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from ..helpers import quote_string, random_string, stringify_param_value
from .commands import GraphCommands
from .edge import Edge # noqa
from .node import Node # noqa
from .path import Path # noqa
class Graph(GraphCommands):
"""
Graph, collection of nodes and edges.
"""
def __init__(self, client, name=random_string()):
"""
Create a new graph.
"""
self.NAME = name # Graph key
self.client = client
self.execute_command = client.execute_command
self.nodes = {}
self.edges = []
self._labels = [] # List of node labels.
self._properties = [] # List of properties.
self._relationshipTypes = [] # List of relation types.
self.version = 0 # Graph version
@property
def name(self):
return self.NAME
def _clear_schema(self):
self._labels = []
self._properties = []
self._relationshipTypes = []
def _refresh_schema(self):
self._clear_schema()
self._refresh_labels()
self._refresh_relations()
self._refresh_attributes()
def _refresh_labels(self):
lbls = self.labels()
# Unpack data.
self._labels = [None] * len(lbls)
for i, l in enumerate(lbls):
self._labels[i] = l[0]
def _refresh_relations(self):
rels = self.relationshipTypes()
# Unpack data.
self._relationshipTypes = [None] * len(rels)
for i, r in enumerate(rels):
self._relationshipTypes[i] = r[0]
def _refresh_attributes(self):
props = self.propertyKeys()
# Unpack data.
self._properties = [None] * len(props)
for i, p in enumerate(props):
self._properties[i] = p[0]
def get_label(self, idx):
"""
Returns a label by it's index
Args:
idx:
The index of the label
"""
try:
label = self._labels[idx]
except IndexError:
# Refresh labels.
self._refresh_labels()
label = self._labels[idx]
return label
def get_relation(self, idx):
"""
Returns a relationship type by it's index
Args:
idx:
The index of the relation
"""
try:
relationship_type = self._relationshipTypes[idx]
except IndexError:
# Refresh relationship types.
self._refresh_relations()
relationship_type = self._relationshipTypes[idx]
return relationship_type
def get_property(self, idx):
"""
Returns a property by it's index
Args:
idx:
The index of the property
"""
try:
propertie = self._properties[idx]
except IndexError:
# Refresh properties.
self._refresh_attributes()
propertie = self._properties[idx]
return propertie
def add_node(self, node):
"""
Adds a node to the graph.
"""
if node.alias is None:
node.alias = random_string()
self.nodes[node.alias] = node
def add_edge(self, edge):
"""
Adds an edge to the graph.
"""
if not (self.nodes[edge.src_node.alias] and self.nodes[edge.dest_node.alias]):
raise AssertionError("Both edge's end must be in the graph")
self.edges.append(edge)
def _build_params_header(self, params):
if not isinstance(params, dict):
raise TypeError("'params' must be a dict")
# Header starts with "CYPHER"
params_header = "CYPHER "
for key, value in params.items():
params_header += str(key) + "=" + stringify_param_value(value) + " "
return params_header
# Procedures.
def call_procedure(self, procedure, *args, read_only=False, **kwagrs):
args = [quote_string(arg) for arg in args]
q = f"CALL {procedure}({','.join(args)})"
y = kwagrs.get("y", None)
if y:
q += f" YIELD {','.join(y)}"
return self.query(q, read_only=read_only)
def labels(self):
return self.call_procedure("db.labels", read_only=True).result_set
def relationshipTypes(self):
return self.call_procedure("db.relationshipTypes", read_only=True).result_set
def propertyKeys(self):
return self.call_procedure("db.propertyKeys", read_only=True).result_set
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