sqlalchemy.sql.visitors.InternalTraversal

class documentation

class InternalTraversal(util.with_metaclass(_InternalTraversalType, object)):

Known subclasses: sqlalchemy.sql.traversals._CopyInternals, sqlalchemy.sql.traversals._GetChildren, sqlalchemy.sql.traversals.TraversalComparatorStrategy, sqlalchemy.sql.visitors.ExtendedInternalTraversal

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Defines visitor symbols used for internal traversal.

The .InternalTraversal class is used in two ways. One is that it can serve as the superclass for an object that implements the various visit methods of the class. The other is that the symbols themselves of .InternalTraversal are used within the _traverse_internals collection. Such as, the .Case object defines _traverse_internals as

_traverse_internals = [
    ("value", InternalTraversal.dp_clauseelement),
    ("whens", InternalTraversal.dp_clauseelement_tuples),
    ("else_", InternalTraversal.dp_clauseelement),
]

Above, the .Case class indicates its internal state as the attributes named value, whens, and else_. They each link to an .InternalTraversal method which indicates the type of datastructure referred towards.

Using the _traverse_internals structure, objects of type .InternalTraversible will have the following methods automatically implemented:

.Traversible.get_children
.Traversible._copy_internals
.Traversible._gen_cache_key

Subclasses can also implement these methods directly, particularly for the .Traversible._copy_internals method, when special steps are needed.

New in version 1.4.

Method	`dispatch`	Given a method from `.InternalTraversal`, return the corresponding method on a subclass.
Class Variable	`dp_annotations_key`	Visit the _annotations_cache_key element.
Class Variable	`dp_anon_name`	Visit a potentially "anonymized" string value.
Class Variable	`dp_boolean`	Visit a boolean value.
Class Variable	`dp_clauseelement`	Visit a `_expression.ClauseElement` object.
Class Variable	`dp_clauseelement_list`	Visit a list of `_expression.ClauseElement` objects.
Class Variable	`dp_clauseelement_tuple`	Visit a tuple of `_expression.ClauseElement` objects.
Class Variable	`dp_clauseelement_tuples`	Visit a list of tuples which contain `_expression.ClauseElement` objects.
Class Variable	`dp_dialect_options`	Visit a dialect options structure.
Class Variable	`dp_dml_multi_values`	Visit the values() multi-valued list of dictionaries of an `_expression.Insert` object.
Class Variable	`dp_dml_ordered_values`	Visit the values() ordered tuple list of an `_expression.Update` object.
Class Variable	`dp_dml_values`	Visit the values() dictionary of a `.ValuesBase` (e.g. Insert or Update) object.
Class Variable	`dp_fromclause_canonical_column_collection`	Visit a `_expression.FromClause` object in the context of the `columns` attribute.
Class Variable	`dp_fromclause_ordered_set`	Visit an ordered set of `_expression.FromClause` objects.
Class Variable	`dp_has_cache_key`	Visit a `.HasCacheKey` object.
Class Variable	`dp_has_cache_key_list`	Visit a list of `.HasCacheKey` objects.
Class Variable	`dp_named_ddl_element`	Visit a simple named DDL element.
Class Variable	`dp_operator`	Visit an operator.
Class Variable	`dp_plain_dict`	Visit a dictionary with string keys.
Class Variable	`dp_plain_obj`	Visit a plain python object.
Class Variable	`dp_prefix_sequence`	Visit the sequence represented by `_expression.HasPrefixes` or `_expression.HasSuffixes`.
Class Variable	`dp_propagate_attrs`	Visit the propagate attrs dict. This hardcodes to the particular elements we care about right now.
Class Variable	`dp_statement_hint_list`	Visit the `_statement_hints` collection of a `_expression.Select` object.
Class Variable	`dp_string`	Visit a plain string value.
Class Variable	`dp_string_clauseelement_dict`	Visit a dictionary of string keys to `_expression.ClauseElement` objects.
Class Variable	`dp_string_list`	Visit a list of strings.
Class Variable	`dp_string_multi_dict`	Visit a dictionary of string keys to values which may either be plain immutable/hashable or `.HasCacheKey` objects.
Class Variable	`dp_table_hint_list`	Visit the `_hints` collection of a `_expression.Select` object.
Class Variable	`dp_type`	Visit a `.TypeEngine` object
Class Variable	`dp_unknown_structure`	Visit an unknown structure.
Method	`generate_dispatch`	Undocumented
Method	`run_generated_dispatch`	Undocumented
Class Variable	`dp_executable_options`	Undocumented
Class Variable	`dp_memoized_select_entities`	Undocumented
Class Variable	`dp_setup_join_tuple`	Undocumented
Class Variable	`dp_with_context_options`	Undocumented

def dispatch(self, visit_symbol):

Given a method from .InternalTraversal, return the corresponding method on a subclass.

dp_annotations_key =

Visit the _annotations_cache_key element.

