add support for QuerySet.annotate() #39
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,6 +1,6 @@ | ||
| from django.core.exceptions import EmptyResultSet, FullResultSet | ||
| from django.db import DatabaseError, IntegrityError, NotSupportedError | ||
| from django.db.models import NOT_PROVIDED, Count, Expression | ||
| from django.db.models.aggregates import Aggregate | ||
| from django.db.models.constants import LOOKUP_SEP | ||
| from django.db.models.sql import compiler | ||
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@@ -22,8 +22,11 @@ def execute_sql( | |
| # QuerySet.count() | ||
| if self.query.annotations == {"__count": Count("*")}: | ||
| return [self.get_count()] | ||
| # Specify columns if there are any annotations so that annotations are | ||
| # computed via $project. | ||
| columns = self.get_columns() if self.query.annotations else None | ||
| try: | ||
| query = self.build_query(columns) | ||
| except EmptyResultSet: | ||
| return None | ||
| return query.fetch() | ||
|
|
@@ -55,13 +58,18 @@ def results_iter( | |
| def has_results(self): | ||
| return bool(self.get_count(check_exists=True)) | ||
|
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| def get_converters(self, expressions): | ||
| converters = {} | ||
| for name_expr in expressions: | ||
| try: | ||
| name, expr = name_expr | ||
| except TypeError: | ||
| # e.g., Count("*") | ||
| continue | ||
| backend_converters = self.connection.ops.get_db_converters(expr) | ||
| field_converters = expr.get_db_converters(self.connection) | ||
| if backend_converters or field_converters: | ||
| converters[name] = backend_converters + field_converters | ||
|
There was a problem hiding this comment. Django sql compiler uses an index. Like an integer and maintain the order. There was a problem hiding this comment. Right, however, MongoDB returns a document of (unordered?) fields, hence we may need to use the key lookup approach (or at least this was the reason for the original implementation in Django Mongo Engine + Python 2). Since Python 3.7 dictionaries are guaranteed to be insertion ordered. Not sure how the MongoDB server handles field ordering though (does it match the order of |
||
| return converters | ||
|
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||
| def _make_result(self, entity, columns, converters, tuple_expected=False): | ||
|
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@@ -72,15 +80,14 @@ def _make_result(self, entity, columns, converters, tuple_expected=False): | |
| names as keys. | ||
| """ | ||
| result = [] | ||
| for name, col in columns: | ||
| field = col.field | ||
| value = entity.get(name, NOT_PROVIDED) | ||
| if value is NOT_PROVIDED: | ||
| value = field.get_default() | ||
| elif converters: | ||
| # Decode values using Django's database converters API. | ||
| for converter in converters.get(name, ()): | ||
| value = converter(value, col, self.connection) | ||
| result.append(value) | ||
| if tuple_expected: | ||
|
|
@@ -91,12 +98,6 @@ def check_query(self): | |
| """Check if the current query is supported by the database.""" | ||
| if self.query.is_empty(): | ||
| raise EmptyResultSet() | ||
| if self.query.distinct: | ||
| # This is a heuristic to detect QuerySet.datetimes() and dates(). | ||
| # "datetimefield" and "datefield" are the names of the annotations | ||
|
|
@@ -144,11 +145,17 @@ def build_query(self, columns=None): | |
| return query | ||
|
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||
| def get_columns(self): | ||
| """ | ||
| Return a tuple of (name, expression) with the columns and annotations | ||
| which should be loaded by the query. | ||
| """ | ||
| select_mask = self.query.get_select_mask() | ||
| columns = ( | ||
| self.get_default_columns(select_mask) if self.query.default_cols else self.query.select | ||
| ) | ||
| return tuple((column.target.column, column) for column in columns) + tuple( | ||
| self.query.annotations.items() | ||
| ) | ||
|
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||
| def _get_ordering(self): | ||
| """ | ||
|
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||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,9 +1,19 @@ | ||
| from django.db.models.expressions import Col, Value | ||
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| def col(self, compiler, connection): # noqa: ARG001 | ||
| return f"${self.target.column}" | ||
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| def value(self, compiler, connection): # noqa: ARG001 | ||
| return self.value | ||
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| def value_agg(self, compiler, connection): # noqa: ARG001 | ||
| return {"$literal": self.value} | ||
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| def register_expressions(): | ||
| Col.as_mql = col | ||
| Value.as_mql = value | ||
| Value.as_mql_agg = value_agg |
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Can you elaborate on this? Why does SQL get generated if we're running a mongodb query?
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It has to do with how this library hooks in to the query generation process. See also:
https://github.com/mongodb-labs/django-mongodb/blob/3c3ad0eb45a2572453aa228ddafac96391dc1ab8/django_mongodb/query.py#L23-L32