Conditions | 3 |
Total Lines | 185 |
Lines | 0 |
Ratio | 0 % |
Changes | 11 | ||
Bugs | 0 | Features | 0 |
Small methods make your code easier to understand, in particular if combined with a good name. Besides, if your method is small, finding a good name is usually much easier.
For example, if you find yourself adding comments to a method's body, this is usually a good sign to extract the commented part to a new method, and use the comment as a starting point when coming up with a good name for this new method.
Commonly applied refactorings include:
If many parameters/temporary variables are present:
1 | # ~*~ coding: utf-8 ~*~ |
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21 | This class holds all the SQLAlchemy classes and logic that make up |
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22 | OSMAlchemy. It is contained in a separate class because it is a |
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23 | template that can be modified as needed by users, e.g. by using a |
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24 | different table prefix or a different declarative base. |
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25 | """ |
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26 | |||
27 | def __init__(self, base=None, prefix="osm_"): |
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28 | """ Initialise the table definitions in the wrapper object |
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29 | |||
30 | This function generates the OSM element classes as SQLAlchemy table |
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31 | declaratives. If called without an argument, it uses a newly created |
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32 | declarative base. |
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33 | |||
34 | The base argument, if provided, can be either a declarative base or |
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35 | a Flask-SQLAlchemy object. |
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36 | """ |
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37 | |||
38 | # Check what we got as declarative base |
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39 | if base is None: |
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40 | # Nothing, so create one |
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41 | base = declarative_base() |
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42 | elif hasattr(base, "Model"): |
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43 | # Unwrap Flask-SQLAlchemy object if we got one |
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44 | base = base.Model |
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45 | |||
46 | class OSMElement(base): |
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47 | """ Base class for all the conceptual OSM elements. """ |
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48 | |||
49 | # Name of the table in the database, prefix provided by user |
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50 | __tablename__ = prefix + "elements" |
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51 | |||
52 | # The internal ID of the element, only for structural use |
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53 | element_id = Column(Integer, primary_key=True) |
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54 | |||
55 | # Track element modification for OSMAlchemy caching |
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56 | osmalchemy_updated = Column(DateTime, default=datetime.datetime.now, |
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57 | onupdate=datetime.datetime.now) |
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58 | |||
59 | # The type of the element, used by SQLAlchemy for polymorphism |
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60 | type = Column(String(256)) |
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61 | |||
62 | # Tags belonging to the element |
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63 | # Accessed as a dictionary like {'name': 'value', 'name2': 'value2',…} |
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64 | # Uses proxying across several tables to OSMTag |
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65 | tags = association_proxy(prefix+"elements_tags", "tag_value", |
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66 | creator=lambda k, v: OSMElementsTags(tag_key=k, tag_value=v)) |
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67 | |||
68 | # Metadata shared by all element types |
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69 | version = Column(Integer) |
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70 | changeset = Column(Integer) |
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71 | user = Column(String) |
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72 | uid = Column(Integer) |
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73 | visible = Column(Bool) |
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74 | timestamp = Column(DateTime) |
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75 | |||
76 | # Configure polymorphism |
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77 | __mapper_args__ = { |
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78 | 'polymorphic_identity': prefix + 'elements', |
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79 | 'polymorphic_on': type, |
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80 | 'with_polymorphic': '*' |
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81 | } |
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82 | |||
83 | class OSMNode(OSMElement): |
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84 | """ An OSM node element. |
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85 | |||
86 | A node hast a latitude and longitude, which are non-optional, |
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87 | and a list of zero or more tags. |
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88 | """ |
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89 | |||
90 | # Name of the table in the database, prefix provided by user |
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91 | __tablename__ = prefix + "nodes" |
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92 | |||
93 | # The internal ID of the element, only for structural use |
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94 | # Synchronised with the id of the parent table OSMElement through polymorphism |
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95 | element_id = Column(Integer, ForeignKey(prefix + 'elements.element_id'), |
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96 | primary_key=True) |
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97 | |||
98 | # ID of the node, not to be confused with the primary key from OSMElements |
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99 | id = Column(Integer, unique=True) |
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100 | |||
101 | # Geographical coordinates of the node |
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102 | latitude = Column(Float, nullable=False) |
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103 | longitude = Column(Float, nullable=False) |
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104 | |||
105 | # Configure polymorphism with OSMElement |
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106 | __mapper_args__ = { |
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107 | 'polymorphic_identity': prefix + 'nodes', |
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108 | } |
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109 | |||
110 | def __init__(self, latitude=0.0, longitude=0.0, **kwargs): |
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111 | """ Initialisation with two main positional arguments. |
