dtrans 
Data transformation and validation micro library. Not production ready. Breaking changes is coming
Take a wow-effect from coverage
$ rebar3 ct --cover && rebar3 cover --verboseShort documentation
Field properties
Internal
Association internal => true means that this field be constructed
without input data using only functions with /0 arity and other
from fields values throught tuple:
{depends_on, [other_field_name], fun(OtherFieldValue) -> {ok, 42} end}
Note: lambda-function above will be called with validated and constructed values
Warning: when this property is set as
true-required,validator,default_valuebeing ignored
1> {ok, Model} = dtrans:new(#{
timestamp =>
#{internal => true,
constructor =>
fun() ->
{ok, erlang:apply(erlang, timestamp, [])}
end
}
}).
2> dtrans:extract(#{}, Model).
{ok,#{timestamp => {1545,494367,679728}}}Note: default value of this property is
false
Required
Correctly set required field give the opportunity checks model
while building in future this will be used in compile-time models
checks
1> dtrans:new(#{
a =>
#{required => false,
default_value => 0
},
b =>
#{required => false,
default_value => 0
},
sum_of_a_and_b =>
#{internal => true,
required => true,
constructor =>
{depends_on,
[a, b],
fun(A, B) -> {ok, A + B} end}
}
}).
{error,dependency_tree_model_cannot_be_resolved}And this field property using while data extracting
1> {ok, Model} = dtrans:new(#{
required_field =>
#{required => true}
}).
2> dtrans:extract(#{}, Model).
{error,{no_data,required_field}}Note: default value of this property is
false
Validator
This field may be set validation lambda-function with /1 arity.
This function should be return ok or {error, Reason :: any()} values
1> {ok, Model} = dtrans:new(#{
invalid_field =>
#{validator =>
fun
(42 = _Value) -> ok;
(_Value) -> {error, "Expected value is 42"}
end
}
}).
2> dtrans:extract(#{invalid_field => 43}, Model).
{error,{validation_error,invalid_field,"Expected value is 42"}}Note: default value of this property is constant
ok
Default value
Default value working only for required => false not internal fields
1> {ok, Model} = dtrans:new(#{
field =>
#{default_value => 0}
}).
2> dtrans:extract(#{}, Model).
{ok,#{field => 0}}
3> dtrans:extract(#{field => 42}, Model).
{ok,#{field => 42}}1> {ok, Model} = dtrans:new(#{
field => #{}
}).
2> dtrans:extract(#{}, Model).
{ok,#{}}
3> dtrans:extract(#{field => 42}, Model).
{ok,#{field => 42}}Constructor
You can change final value of field throught set property constructor by lambda function with /1 arity
or tuple for using other fields values:
{depends_on, [other_field_name], fun(MainFieldValue, OtherFieldValue) -> {ok, 42} end}
Construction functions must be returns {ok, Value :: any()} or {error, Reason :: any()} values
Note: lambda-function above will be called with validated and constructed values
Warning: by using
depends_onyou may be show{error, {cyclic_dependency, [...]} while building model
1> {ok, Model} = dtrans:new(#{
field =>
#{constructor =>
fun(Value) ->
{ok, Value + 41}
end
}
}).
2> dtrans:extract(#{field => 1}, Model).
{ok,#{field => 42}}Note: default value of this property is identity function
Model
With model property you can inherit model in other model as field specification
1> {ok, InnerModel} = dtrans:new(#{
inner_field => #{}
}).
2> {ok, OuterModel} = dtrans:new(#{
outer_field =>
#{required => true,
model => InnerModel
}
}).
3> dtrans:extract(#{outer_field => #{inner_field => 4}}, OuterModel).
{ok, #{outer_field => #{inner_field => 4}}}Count
While count property is set to one lists will be processing as one
object, while is set to many lists processiong as list of models and
validation/extraction will be called on each element
1> {ok, Model} = dtrans:new(#{
field =>
#{count => many,
constructor => fun(Value) -> {ok, Value + 1} end
}
})
2> dtrans:extract(#{field => [1, 2, 3]}, Model).
{ok,#{field => [2,3,4]}}Note: default value of this property is
one
TODO
- Add compile-time build for models where possible
- Add more information to errors
-
Use other model as field spec
-
New model field property
model - New model field property set count of models
-
New model field property
