Coverage for python/lsst/daf/butler/core/dimensions/_schema.py: 22%
97 statements
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1# This file is part of daf_butler.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (http://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <http://www.gnu.org/licenses/>.
21from __future__ import annotations
23__all__ = ("addDimensionForeignKey",)
25import copy
26from typing import TYPE_CHECKING, Tuple
28from .. import ddl
29from ..named import NamedValueSet
30from ..timespan import TimespanDatabaseRepresentation
32if TYPE_CHECKING: # Imports needed only for type annotations; may be circular. 32 ↛ 33line 32 didn't jump to line 33, because the condition on line 32 was never true
33 from ._elements import Dimension, DimensionElement
36def _makeForeignKeySpec(dimension: Dimension) -> ddl.ForeignKeySpec:
37 """Make a `ddl.ForeignKeySpec`.
39 This will reference the table for the given `Dimension` table.
41 Most callers should use the higher-level `addDimensionForeignKey` function
42 instead.
44 Parameters
45 ----------
46 dimension : `Dimension`
47 The dimension to be referenced. Caller guarantees that it is actually
48 associated with a table.
50 Returns
51 -------
52 spec : `ddl.ForeignKeySpec`
53 A database-agnostic foreign key specification.
54 """
55 source = []
56 target = []
57 for other in dimension.required:
58 if other == dimension:
59 target.append(dimension.primaryKey.name)
60 else:
61 target.append(other.name)
62 source.append(other.name)
63 return ddl.ForeignKeySpec(table=dimension.name, source=tuple(source), target=tuple(target))
66def addDimensionForeignKey(
67 tableSpec: ddl.TableSpec,
68 dimension: Dimension,
69 *,
70 primaryKey: bool,
71 nullable: bool = False,
72 constraint: bool = True,
73) -> ddl.FieldSpec:
74 """Add a field and possibly a foreign key to a table specification.
76 The field will reference the table for the given `Dimension`.
78 Parameters
79 ----------
80 tableSpec : `ddl.TableSpec`
81 Specification the field and foreign key are to be added to.
82 dimension : `Dimension`
83 Dimension to be referenced. If this dimension has required
84 dependencies, those must have already been added to the table. A field
85 will be added that correspond to this dimension's primary key, and a
86 foreign key constraint will be added only if the dimension is
87 associated with a table of its own.
88 primaryKey : `bool`
89 If `True`, the new field will be added as part of a compound primary
90 key for the table.
91 nullable : `bool`, optional
92 If `False` (default) the new field will be added with a NOT NULL
93 constraint.
94 constraint : `bool`
95 If `False` (`True` is default), just add the field, not the foreign
96 key constraint.
98 Returns
99 -------
100 fieldSpec : `ddl.FieldSpec`
101 Specification for the field just added.
102 """
103 # Add the dependency's primary key field, but use the dimension name for
104 # the field name to make it unique and more meaningful in this table.
105 fieldSpec = copy.copy(dimension.primaryKey)
106 fieldSpec.name = dimension.name
107 fieldSpec.primaryKey = primaryKey
108 fieldSpec.nullable = nullable
109 tableSpec.fields.add(fieldSpec)
110 # Also add a foreign key constraint on the dependency table, but only if
111 # there actually is one and we weren't told not to.
112 if dimension.hasTable() and dimension.viewOf is None and constraint:
113 tableSpec.foreignKeys.append(_makeForeignKeySpec(dimension))
114 return fieldSpec
117class DimensionElementFields:
118 """Class for constructing table schemas for `DimensionElement`.
120 This creates an object that constructs the table schema for a
121 `DimensionElement` and provides a categorized view of its fields.
123 Parameters
124 ----------
125 element : `DimensionElement`
126 Element for which to make a table specification.
128 Notes
129 -----
130 This combines the foreign key fields from dependencies, unique keys
131 for true `Dimension` instances, metadata fields, and region/timestamp
132 fields for spatial/temporal elements.
134 Callers should use `DimensionUniverse.makeSchemaSpec` if they want to
135 account for elements that have no table or reference another table; this
136 class simply creates a specification for the table an element _would_ have
137 without checking whether it does have one. That can be useful in contexts
138 (e.g. `DimensionRecord`) where we want to simulate the existence of such a
139 table.
140 """
142 def __init__(self, element: DimensionElement):
143 self.element = element
144 self._tableSpec = ddl.TableSpec(fields=())
145 # Add the primary key fields of required dimensions. These continue to
146 # be primary keys in the table for this dimension.
147 self.required = NamedValueSet()
148 self.dimensions = NamedValueSet()
149 self.facts = NamedValueSet()
150 self.standard = NamedValueSet()
151 dependencies = []
152 for dimension in element.required:
153 if dimension != element:
154 fieldSpec = addDimensionForeignKey(self._tableSpec, dimension, primaryKey=True)
155 dependencies.append(fieldSpec.name)
156 else:
157 fieldSpec = element.primaryKey # type: ignore
158 # A Dimension instance is in its own required dependency graph
159 # (always at the end, because of topological ordering). In
160 # this case we don't want to rename the field.
