| 1 | import sys |
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| 2 | from sqlalchemy import relation, ForeignKeyConstraint, Column, Table, \ |
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| 3 | backref, class_mapper, and_ |
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| 4 | from sqlalchemy.util import to_set |
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| 5 | from supermodel.statements import Statement |
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| 6 | from supermodel.fields import Field |
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| 7 | from supermodel.entity import EntityDescriptor |
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| 8 | |
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| 9 | |
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| 10 | class Relationship(object): |
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| 11 | """ |
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| 12 | Base class for relationships |
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| 13 | """ |
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| 14 | |
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| 15 | def __init__(self, entity, name, *args, **kwargs): |
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| 16 | self.name = name |
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| 17 | self.of_kind = kwargs.pop('of_kind') |
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| 18 | self.inverse_name = kwargs.pop('inverse', None) |
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| 19 | |
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| 20 | self.entity = entity |
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| 21 | self._target = None |
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| 22 | |
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| 23 | self.initialized = False |
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| 24 | self.secondary = None |
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| 25 | self._inverse = None |
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| 26 | self.foreign_key = None |
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| 27 | |
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| 28 | self.foreign_key = kwargs.pop('foreign_key', None) |
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| 29 | if self.foreign_key and not isinstance(self.foreign_key, list): |
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| 30 | self.foreign_key = [self.foreign_key] |
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| 31 | |
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| 32 | self.property = None # sqlalchemy property |
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| 33 | |
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| 34 | self.args = args |
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| 35 | self.kwargs = kwargs |
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| 36 | |
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| 37 | #CHECKME: is this useful? |
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| 38 | self.entity._descriptor.relationships[self.name] = self |
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| 39 | |
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| 40 | def create_keys(self): |
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| 41 | """ |
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| 42 | Subclasses (ie. concrete relationships) may |
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| 43 | override this method to create foreign keys |
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| 44 | """ |
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| 45 | pass |
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| 46 | |
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| 47 | def create_tables(self): |
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| 48 | """ |
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| 49 | Subclasses (ie. concrete relationships) may |
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| 50 | override this method to create secondary tables |
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| 51 | """ |
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| 52 | pass |
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| 53 | |
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| 54 | def create_properties(self): |
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| 55 | """ |
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| 56 | Subclasses (ie. concrete relationships) may |
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| 57 | override this method to add properties to the |
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| 58 | involved entities |
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| 59 | """ |
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| 60 | pass |
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| 61 | |
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| 62 | def setup(self): |
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| 63 | """ |
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| 64 | Sets up the relationship, creates foreign keys |
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| 65 | and secondary tables |
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| 66 | """ |
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| 67 | |
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| 68 | if not self.target: |
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| 69 | return False |
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| 70 | |
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| 71 | self.create_keys() |
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| 72 | self.create_tables() |
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| 73 | self.create_properties() |
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| 74 | |
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| 75 | return True |
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| 76 | |
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| 77 | @property |
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| 78 | def target(self): |
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| 79 | if not self._target: |
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| 80 | path = self.of_kind.rsplit('.', 1) |
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| 81 | classname = path.pop() |
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| 82 | |
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| 83 | # full qualified entity name? |
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| 84 | if path: |
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| 85 | module = sys.modules[path.pop()] |
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| 86 | # if not, try the same module as the source |
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| 87 | else: |
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| 88 | module = self.entity._descriptor.module |
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| 89 | |
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| 90 | try: |
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| 91 | self._target = getattr(module, classname) |
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| 92 | except AttributeError: |
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| 93 | # This is ugly but we need it because the class which is |
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| 94 | # currently being defined (we have to keep in mind we are in |
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| 95 | # its metaclass code) is not yet available in the module |
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| 96 | # namespace, so the getattr above fails. And unfortunately, |
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| 97 | # this doesn't only happen for the owning entity of this |
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| 98 | # relation since we might be setting up a deferred relation. |
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| 99 | e = EntityDescriptor.current.entity |
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| 100 | if classname == e.__name__ or \ |
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| 101 | self.of_kind == e.__module__ +'.'+ e.__name__: |
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| 102 | self._target = e |
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| 103 | else: |
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| 104 | return None |
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| 105 | |
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| 106 | return self._target |
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| 107 | |
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| 108 | @property |
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| 109 | def inverse(self): |
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| 110 | #TODO: we should use a different value for when an inverse was searched |
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| 111 | # for but none was found than when it hasn't been searched for yet so |
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| 112 | # that we don't do the whole search again |
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| 113 | if not self._inverse: |
