U
    mfH5                     @   s   d Z ddlZddlZddlZddlZddlmZ ddlmZ ddl	m
Z
mZmZ ddlmZ ddlmZ edZed	d
Zdd ZG dd dejZG dd dZG dd dZdddZdd Zdd ZG dd dZdS )z
Various data structures used in query construction.

Factored out from django.db.models.query to avoid making the main module very
large and/or so that they can be used by other modules without getting into
circular import difficulties.
    N)
namedtuple)
FieldError)DEFAULT_DB_ALIASDatabaseErrorconnections)
LOOKUP_SEP)treedjango.db.modelsPathInfozGfrom_opts to_opts target_fields join_field m2m direct filtered_relationc                 c   s&   | V  |   D ]}t|E d H  qd S N)__subclasses__
subclassesclssubclass r   @/tmp/pip-unpacked-wheel-siwebuq3/django/db/models/query_utils.pyr      s    r   c                       s   e Zd ZdZdZdZdZeZdZddd fd	d

Z	dd Z
dd Zdd Zdd Zdd ZdddZdd ZefddZdd Z  ZS )Qze
    Encapsulate filters as objects that can then be combined logically (using
    `&` and `|`).
    ANDORXORTNF)
_connector_negatedc                   s"   t  j|t| ||d d S )N)children	connectornegated)super__init__sorteditems)selfr   r   argskwargs	__class__r   r   r   1   s
    z
Q.__init__c                 C   s   t |ts"t|dddks"t|| sBt|dr8| S t|S t |trl|sl|  \}}}t| ||S t|  }||_|	| | |	|| |S )NconditionalFTcopy)

isinstancer   getattr	TypeErrorhasattrr&   deconstructtyper   add)r    otherconn_r!   r"   objr   r   r   _combine8   s    
z
Q._combinec                 C   s   |  || jS r   )r2   r   r    r.   r   r   r   __or__H   s    zQ.__or__c                 C   s   |  || jS r   )r2   r   r3   r   r   r   __and__K   s    z	Q.__and__c                 C   s   |  || jS r   )r2   r   r3   r   r   r   __xor__N   s    z	Q.__xor__c                 C   s$   t |  }|| | j |  |S r   )r,   r-   r   negate)r    r1   r   r   r   
__invert__Q   s    
zQ.__invert__c                 C   s&   |j | ||ddd\}}|| |S )NF)allow_joinsZ
split_subqZcheck_filterable)Z_add_qZpromote_joins)r    queryr9   reuseZ	summarizeZfor_saveZclauseZjoinsr   r   r   resolve_expressionW   s    

zQ.resolve_expressionc                 c   sH   | V  | j D ]6}t|tr"|d }t|dr<| E dH  q|V  qdS )zg
        Recursively yield this Q object and all subexpressions, in depth-first
        order.
           flattenN)r   r'   tupler*   r>   )r    childr   r   r   r>   f   s    


z	Q.flattenc              
   C   s  ddl m}m} ddlm} ddlm} ddlm} |d}|	 D ]*\}	}
t
|
ds^||
}
|j|
|	dd	 qD||d
d t| jjr|t|| d| d n
||  |j|d}z||dk	W S  tk
r } ztd| | W Y dS d}~X Y nX dS )z|
        Do a database query to check if the expressions of the Q instance
        matches against the expressions.
        r   )BooleanFieldValue)Coalesce)Query)SINGLENr<   F)selectr=   _checkT)output_field)usingz.Got a database error calling check() on %r: %s)Zdjango.db.modelsrA   rB   Zdjango.db.models.functionsrC   Zdjango.db.models.sqlrD   Zdjango.db.models.sql.constantsrE   r   r*   Zadd_annotationr   featuresZsupports_comparing_boolean_exprZadd_qr   Zget_compilerZexecute_sqlr   loggerwarning)r    ZagainstrI   rA   rB   rC   rD   rE   r:   namevaluecompilerer   r   r   checku   s&    