This is a dictionary of additional information about a ClauseElement that modifies its role. It should be included when comparing or caching objects, however generating this key is relatively expensive. Visitors should check the "_annotations" dict for non-None first before creating this key.

dp_anon_name =

Visit a potentially "anonymized" string value.

The string value is considered to be significant for cache key generation.

dp_boolean =

Visit a boolean value.

The boolean value is considered to be significant for cache key generation.

dp_clauseelement =

Visit a _expression.ClauseElement object.

dp_clauseelement_list =

Visit a list of _expression.ClauseElement objects.

dp_clauseelement_tuple =

Visit a tuple of _expression.ClauseElement objects.

dp_clauseelement_tuples =

Visit a list of tuples which contain _expression.ClauseElement objects.

dp_dialect_options =

Visit a dialect options structure.

dp_dml_multi_values =

Visit the values() multi-valued list of dictionaries of an _expression.Insert object.

dp_dml_ordered_values =

Visit the values() ordered tuple list of an _expression.Update object.

dp_dml_values =

Visit the values() dictionary of a .ValuesBase (e.g. Insert or Update) object.

dp_fromclause_canonical_column_collection =

Visit a _expression.FromClause object in the context of the columns attribute.

The column collection is "canonical", meaning it is the originally defined location of the .ColumnClause objects. Right now this means that the object being visited is a _expression.TableClause or _schema.Table object only.

dp_fromclause_ordered_set =

Visit an ordered set of _expression.FromClause objects.

dp_has_cache_key =

Visit a .HasCacheKey object.

dp_has_cache_key_list =

Visit a list of .HasCacheKey objects.

dp_named_ddl_element =

Visit a simple named DDL element.

The current object used by this method is the .Sequence.

The object is only considered to be important for cache key generation as far as its name, but not any other aspects of it.

dp_operator =

Visit an operator.

The operator is a function from the sqlalchemy.sql.operators module.

The operator value is considered to be significant for cache key generation.

dp_plain_dict =

Visit a dictionary with string keys.

The keys of the dictionary should be strings, the values should be immutable and hashable. The dictionary is considered to be significant for cache key generation.

dp_plain_obj =

Visit a plain python object.

The value should be immutable and hashable, such as an integer. The value is considered to be significant for cache key generation.

dp_prefix_sequence =

Visit the sequence represented by _expression.HasPrefixes or _expression.HasSuffixes.

dp_propagate_attrs =

Visit the propagate attrs dict. This hardcodes to the particular elements we care about right now.

dp_statement_hint_list =

Visit the _statement_hints collection of a _expression.Select object.

dp_string =

Visit a plain string value.

Examples include table and column names, bound parameter keys, special keywords such as "UNION", "UNION ALL".

The string value is considered to be significant for cache key generation.

dp_string_clauseelement_dict =

Visit a dictionary of string keys to _expression.ClauseElement objects.

dp_string_list =

Visit a list of strings.

dp_string_multi_dict =

Visit a dictionary of string keys to values which may either be plain immutable/hashable or .HasCacheKey objects.

dp_table_hint_list =

Visit the _hints collection of a _expression.Select object.

dp_type =

Visit a .TypeEngine object

The type object is considered to be significant for cache key generation.

dp_unknown_structure =

Visit an unknown structure.

def generate_dispatch(self, target_cls, internal_dispatch, generate_dispatcher_name):

Undocumented

def run_generated_dispatch(self, target, internal_dispatch, generate_dispatcher_name):

Undocumented

dp_executable_options =

Undocumented

dp_memoized_select_entities =

Undocumented

dp_setup_join_tuple =

Undocumented

dp_with_context_options =

Undocumented