Merge pull request #81 from plotly/prevent_initial_call

Prevent initial call

Author: waralex

src/app/callbacks.jl

@@ -1,11 +1,11 @@
 dependency_id_string(id::NamedTuple) = sorted_json(id)
 dependency_id_string(id::String) = sorted_json(id)
 
-function dependency_string(dep::Dependency{Trait, String}) where {Trait} 
+function dependency_string(dep::Dependency{Trait, String}) where {Trait}
     return "$(dep.id).$(dep.property)"
 end
 
-function dependency_string(dep::Dependency{Trait, <:NamedTuple}) where {Trait} 
+function dependency_string(dep::Dependency{Trait, <:NamedTuple}) where {Trait}
     id_str = replace(
         sorted_json(dep.id),
         "."=>"\\."
@@ -33,7 +33,7 @@ end
         state::Union{Vector{State}, State} = []
         )
 
-Create a callback that updates the output by calling function `func`. 
+Create a callback that updates the output by calling function `func`.
 
 # Examples
 
@@ -59,9 +59,10 @@ function callback!(func::Union{Function, ClientsideFunction, String},
      app::DashApp,
      output::Union{Vector{<:Output}, Output},
      input::Union{Vector{<:Input}, Input},
-     state::Union{Vector{<:State}, State} = State[]
+     state::Union{Vector{<:State}, State} = State[];
+     prevent_initial_call = nothing
      )
-     return _callback!(func, app, CallbackDeps(output, input, state))
+     return _callback!(func, app, CallbackDeps(output, input, state), prevent_initial_call = prevent_initial_call)
 end
 
 """
@@ -70,7 +71,7 @@ end
         deps...
         )
 
-Create a callback that updates the output by calling function `func`. 
+Create a callback that updates the output by calling function `func`.
 "Flat" version of `callback!` function, `deps` must be ``Output..., Input...[,State...]``
 
 # Examples
@@ -85,7 +86,7 @@ app = dash() do
 
     end
 end
-callback!(app, 
+callback!(app,
     Output("outputID2", "children"),
     Output("outputID", "children"),
     Input("graphTitle", "value"),
@@ -97,13 +98,14 @@ end
 """
 function callback!(func::Union{Function, ClientsideFunction, String},
      app::DashApp,
-     deps::Dependency...
+     deps::Dependency...;
+     prevent_initial_call = nothing
      )
      output = Output[]
      input = Input[]
      state = State[]
      _process_callback_args(deps, (output, input, state))
-     return _callback!(func, app, CallbackDeps(output, input, state, length(output) > 1))
+     return _callback!(func, app, CallbackDeps(output, input, state, length(output) > 1), prevent_initial_call = prevent_initial_call)
 end
 
 function _process_callback_args(args::Tuple{T, Vararg}, dest::Tuple{Vector{T}, Vararg}) where {T}
@@ -115,20 +117,29 @@ end
 function _process_callback_args(args::Tuple, dest::Tuple{Vector{T}, Vararg}) where {T}
     _process_callback_args(args, Base.tail(dest))
 end
-function _process_callback_args(args::Tuple, dest::Tuple{}) 
+function _process_callback_args(args::Tuple, dest::Tuple{})
     error("The callback method must received first all Outputs, then all Inputs, then all States")
 end
-function _process_callback_args(args::Tuple{}, dest::Tuple{}) 
+function _process_callback_args(args::Tuple{}, dest::Tuple{})
 end
 
 
-function _callback!(func::Union{Function, ClientsideFunction, String}, app::DashApp, deps::CallbackDeps)    
-    
+function _callback!(func::Union{Function, ClientsideFunction, String}, app::DashApp, deps::CallbackDeps; prevent_initial_call)
+
     check_callback(func, app, deps)
-    
+
     out_symbol = Symbol(output_string(deps))
-    callback_func = make_callback_func!(app, func, deps)      
-    push!(app.callbacks, out_symbol => Callback(callback_func, deps))
+    callback_func = make_callback_func!(app, func, deps)
+    push!(
+        app.callbacks,
+        out_symbol => Callback(
+                callback_func,
+                deps,
+                isnothing(prevent_initial_call) ?
+                    get_setting(app, :prevent_initial_callbacks) :
+                    prevent_initial_call
+            )
+        )
 end
 
 

src/app/config.jl

@@ -6,11 +6,12 @@ struct DashConfig
     routes_pathname_prefix ::String
     assets_folder ::String
     assets_url_path ::String
-    assets_ignore ::String    
+    assets_ignore ::String
     serve_locally ::Bool
     suppress_callback_exceptions ::Bool
+    prevent_initial_callbacks ::Bool
     eager_loading ::Bool
-    meta_tags ::Vector{Dict{String, String}} 
+    meta_tags ::Vector{Dict{String, String}}
     assets_external_path ::Union{String, Nothing}
     include_assets_files ::Bool
     show_undo_redo ::Bool

src/app/dashapp.jl

@@ -265,6 +265,15 @@ If a parameter can be set by an environment variable, that is listed as:
         if your layout is dynamic, to bypass these checks.
         env: `DASH_SUPPRESS_CALLBACK_EXCEPTIONS`
 
+- `prevent_initial_callbacks::Bool`: Default ``false``: Sets the default value
+        of ``prevent_initial_call`` for all callbacks added to the app.
+        Normally all callbacks are fired when the associated outputs are first
+        added to the page. You can disable this for individual callbacks by
+        setting ``prevent_initial_call`` in their definitions, or set it
+        ``true`` here in which case you must explicitly set it ``false`` for
+        those callbacks you wish to have an initial call. This setting has no
+        effect on triggering callbacks when their inputs change later on.
+
 - `show_undo_redo::Bool`: Default ``false``, set to ``true`` to enable undo
         and redo buttons for stepping through the history of the app state.
 