161 self._tableSpec.fields.add(fieldSpec)
162 self.required.add(fieldSpec)
163 self.dimensions.add(fieldSpec)
164 self.standard.add(fieldSpec)
165 # Add fields and foreign keys for implied dimensions. These are
166 # primary keys in their own table, but should not be here. As with
167 # required dependencies, we rename the fields with the dimension name.
168 # We use element.implied instead of element.graph.implied because we
169 # don't want *recursive* implied dependencies.
170 self.implied = NamedValueSet()
171 for dimension in element.implied:
172 fieldSpec = addDimensionForeignKey(self._tableSpec, dimension, primaryKey=False, nullable=False)
173 self.implied.add(fieldSpec)
174 self.dimensions.add(fieldSpec)
175 self.standard.add(fieldSpec)
176 # Add non-primary unique keys and unique constraints for them.
177 for fieldSpec in getattr(element, "alternateKeys", ()):
178 self._tableSpec.fields.add(fieldSpec)
179 self._tableSpec.unique.add(tuple(dependencies) + (fieldSpec.name,))
180 self.standard.add(fieldSpec)
181 self.facts.add(fieldSpec)
182 # Add other metadata fields.
183 for fieldSpec in element.metadata:
184 self._tableSpec.fields.add(fieldSpec)
185 self.standard.add(fieldSpec)
186 self.facts.add(fieldSpec)
187 names = list(self.standard.names)
188 # Add fields for regions and/or timespans.
189 if element.spatial is not None:
190 names.append("region")
191 if element.temporal is not None:
192 names.append(TimespanDatabaseRepresentation.NAME)
193 self.names = tuple(names)
195 def makeTableSpec(
196 self,
197 TimespanReprClass: type[TimespanDatabaseRepresentation],
198 ) -> ddl.TableSpec:
199 """Construct a complete specification for a table.
201 The table could hold the records of this element.
203 Parameters
204 ----------
205 TimespanReprClass : `type` [ `TimespanDatabaseRepresentation` ]
206 Class object that specifies how timespans are represented in the
207 database.
209 Returns
210 -------
211 spec : `ddl.TableSpec`
212 Specification for a table.
213 """
214 if self.element.temporal is not None or self.element.spatial is not None:
215 spec = ddl.TableSpec(
216 fields=NamedValueSet(self._tableSpec.fields),
217 unique=self._tableSpec.unique,
218 indexes=self._tableSpec.indexes,
219 foreignKeys=self._tableSpec.foreignKeys,
220 )
221 if self.element.spatial is not None:
222 spec.fields.add(ddl.FieldSpec.for_region())
223 if self.element.temporal is not None:
224 spec.fields.update(TimespanReprClass.makeFieldSpecs(nullable=True))
225 else:
226 spec = self._tableSpec
227 return spec
229 def __str__(self) -> str:
230 lines = [f"{self.element.name}: "]
231 lines.extend(f" {field.name}: {field.getPythonType().__name__}" for field in self.standard)
232 if self.element.spatial is not None:
233 lines.append(" region: lsst.sphgeom.Region")
234 if self.element.temporal is not None:
235 lines.append(" timespan: lsst.daf.butler.Timespan")
236 return "\n".join(lines)
238 element: DimensionElement
239 """The dimension element these fields correspond to.
241 (`DimensionElement`)
242 """
244 required: NamedValueSet[ddl.FieldSpec]
245 """The required dimension fields of this table.
247 They correspond to the element's required
248 dimensions, in that order, i.e. `DimensionElement.required`
249 (`NamedValueSet` [ `ddl.FieldSpec` ]).
250 """
252 implied: NamedValueSet[ddl.FieldSpec]
253 """The implied dimension fields of this table.
255 They correspond to the element's implied
256 dimensions, in that order, i.e. `DimensionElement.implied`
257 (`NamedValueSet` [ `ddl.FieldSpec` ]).
258 """
260 dimensions: NamedValueSet[ddl.FieldSpec]
261 """The direct and implied dimension fields of this table.
263 They correspond to the element's direct
264 required and implied dimensions, in that order, i.e.
265 `DimensionElement.dimensions` (`NamedValueSet` [ `ddl.FieldSpec` ]).
266 """
268 facts: NamedValueSet[ddl.FieldSpec]
269 """The standard fields of this table that do not correspond to dimensions.
271 (`NamedValueSet` [ `ddl.FieldSpec` ]).
273 This is equivalent to ``standard - dimensions`` (but possibly in a
274 different order).
275 """
277 standard: NamedValueSet[ddl.FieldSpec]
278 """All standard fields that are expected to have the same form.
280 They are expected to have the same form in all
281 databases; this is all fields other than those that represent a region
282 and/or timespan (`NamedValueSet` [ `ddl.FieldSpec` ]).
283 """
285 names: Tuple[str, ...]
286 """The names of all fields in the specification (`tuple` [ `str` ]).
288 This includes "region" and/or "timespan" if `element` is spatial and/or
289 temporal (respectively). The actual database representation of these
290 quantities may involve multiple fields (or even fields only on a different
291 table), but the Python representation of those rows (i.e. `DimensionRecord`
292 instances) will always contain exactly these fields.
293 """