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112 | |||
113 | Shorthand for OSMNode(lat, lon). |
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114 | """ |
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115 | |||
116 | self.latitude = latitude |
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117 | self.longitude = longitude |
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118 | |||
119 | # Pass rest on to default constructor |
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120 | OSMElement.__init__(self, **kwargs) |
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121 | |||
122 | class OSMWaysNodes(base): |
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123 | """ Secondary mapping table for ways and nodes """ |
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124 | |||
125 | # Name of the table in the database, prefix provided by user |
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126 | __tablename__ = prefix + "ways_nodes" |
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127 | |||
128 | # Internal ID of the mapping, only for structural use |
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129 | map_id = Column(Integer, primary_key=True) |
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130 | |||
131 | # Foreign key columns for the connected way and node |
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132 | way_id = Column(Integer, ForeignKey(prefix + 'ways.element_id')) |
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133 | node_id = Column(Integer, ForeignKey(prefix + 'nodes.element_id')) |
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134 | # Relationships for proxy access |
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135 | way = relationship("OSMWay", foreign_keys=[way_id]) |
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136 | node = relationship("OSMNode", foreign_keys=[node_id]) |
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137 | |||
138 | # Index of the node in the way to maintain ordered list, structural use only |
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139 | position = Column(Integer) |
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140 | |||
141 | class OSMWay(OSMElement): |
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142 | """ An OSM way element (also area). |
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143 | |||
144 | Contains a list of two or more nodes and a list of zero or more |
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145 | tags. |
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146 | """ |
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147 | |||
148 | # Name of the table in the database, prefix provided by user |
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149 | __tablename__ = prefix + "ways" |
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150 | |||
151 | # The internal ID of the element, only for structural use |
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152 | # Synchronised with the id of the parent table OSMElement through polymorphism |
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153 | element_id = Column(Integer, ForeignKey(prefix + 'elements.element_id'), |
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154 | primary_key=True) |
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155 | |||
156 | # ID of the way, not to be confused with the primary key from OSMElements |
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157 | id = Column(Integer, unique=True) |
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158 | |||
159 | # Relationship with all nodes in the way |
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160 | # Uses association proxy and a collection class to maintain an ordered list, |
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161 | # synchronised with the position field of OSMWaysNodes |
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162 | _nodes = relationship('OSMWaysNodes', order_by="OSMWaysNodes.position", |
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163 | collection_class=ordering_list("position")) |
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164 | nodes = association_proxy("_nodes", "node", |
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165 | creator=lambda _n: OSMWaysNodes(node=_n)) |
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166 | |||
167 | # Configure polymorphism with OSMElement |
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168 | __mapper_args__ = { |
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169 | 'polymorphic_identity': prefix + 'ways', |
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170 | } |
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171 | |||
172 | class OSMElementsTags(base): |
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173 | """ Secondary mapping table for elements and tags """ |
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174 | |||
175 | # Name of the table in the database, prefix provided by user |
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176 | __tablename__ = prefix + "elements_tags" |
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177 | |||
178 | # Internal ID of the mapping, only for structural use |
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179 | map_id = Column(Integer, primary_key=True) |
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180 | |||
181 | # Foreign key columns for the element and tag of the mapping |
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182 | element_id = Column(Integer, ForeignKey(prefix + 'elements.element_id')) |
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183 | tag_id = Column(Integer, ForeignKey(prefix + 'tags.tag_id')) |
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184 | |||
185 | # Relationship with all the tags mapped to the element |
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186 | # The backref is the counter-part to the tags association proxy |
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187 | # in OSMElement to form the dictionary |
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188 | element = relationship("OSMElement", foreign_keys=[element_id], |
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189 | backref=backref(prefix+"elements_tags", |
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190 | collection_class=attribute_mapped_collection("tag_key"), |
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191 | cascade="all, delete-orphan")) |
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192 | |||
193 | # Relationship to the tag object and short-hand for its key and value |
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194 | # for use in the association proxy |
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195 | tag = relationship("OSMTag", foreign_keys=[tag_id]) |
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196 | tag_key = association_proxy("tag", "key") |
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197 | tag_value = association_proxy("tag", "value") |
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198 | |||
199 | class OSMRelationsElements(base): |
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200 | """ Secondary mapping table for relation members """ |
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201 | |||
202 | # Name of the table in the database, prefix provided by user |
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203 | __tablename__ = prefix + "relations_elements" |
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204 | |||
205 | # Internal ID of the mapping, only for structural use |
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206 | map_id = Column(Integer, primary_key=True) |
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296 |