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entity.aggregate
aggregateclj
(aggregate data & opts)Aggregate from a (possibly empty) data structure to the target entity reference. Provides for the common cases of structure building.
The structure root is always a map. Non-unique keys result in a vector whose entries are themselves maps. The key of a vector result is always supplied by the caller as the option :set-name By default instances are held as their unqualified type name or any alias that was defined in the declaration.
- data : the structure being built. Must be a map and always the root even in successive calls to this function.
- opts : options as follows: :from <path> a vector path to the thing being aggregated from. This is only absent when seeding the structure with its initial value (or vector of values, in the case of a non-unique key). When passing through a vector in the structure indicate this using '>' :to <type-ref> mandatory - the type being joined in the structure. :key-val when :from is present, by default it will be used as the value for the target type's :primary key, however this behaviour is overridden by key-val, which may be either the return value of make-key or a vector tuple of [key-name key-value], a keyword identifying a known key or a function (see below). :instance-name the map key to use when placing single instances in the structure. This applies whether the key being applied is unique or not. The name will be used in all map children housing each instance. Optional and if absent the unqualified name or any alias is used. :set-name the map key for the vector returned by non-unique keys when placed in the parent map. Mandatory when a non-unique key is being used, otherwise ignored. :merge Any existing value will always be replaced by a new one. In the case of a non-unique key, an existing vector will be replaced unless this option specifies either :primary or a function. The option of :primary will merge current and new values into the result vector by the primary key set. A function must accept three arguments, the instance-name, current and new vectors, and return a vector containing the required merge. :must-join If true, when aggregating to a vector, the map child will be removed for any instances that don't join with the target. Otherwise the vector entry remains with a nil child where there is no join. :for-each A function called after the aggregation. Will be passed the parent node :read-f The dispatching value for the read-fn multimethod. By default entity.core/read-entity will be called, If key-val is a function it must accept three arguments. These are
- parent : the parent node in the structure
- from : the value being aggregated from
- f-opts : a map containing :key <key-name>, :key-val, :entity <the type being joined>, :set-name and :instance-name
Aggregate from a (possibly empty) data structure to the
target entity reference. Provides for the common cases of
structure building.
The structure root is always a map. Non-unique keys result in
a vector whose entries are themselves maps. The key of a vector
result is always supplied by the caller as the option :set-name
By default instances are held as their unqualified type name or any
alias that was defined in the declaration.
- data : the structure being built. Must be a map and always the
root even in successive calls to this function.
- opts : options as follows:
:from <path> a vector path to the thing being aggregated from.
This is only absent when seeding the structure
with its initial value (or vector of values, in the
case of a non-unique key). When passing through
a vector in the structure indicate this using '>'
:to <type-ref> mandatory - the type being joined in the structure.
:key-val when :from is present, by default it will be used
as the value for the target type's :primary key, however
this behaviour is overridden by key-val, which may
be either the return value of make-key or a vector tuple
of [key-name key-value], a keyword identifying a
known key or a function (see below).
:instance-name the map key to use when placing single instances in the
structure. This applies whether the key being applied
is unique or not. The name will be used in all
map children housing each instance. Optional and if
absent the unqualified name or any alias is used.
:set-name the map key for the vector returned by non-unique keys
when placed in the parent map. Mandatory when a non-unique
key is being used, otherwise ignored.
:merge Any existing value will always be replaced by a new one.
In the case of a non-unique key, an existing vector
will be replaced unless this option specifies
either :primary or a function. The option of :primary
will merge current and new values into the result
vector by the primary key set. A function must accept
three arguments, the instance-name, current and new
vectors, and return a vector containing the required merge.
:must-join If true, when aggregating to a vector, the map child will
be removed for any instances that don't join with the
target. Otherwise the vector entry remains with a
nil child where there is no join.
:for-each A function called after the aggregation. Will be passed
the parent node
:read-f The dispatching value for the read-fn multimethod. By default
entity.core/read-entity will be called,
If key-val is a function it must accept three arguments. These are
- parent : the parent node in the structure
- from : the value being aggregated from
- f-opts : a map containing :key <key-name>, :key-val,
:entity <the type being joined>,
:set-name and :instance-namecljdoc is a website building & hosting documentation for Clojure/Script libraries
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