@@ -283,6 +292,7 @@ function dash(;
         assets_ignore = "",
         serve_locally = true,
         suppress_callback_exceptions = dash_env(Bool, "suppress_callback_exceptions", false),
+        prevent_initial_callbacks = false,
         eager_loading = false,
         meta_tags = Dict{Symbol, String}[],
         index_string = default_index,
@@ -307,6 +317,7 @@ function dash(;
             assets_ignore,
             serve_locally,
             suppress_callback_exceptions,
+            prevent_initial_callbacks,
             eager_loading,
             meta_tags,
             assets_external_path,

src/app/supporttypes.jl

@@ -22,9 +22,9 @@ struct Dependency{Trait, IdT <: Union{String, NamedTuple}}
 end
 
 dep_id_string(dep::Dependency{Trait, String}) where {Trait} = dep.id
-dep_id_string(dep::Dependency{Trait, <:NamedTuple}) where {Trait} = sorted_json(dep.id)    
+dep_id_string(dep::Dependency{Trait, <:NamedTuple}) where {Trait} = sorted_json(dep.id)
 
-dependency_tuple(dep::Dependency) = (id = dep_id_string(dep), property = dep.property)    
+dependency_tuple(dep::Dependency) = (id = dep_id_string(dep), property = dep.property)
 
 const Input = Dependency{TraitInput}
 const State = Dependency{TraitState}
@@ -37,7 +37,7 @@ We use "==" to denote two deps that refer to the same prop on
 the same component. In the case of wildcard deps, this means
 the same prop on *at least one* of the same components.
 """
-function Base.:(==)(a::Dependency, b::Dependency) 
+function Base.:(==)(a::Dependency, b::Dependency)
     (a.property == b.property) && is_id_matches(a, b)
 end
 
@@ -59,7 +59,7 @@ end
 is_id_matches(a::Dependency{Trait1, String}, b::Dependency{Trait2, String}) where {Trait1, Trait2} = a.id == b.id
 is_id_matches(a::Dependency{Trait1, String}, b::Dependency{Trait2, <:NamedTuple}) where {Trait1, Trait2} = false
 is_id_matches(a::Dependency{Trait1, <:NamedTuple}, b::Dependency{Trait2, String}) where {Trait1, Trait2} = false
-function is_id_matches(a::Dependency{Trait1, <:NamedTuple}, b::Dependency{Trait2, <:NamedTuple}) where {Trait1, Trait2} 
+function is_id_matches(a::Dependency{Trait1, <:NamedTuple}, b::Dependency{Trait2, <:NamedTuple}) where {Trait1, Trait2}
     (Set(keys(a.id)) != Set(keys(b.id))) && return false
 
     for key in keys(a.id)
@@ -70,12 +70,12 @@ function is_id_matches(a::Dependency{Trait1, <:NamedTuple}, b::Dependency{Trait2
 
         a_wild = is_wild(a_value)
         b_wild = is_wild(b_value)
-        
+
         (!a_wild && !b_wild) && return false #Both not wild
-        !(a_wild && b_wild) && continue #One wild, one not 
+        !(a_wild && b_wild) && continue #One wild, one not
         ((a_value == ALL) || (b_value == ALL)) && continue #at least one is ALL
         ((a_value == MATCH) || (b_value == MATCH)) && return false #one is MATCH and one is ALLSMALLER
-        
+
     end
     return true
 end
@@ -100,6 +100,7 @@ end
 struct Callback
     func ::Union{Function, ClientsideFunction}
     dependencies ::CallbackDeps
+    prevent_initial_call ::Bool
 end
 
 is_multi_out(cb::Callback) = cb.dependencies.multi_out == true
@@ -108,7 +109,7 @@ get_output(cb::Callback, i) = cb.dependencies.output[i]
 first_output(cb::Callback) = first(cb.dependencies.output)
 
 struct PreventUpdate <: Exception
-    
+
 end
 
 

src/handler/state.jl

@@ -23,10 +23,12 @@ _dep_clientside_func(func::ClientsideFunction) = func
 _dep_clientside_func(func) = nothing
 function _dependencies_json(app::DashApp)
     result = map(values(app.callbacks)) do callback
-        (inputs = dependency_tuple.(callback.dependencies.input),
-        state = dependency_tuple.(callback.dependencies.state),
-        output = output_string(callback.dependencies),
-        clientside_function = _dep_clientside_func(callback.func)
+        (
+            inputs = dependency_tuple.(callback.dependencies.input),
+            state = dependency_tuple.(callback.dependencies.state),
+            output = output_string(callback.dependencies),
+            clientside_function = _dep_clientside_func(callback.func),
+            prevent_initial_call = callback.prevent_initial_call
         )
     end
     return JSON2.write(result)
@@ -52,7 +54,7 @@ make_reload_state(app::DashApp) = get_devsetting(app, :hot_reload) ? StateReload
 get_cache(state::HandlerState) = state.cache
 
 function rebuild_cache!(state::HandlerState)
-    cache = get_cache(state) 
+    cache = get_cache(state)
     (cache.resources, cache.index_string, cache.dependencies_json) = _cache_tuple(state.app, state.registry)
     cache.need_recache = false
 end