zQ.checkc                 C   sf   d| j j| j jf }|dr*|dd}t| j}i }| j| jkrN| j|d< | j	r\d|d< |||fS )Nz%s.%szdjango.db.models.query_utilsr	   r   Tr   )
r$   
__module____name__
startswithreplacer?   r   r   defaultr   )r    pathr!   r"   r   r   r   r+      s    


zQ.deconstruct)NTNFF)rS   rR   __qualname____doc__r   r   r   rV   r%   r   r2   r4   r5   r6   r8   r<   r>   r   rQ   r+   __classcell__r   r   r#   r   r   $   s*            
r   c                   @   s*   e Zd ZdZdd Zd	ddZdd ZdS )
DeferredAttributez
    A wrapper for a deferred-loading field. When the value is read from this
    object the first time, the query is executed.
    c                 C   s
   || _ d S r   )field)r    r\   r   r   r   r      s    zDeferredAttribute.__init__Nc                 C   sT   |dkr| S |j }| jj}||krL| |}|dkrD|j|gd n|||< || S )zx
        Retrieve and caches the value from the datastore on the first lookup.
        Return the cached value.
        N)fields)__dict__r\   attname_check_parent_chainZrefresh_from_db)r    instancer   data
field_namevalr   r   r   __get__   s    
zDeferredAttribute.__get__c                 C   s6   |j }|| jj}| jjr2| j|kr2t||jS dS )z
        Check if the field value can be fetched from a parent field already
        loaded in the instance. This can be done if the to-be fetched
        field is a primary key field.
        N)_metaZget_ancestor_linkr\   modelprimary_keyr(   r_   )r    ra   optsZ
link_fieldr   r   r   r`      s
    z%DeferredAttribute._check_parent_chain)N)rS   rR   rX   rY   r   re   r`   r   r   r   r   r[      s   
r[   c                   @   st   e Zd Zedd Zeejdddd Zdd Zd	d
 Z	e
dd Zedd ZedddZedddZdS )RegisterLookupMixinc                 C   s   |   |d S r   )get_lookupsget)r   lookup_namer   r   r   _get_lookup   s    zRegisterLookupMixin._get_lookupN)maxsizec                 C   s   dd t | D }| |S )Nc                 S   s   g | ]}|j d i qS )class_lookups)r^   rl   ).0parentr   r   r   
<listcomp>   s    z3RegisterLookupMixin.get_lookups.<locals>.<listcomp>)inspectgetmromerge_dicts)r   rp   r   r   r   rk      s    zRegisterLookupMixin.get_lookupsc                 C   sN   ddl m} | |}|d kr4t| dr4| j|S |d k	rJt||sJd S |S )Nr   )LookuprH   )django.db.models.lookupsrw   rn   r*   rH   
get_lookup
issubclass)r    rm   rw   foundr   r   r   ry      s    
zRegisterLookupMixin.get_lookupc                 C   sN   ddl m} | |}|d kr4t| dr4| j|S |d k	rJt||sJd S |S )Nr   )	TransformrH   )rx   r|   rn   r*   rH   get_transformrz   )r    rm   r|   r{   r   r   r   r}      s    
z!RegisterLookupMixin.get_transformc                 C   s    i }t | D ]}|| q|S )z
        Merge dicts in reverse to preference the order of the original list. e.g.,
        merge_dicts([a, b]) will preference the keys in 'a' over those in 'b'.
        )reversedupdate)Zdictsmergeddr   r   r   rv      s    zRegisterLookupMixin.merge_dictsc                 C   s   t | D ]}|j  qd S r   )r   rk   cache_clearr   r   r   r   _clear_cached_lookups   s    z)RegisterLookupMixin._clear_cached_lookupsc                 C   s4   |d kr|j }d| jkri | _|| j|< |   |S )Nrp   )rm   r^   rp   r   r   lookuprm   r   r   r   register_lookup   s    

z#RegisterLookupMixin.register_lookupc                 C   s"   |dkr|j }| j|= |   dS )zn
        Remove given lookup from cls lookups. For use in tests only as it's
        not thread-safe.
        N)rm   rp   r   r   r   r   r   _unregister_lookup  s    z&RegisterLookupMixin._unregister_lookup)N)N)rS   rR   rX   classmethodrn   	functools	lru_cacherk   ry   r}   staticmethodrv   r   r   r   r   r   r   r   rj      s   






	rj   Fc                 C   s   | j s
dS | j jr|sdS |rD|r2|  |kr2dS |sD| j|krDdS |sR| jrRdS |r| j|kr|r| j|krd| jjj| jf }t	|dS )ap  
    Return True if this field should be used to descend deeper for
    select_related() purposes. Used by both the query construction code
    (compiler.get_related_selections()) and the model instance creation code
    (compiler.klass_info).

