, name_prefix=""):
+        """Special Treatment for pattern properties: A RecordType is created for
+        each pattern property. In case of a `type: object` PatternProperty, the
+        remaining properties of the JSON entry are appended to the new
+        RecordType; in case of an atomic type PatternProperty, a single value
+        Property is added to the RecordType.
+
+        Raises
+        ------
+        NotImplementedError
+            In case of patternProperties with non-object, non-atomic type, e.g.,
+            array.
+
+        """
+        num_patterns = len(pattern_elements)
+        pattern_prop = self._get_pattern_prop()
+        returns = []
+        for ii, (key, element) in enumerate(pattern_elements.items()):
+            if not "title" in element:
+                name_suffix = f"_{ii+1}" if num_patterns > 1 else ""
+                name = name_prefix + "Entry" + name_suffix
+            else:
+                name = element["title"]
+            if element["type"] == "object":
+                # simple, is already an object, so can be treated like any other
+                # record type.
+                pattern_type = self._treat_record_type(element, name)
+            elif element["type"] in JSON_SCHEMA_ATOMIC_TYPES:
+                # create a property that stores the actual value of the pattern
+                # property.
+                propname = f"{name}_value"
+                prop = db.Property(name=propname, datatype=self._get_atomic_datatype(element))
+                self.model[propname] = prop
+                pattern_type = db.RecordType(name=name)
+                pattern_type.add_property(prop)
+            else:
+                raise NotImplementedError(
+                    "Pattern properties are currently only supported for types " +
+                    ", ".join(JSON_SCHEMA_ATOMIC_TYPES) + ", and object.")
+
+            # Add pattern property and description
+            pattern_type.add_property(pattern_prop, importance=db.OBLIGATORY)
+            if pattern_type.description:
+                pattern_type.description += f"\n\npattern: {key}"
             else:
-                # List property will be an entity of its own with a name
-                # different from the referenced RT
-                ref_rt = self._treat_record_type(
-                    items, self._stringify(items["title"]))
-                self.model[ref_rt.name] = ref_rt
-                return db.Property(name=name, datatype=db.LIST(ref_rt)), False
+                pattern_type.description = f"pattern: {key}"
+
+            self.model[name] = pattern_type
+            returns.append(pattern_type)
+
+        return returns
 
 
 if __name__ == "__main__":