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| 114 | if self.inverse_name: |
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| 115 | desc = self.target._descriptor |
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| 116 | inverse = desc.relationships[self.inverse_name] |
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| 117 | assert self.match_type_of(inverse) |
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| 118 | else: |
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| 119 | inverse = self.target._descriptor.get_inverse_relation(self) |
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| 120 | |
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| 121 | if inverse: |
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| 122 | self._inverse = inverse |
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| 123 | inverse._inverse = self |
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| 124 | |
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| 125 | return self._inverse |
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| 126 | |
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| 127 | def match_type_of(self, other): |
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| 128 | t1, t2 = type(self), type(other) |
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| 129 | |
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| 130 | if t1 is HasAndBelongsToMany: |
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| 131 | return t1 is t2 |
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| 132 | elif t1 in (HasOne, HasMany): |
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| 133 | return t2 is BelongsTo |
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| 134 | elif t1 is BelongsTo: |
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| 135 | return t2 in (HasMany, HasOne) |
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| 136 | else: |
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| 137 | return False |
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| 138 | |
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| 139 | def is_inverse(self, other): |
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| 140 | return other is not self and \ |
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| 141 | self.match_type_of(other) and \ |
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| 142 | self.entity == other.target and \ |
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| 143 | other.entity == self.target and \ |
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| 144 | (self.inverse_name == other.name or not self.inverse_name) and \ |
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| 145 | (other.inverse_name == self.name or not other.inverse_name) |
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| 146 | |
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| 147 | class BelongsTo(Relationship): |
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| 148 | def create_keys(self): |
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| 149 | """ |
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| 150 | Find all primary keys on the target and create |
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| 151 | foreign keys on the source accordingly |
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| 152 | """ |
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| 153 | source_desc = self.entity._descriptor |
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| 154 | target_desc = self.target._descriptor |
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| 155 | |
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| 156 | if self.foreign_key: |
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| 157 | self.foreign_key = [source_desc.fields[k] |
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| 158 | for k in self.foreign_key |
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| 159 | if isinstance(k, basestring)] |
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| 160 | return |
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| 161 | |
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| 162 | fk_refcols = list() |
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| 163 | fk_colnames = list() |
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| 164 | |
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| 165 | self.foreign_key = list() |
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| 166 | self.primaryjoin_clauses = list() |
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| 167 | |
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| 168 | for key in target_desc.primary_keys: |
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| 169 | pk_col = key.column |
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| 170 | |
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| 171 | colname = '%s_%s' % (self.name, pk_col.name) |
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| 172 | # we use a Field here instead of using a Column directly |
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| 173 | # because of add_field |
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| 174 | field = Field(pk_col.type, colname=colname, index=True) |
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| 175 | source_desc.add_field(field) |
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| 176 | |
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| 177 | self.foreign_key.append(field) |
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| 178 | |
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| 179 | # build the list of local columns which will be part of |
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| 180 | # the foreign key |
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| 181 | fk_colnames.append(colname) |
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| 182 | |
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| 183 | # build the list of columns the foreign key will point to |
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| 184 | fk_refcols.append(target_desc.tablename + '.' + pk_col.name) |
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| 185 | |
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| 186 | # build up the primary join. This is needed when you have several |
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| 187 | # belongs_to relations between two objects |
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| 188 | self.primaryjoin_clauses.append(field.column == pk_col) |
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| 189 | |
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| 190 | # TODO: better constraint-naming? |
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| 191 | #CHECKME: do we really need use_alter systematically? |
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| 192 | source_desc.add_constraint(ForeignKeyConstraint( |
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| 193 | fk_colnames, fk_refcols, |
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| 194 | name=self.name +'_fk', |
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| 195 | use_alter=True)) |
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| 196 | |
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| 197 | def create_properties(self): |
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| 198 | kwargs = self.kwargs |
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| 199 | |
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| 200 | if self.entity is self.target: |
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| 201 | cols = [k.column for k in self.target._descriptor.primary_keys] |
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| 202 | kwargs['remote_side'] = cols |
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| 203 | |
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| 204 | kwargs['primaryjoin'] = and_(*self.primaryjoin_clauses) |
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| 205 | kwargs['uselist'] = False |
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| 206 | |
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| 207 | self.property = relation(self.target, **kwargs) |
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| 208 | self.entity.mapper.add_property(self.name, self.property) |
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| 209 | |
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| 210 | |
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| 211 | class HasOne(Relationship): |
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| 212 | uselist = False |
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| 213 | |
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| 214 | def create_keys(self): |
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| 215 | # make sure the inverse is set up because it creates the |
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| 216 | # foreign key we'll need |
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| 217 | self.inverse.setup() |
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| 218 | |
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| 219 | def create_properties(self): |
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| 220 | kwargs = self.kwargs |
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| 221 | |