    Arguments:
     * field - the field to be checked
     * restricted - a boolean field, indicating if the field list has been
       manually restricted using a requested clause)
     * requested - The select_related() dictionary.
     * load_fields - the set of fields to be loaded on this model
     * reverse - boolean, True if we are checking a reverse select related
    FzXField %s.%s cannot be both deferred and traversed using select_related at the same time.T)
Zremote_fieldZparent_linkZrelated_query_namerM   nullr_   rg   rf   Zobject_namer   )r\   Z
restricted	requestedZload_fieldsreversemsgr   r   r   select_related_descend  s&    

r   c                 C   sV   t dt| d D ]>}t| d| }||kr|| r|| | |d f  S qdS )z
    Check if the lookup_parts contains references to the given annotations set.
    Because the LOOKUP_SEP is contained in the default annotation names, check
    each prefix of the lookup_parts for a match.
    r=   r   N)Fr   )rangelenr   join)Zlookup_partsannotationsnZlevel_n_lookupr   r   r   refs_expression4  s
    r   c                    s,    fdd}||p*t |ddo*||jjS )z
    Check that self.model is compatible with target_opts. Compatibility
    is OK if:
      1) model and opts match (where proxy inheritance is removed)
      2) model is parent of opts' model or the other way around
    c                    s*    j j| jkp(| j j  kp( |  kS r   )rf   Zconcrete_modelZget_parent_list)ri   rg   r   r   rQ   I  s
    
z-check_rel_lookup_compatibility.<locals>.checkrh   F)r(   rg   rf   )rg   Ztarget_optsr\   rQ   r   r   r   check_rel_lookup_compatibilityA  s    r   c                   @   s@   e Zd ZdZe dddZdd Zdd Zd	d
 Zdd Z	dS )FilteredRelationz7Specify custom filtering in the ON clause of SQL joins.	conditionc                C   s:   |st d|| _d | _t|ts*t d|| _g | _d S )Nzrelation_name cannot be empty.z*condition argument must be a Q() instance.)
ValueErrorrelation_namealiasr'   r   r   rW   )r    r   r   r   r   r   r   a  s    
zFilteredRelation.__init__c                 C   s4   t || jstS | j|jko2| j|jko2| j|jkS r   )r'   r$   NotImplementedr   r   r   r3   r   r   r   __eq__k  s    

zFilteredRelation.__eq__c                 C   s,   t | j| jd}| j|_| jd d  |_|S )Nr   )r   r   r   r   rW   )r    cloner   r   r   r   t  s    zFilteredRelation.clonec                 O   s   t ddS )zz
        QuerySet.annotate() only accepts expression-like arguments
        (with a resolve_expression() method).
        z0FilteredRelation.resolve_expression() is unused.N)NotImplementedError)r    r!   r"   r   r   r   r<   z  s    z#FilteredRelation.resolve_expressionc                 C   s&   |j }|j| jt| jd}||S )N)r;   )r:   Zbuild_filtered_relation_qr   setrW   compile)r    rO   
connectionr:   wherer   r   r   as_sql  s    zFilteredRelation.as_sqlN)
rS   rR   rX   rY   r   r   r   r   r<   r   r   r   r   r   r   ^  s   
	r   )F)rY   r&   r   rt   loggingcollectionsr   Zdjango.core.exceptionsr   Z	django.dbr   r   r   Zdjango.db.models.constantsr   Zdjango.utilsr   	getLoggerrK   r
   r   Noder   r[   rj   r   r   r   r   r   r   r   r   <module>   s,   
{)G
%