|
| 1 | +import difflib |
| 2 | + |
| 3 | +from django.core.exceptions import FieldDoesNotExist |
| 4 | +from django.db.models import Field, lookups |
| 5 | +from django.db.models.expressions import Col |
| 6 | +from django.db.models.lookups import Lookup, Transform |
| 7 | + |
| 8 | +from .. import forms |
| 9 | +from ..query_utils import process_lhs, process_rhs |
| 10 | +from . import EmbeddedModelField |
| 11 | +from .array import ArrayField |
| 12 | + |
| 13 | + |
| 14 | +class EmbeddedModelArrayField(ArrayField): |
| 15 | + ALLOWED_LOOKUPS = {"exact", "len", "overlap"} |
| 16 | + |
| 17 | + def __init__(self, embedded_model, **kwargs): |
| 18 | + if "size" in kwargs: |
| 19 | + raise ValueError("EmbeddedModelArrayField does not support size.") |
| 20 | + super().__init__(EmbeddedModelField(embedded_model), **kwargs) |
| 21 | + self.embedded_model = embedded_model |
| 22 | + |
| 23 | + def deconstruct(self): |
| 24 | + name, path, args, kwargs = super().deconstruct() |
| 25 | + if path == "django_mongodb_backend.fields.embedded_model_array.EmbeddedModelArrayField": |
| 26 | + path = "django_mongodb_backend.fields.EmbeddedModelArrayField" |
| 27 | + kwargs["embedded_model"] = self.embedded_model |
| 28 | + del kwargs["base_field"] |
| 29 | + return name, path, args, kwargs |
| 30 | + |
| 31 | + def get_db_prep_value(self, value, connection, prepared=False): |
| 32 | + if isinstance(value, list | tuple): |
| 33 | + # Must call get_db_prep_save() rather than get_db_prep_value() |
| 34 | + # to transform model instances to dicts. |
| 35 | + return [self.base_field.get_db_prep_save(i, connection) for i in value] |
| 36 | + if value is not None: |
| 37 | + raise TypeError( |
| 38 | + f"Expected list of {self.embedded_model!r} instances, not {type(value)!r}." |
| 39 | + ) |
| 40 | + return value |
| 41 | + |
| 42 | + def formfield(self, **kwargs): |
| 43 | + # Skip ArrayField.formfield() which has some differeences, including |
| 44 | + # unneeded "base_field" and "max_length" instead of "max_num". |
| 45 | + return Field.formfield( |
| 46 | + self, |
| 47 | + **{ |
| 48 | + "form_class": forms.EmbeddedModelArrayField, |
| 49 | + "model": self.base_field.embedded_model, |
| 50 | + "max_num": self.max_size, |
| 51 | + "prefix": self.name, |
| 52 | + **kwargs, |
| 53 | + }, |
| 54 | + ) |
| 55 | + |
| 56 | + def get_transform(self, name): |
| 57 | + transform = super().get_transform(name) |
| 58 | + if transform: |
| 59 | + return transform |
| 60 | + return KeyTransformFactory(name, self) |
| 61 | + |
| 62 | + def get_lookup(self, name): |
| 63 | + return super().get_lookup(name) if name in self.ALLOWED_LOOKUPS else None |
| 64 | + |
| 65 | + |
| 66 | +class EMFArrayRHSMixin: |
| 67 | + def check_lhs(self): |
| 68 | + if not isinstance(self.lhs, KeyTransform): |
| 69 | + raise ValueError( |
| 70 | + "Cannot apply this lookup directly to EmbeddedModelArrayField. " |
| 71 | + "Try querying one of its embedded fields instead." |
| 72 | + ) |
| 73 | + |
| 74 | + def process_rhs(self, compiler, connection): |
| 75 | + values = self.rhs |
| 76 | + # Value must be serealized based on the query target. |
| 77 | + # If querying a subfield inside the array (i.e., a nested KeyTransform), use the output |
| 78 | + # field of the subfield. Otherwise, use the base field of the array itself. |
| 79 | + get_db_prep_value = self.lhs._lhs.output_field.get_db_prep_value |
| 80 | + return None, [get_db_prep_value(values, connection, prepared=True)] |
| 81 | + |
| 82 | + |
| 83 | +@EmbeddedModelArrayField.register_lookup |
| 84 | +class EMFArrayExact(EMFArrayRHSMixin, lookups.Exact): |
| 85 | + def as_mql(self, compiler, connection): |
| 86 | + self.check_lhs() |
| 87 | + lhs_mql, inner_lhs_mql = process_lhs(self, compiler, connection) |
| 88 | + value = process_rhs(self, compiler, connection) |
| 89 | + return { |
| 90 | + "$anyElementTrue": { |
| 91 | + "$ifNull": [ |
| 92 | + { |
