dql.expressions.selection module

Selection expressions

class dql.expressions.selection.AttributeSelection(expr1, op=None, expr2=None)

Bases: dql.expressions.base.Expression

A tree of select expressions

build(self, visitor)

Build string expression, using the visitor to encode values

evaluate(self, item)

Evaluate this expression for a partiular item

classmethod from_statement(cls, statement)

Factory for creating a Attribute expression

class dql.expressions.selection.NamedExpression(expr, alias=None)

Bases: dql.expressions.base.Expression

Wrapper around AttributeSelection that holds the alias (if any)

build(self, visitor)

Build string expression, using the visitor to encode values

classmethod from_statement(cls, statement)

Parse the selection expression and alias from a statement

key

The name that this will occupy in the final result dict

populate(self, item, ret, sanitize)

Evaluate the child expression and put result into return value

class dql.expressions.selection.NowFunction(utc)

Bases: dql.expressions.selection.SelectFunction

Function to grab the current time

build(self, visitor)

Build string expression, using the visitor to encode values

evaluate(self, item)

classmethod from_statement(cls, statement)

class dql.expressions.selection.SelectFunction

Bases: dql.expressions.base.Expression

Base class for special select functions

evaluate(self, item)

Evaluate this expression for a partiular item

classmethod from_statement(cls, statement)

Create a selection function from a statement

class dql.expressions.selection.SelectionExpression(expressions, is_count=False)

Bases: dql.expressions.base.Expression

Entry point for Selection expressions

all_fields

A set of all fields that are required by this statement

all_keys

The keys, in order, that are selected by the statement

build(self, visitor)

Build string expression, using the visitor to encode values

convert(self, item, sanitize=False)

Convert an item into an OrderedDict with the selected fields

classmethod from_selection(cls, selection)

Factory for creating a Selection expression

class dql.expressions.selection.TimestampFunction(expr, utc)

Bases: dql.expressions.selection.SelectFunction

Function that parses a field or literal as a datetime

build(self, visitor)

Build string expression, using the visitor to encode values

evaluate(self, item)

classmethod from_statement(cls, statement)

dql.expressions.selection.add(a, b)

Add two values, ignoring None

dql.expressions.selection.div(a, b)

Divide two values, ignoring None

dql.expressions.selection.mul(a, b)

Multiply two values, ignoring None

dql.expressions.selection.parse_expression(clause)

For a clause that could be a field, value, or expression

dql.expressions.selection.sub(a, b)

Subtract two values, ignoring None