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| 222 | if self.entity is self.target: |
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| 223 | kwargs['remote_side'] = [field.column |
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| 224 | for field in self.inverse.foreign_key] |
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| 225 | |
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| 226 | kwargs['primaryjoin'] = and_(*self.inverse.primaryjoin_clauses) |
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| 227 | kwargs['uselist'] = self.uselist |
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| 228 | |
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| 229 | self.property = relation(self.target, **kwargs) |
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| 230 | self.entity.mapper.add_property(self.name, self.property) |
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| 231 | |
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| 232 | |
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| 233 | class HasMany(HasOne): |
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| 234 | uselist = True |
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| 235 | |
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| 236 | |
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| 237 | class HasAndBelongsToMany(Relationship): |
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| 238 | def create_tables(self): |
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| 239 | if self.inverse: |
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| 240 | if self.inverse.secondary: |
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| 241 | self.secondary = self.inverse.secondary |
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| 242 | self.primaryjoin_clauses = self.inverse.secondaryjoin_clauses |
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| 243 | self.secondaryjoin_clauses = self.inverse.primaryjoin_clauses |
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| 244 | |
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| 245 | if not self.secondary: |
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| 246 | e1_desc = self.entity._descriptor |
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| 247 | e2_desc = self.target._descriptor |
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| 248 | |
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| 249 | columns = list() |
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| 250 | constraints = list() |
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| 251 | |
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| 252 | self.primaryjoin_clauses = list() |
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| 253 | self.secondaryjoin_clauses = list() |
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| 254 | |
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| 255 | for num, desc, join_name in (('1', e1_desc, 'primary'), |
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| 256 | ('2', e2_desc, 'secondary')): |
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| 257 | fk_colnames = list() |
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| 258 | fk_refcols = list() |
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| 259 | |
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| 260 | for key in desc.primary_keys: |
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| 261 | pk_col = key.column |
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| 262 | |
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| 263 | colname = '%s_%s' % (desc.tablename, pk_col.name) |
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| 264 | |
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| 265 | # In case we have a many-to-many self-reference, we need |
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| 266 | # to tweak the names of the columns so that we don't end |
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| 267 | # up with twice the same column name. |
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| 268 | if self.entity is self.target: |
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| 269 | colname += num |
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| 270 | |
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| 271 | col = Column(colname, pk_col.type) |
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| 272 | columns.append(col) |
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| 273 | |
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| 274 | # build the list of local columns which will be part of |
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| 275 | # the foreign key |
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| 276 | fk_colnames.append(colname) |
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| 277 | |
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| 278 | # build the list of columns the foreign key will point to |
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| 279 | fk_refcols.append(desc.tablename + '.' + pk_col.name) |
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| 280 | |
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| 281 | # build join clauses |
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| 282 | join_list = getattr(self, join_name+'join_clauses') |
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| 283 | join_list.append(col == pk_col) |
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| 284 | |
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| 285 | # TODO: better constraint-naming? |
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| 286 | #CHECKME: do we really need use_alter systematically? |
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| 287 | constraints.append( |
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| 288 | ForeignKeyConstraint(fk_colnames, fk_refcols, |
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| 289 | name=desc.tablename + '_fk', |
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| 290 | use_alter=True)) |
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| 291 | |
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| 292 | # In the table name code below, we use the name of the relation |
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| 293 | # for the first entity (instead of the name of its primary key), |
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| 294 | # so that we can have two many-to-many relations between the same |
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| 295 | # objects without having a table name collision. On the other hand, |
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| 296 | # we use the name of the primary key for the second entity |
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| 297 | # (instead of the inverse relation's name) so that a many-to-many |
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| 298 | # relation can be defined without inverse. |
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| 299 | e2_pk_name = '_'.join([key.column.name for key in |
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| 300 | e2_desc.primary_keys]) |
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| 301 | tablename = "%s_%s__%s_%s" % (e1_desc.tablename, self.name, |
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| 302 | e2_desc.tablename, e2_pk_name) |
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| 303 | |
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| 304 | args = columns + constraints |
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| 305 | self.secondary = Table(tablename, e1_desc.metadata, *args) |
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| 306 | |
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| 307 | def create_properties(self): |
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| 308 | kwargs = self.kwargs |
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| 309 | |
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| 310 | if self.target is self.entity: |
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| 311 | kwargs['primaryjoin'] = and_(*self.primaryjoin_clauses) |
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| 312 | kwargs['secondaryjoin'] = and_(*self.secondaryjoin_clauses) |
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| 313 | |
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| 314 | m = self.entity.mapper |
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| 315 | #FIXME: using post_update systematically is *really* not good |
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| 316 | m.add_property(self.name, |
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| 317 | relation(self.target, secondary=self.secondary, |
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| 318 | uselist=True, **kwargs)) |
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| 319 | |
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| 320 | |
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| 321 | belongs_to = Statement(BelongsTo) |
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| 322 | has_one = Statement(HasOne) |
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| 323 | has_many = Statement(HasMany) |
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| 324 | has_and_belongs_to_many = Statement(HasAndBelongsToMany) |
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