| 93 | + "$map": { |
| 94 | + "input": lhs_mql, |
| 95 | + "as": "item", |
| 96 | + "in": {"$eq": [inner_lhs_mql, value]}, |
| 97 | + } |
| 98 | + }, |
| 99 | + [], |
| 100 | + ] |
| 101 | + } |
| 102 | + } |
| 103 | + |
| 104 | + |
| 105 | +@EmbeddedModelArrayField.register_lookup |
| 106 | +class ArrayOverlap(EMFArrayRHSMixin, Lookup): |
| 107 | + lookup_name = "overlap" |
| 108 | + |
| 109 | + def as_mql(self, compiler, connection): |
| 110 | + self.check_lhs() |
| 111 | + # Querying a subfield within the array elements (via nested KeyTransform). |
| 112 | + # Replicates MongoDB's implicit ANY-match by mapping over the array and applying |
| 113 | + # `$in` on the subfield. |
| 114 | + lhs_mql = process_lhs(self, compiler, connection) |
| 115 | + values = process_rhs(self, compiler, connection) |
| 116 | + lhs_mql, inner_lhs_mql = lhs_mql |
| 117 | + return { |
| 118 | + "$anyElementTrue": { |
| 119 | + "$ifNull": [ |
| 120 | + { |
| 121 | + "$map": { |
| 122 | + "input": lhs_mql, |
| 123 | + "as": "item", |
| 124 | + "in": {"$in": [inner_lhs_mql, values]}, |
| 125 | + } |
| 126 | + }, |
| 127 | + [], |
| 128 | + ] |
| 129 | + } |
| 130 | + } |
| 131 | + |
| 132 | + |
| 133 | +class KeyTransform(Transform): |
| 134 | + def __init__(self, key_name, array_field, *args, **kwargs): |
| 135 | + super().__init__(*args, **kwargs) |
| 136 | + self.array_field = array_field |
| 137 | + self.key_name = key_name |
| 138 | + # The iteration items begins from the base_field, a virtual column with |
| 139 | + # base field output type is created. |
| 140 | + column_target = array_field.embedded_model._meta.get_field(key_name).clone() |
| 141 | + column_name = f"$item.{key_name}" |
| 142 | + column_target.db_column = column_name |
| 143 | + column_target.set_attributes_from_name(column_name) |
| 144 | + self._lhs = Col(None, column_target) |
| 145 | + self._sub_transform = None |
| 146 | + |
| 147 | + def __call__(self, this, *args, **kwargs): |
| 148 | + self._lhs = self._sub_transform(self._lhs, *args, **kwargs) |
| 149 | + return self |
| 150 | + |
| 151 | + def get_lookup(self, name): |
| 152 | + return self.output_field.get_lookup(name) |
| 153 | + |
| 154 | + def get_transform(self, name): |
| 155 | + """ |
| 156 | + Validate that `name` is either a field of an embedded model or a |
| 157 | + lookup on an embedded model's field. |
| 158 | + """ |
| 159 | + # Once the sub lhs is a transform, all the filter are applied over it. |
| 160 | + # Otherwise get transform from EMF. |
| 161 | + if transform := self._lhs.get_transform(name): |
| 162 | + self._sub_transform = transform |
| 163 | + return self |
| 164 | + output_field = self._lhs.output_field |
| 165 | + suggested_lookups = difflib.get_close_matches(name, output_field.get_lookups()) |
| 166 | + if suggested_lookups: |
| 167 | + suggested_lookups = " or ".join(suggested_lookups) |
| 168 | + suggestion = f", perhaps you meant {suggested_lookups}?" |
| 169 | + else: |
| 170 | + suggestion = "" |
| 171 | + raise FieldDoesNotExist( |
| 172 | + f"Unsupported lookup '{name}' for " |
| 173 | + f"EmbeddedModelArrayField of '{output_field.__class__.__name__}'" |
| 174 | + f"{suggestion}" |
| 175 | + ) |
| 176 | + |
| 177 | + def as_mql(self, compiler, connection): |
| 178 | + inner_lhs_mql = self._lhs.as_mql(compiler, connection) |
| 179 | + lhs_mql = process_lhs(self, compiler, connection) |
| 180 | + return lhs_mql, inner_lhs_mql |
| 181 | + |
| 182 | + @property |
| 183 | + def output_field(self): |
| 184 | + return self.array_field |
| 185 | + |
| 186 | + |
| 187 | +class KeyTransformFactory: |
| 188 | + def __init__(self, key_name, base_field): |
| 189 | + self.key_name = key_name |
| 190 | + self.base_field = base_field |
| 191 | + |
| 192 | + def __call__(self, *args, **kwargs): |
| 193 | + return KeyTransform(self.key_name, self.base_field, *args, **kwargs) |
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