diff --git a/data/helpers.d/config b/data/helpers.d/config
index 7a2ccde46..d12316996 100644
--- a/data/helpers.d/config
+++ b/data/helpers.d/config
@@ -1,6 +1,154 @@
 #!/bin/bash
 
 
+_ynh_app_config_get_one() {
+    local short_setting="$1"
+    local type="$2"
+    local bind="$3"
+    local getter="get__${short_setting}"
+    # Get value from getter if exists
+    if type -t $getter 2>/dev/null | grep -q '^function$' 2>/dev/null;
+    then
+        old[$short_setting]="$($getter)"
+        formats[${short_setting}]="yaml"
+
+    elif [[ "$bind" == *"("* ]] && type -t "get__${bind%%(*}" 2>/dev/null | grep -q '^function$' 2>/dev/null;
+    then
+        old[$short_setting]="$("get__${bind%%(*}" $short_setting $type $bind)"
+        formats[${short_setting}]="yaml"
+    
+    elif [[ "$bind" == "null" ]]
+    then
+        old[$short_setting]="YNH_NULL"
+
+    # Get value from app settings or from another file
+    elif [[ "$type" == "file" ]]
+    then
+        if [[ "$bind" == "settings" ]]
+        then
+            ynh_die --message="File '${short_setting}' can't be stored in settings"
+        fi
+        old[$short_setting]="$(ls "$(echo $bind | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)" 2> /dev/null || echo YNH_NULL)"
+        file_hash[$short_setting]="true"
+
+    # Get multiline text from settings or from a full file
+    elif [[ "$type" == "text" ]]
+    then
+        if [[ "$bind" == "settings" ]]
+        then
+            old[$short_setting]="$(ynh_app_setting_get $app $short_setting)"
+        elif [[ "$bind" == *":"* ]]
+        then
+            ynh_die --message="For technical reasons, multiline text '${short_setting}' can't be stored automatically  in a variable file, you have to create custom getter/setter"
+        else
+            old[$short_setting]="$(cat $(echo $bind | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/) 2> /dev/null || echo YNH_NULL)"
+        fi
+
+    # Get value from a kind of key/value file
+    else
+        local bind_after=""
+        if [[ "$bind" == "settings" ]]
+        then
+            bind=":/etc/yunohost/apps/$app/settings.yml"
+        fi
+        local bind_key="$(echo "$bind" | cut -d: -f1)"
+        bind_key=${bind_key:-$short_setting}
+        if [[ "$bind_key" == *">"* ]];
+        then
+            bind_after="$(echo "${bind_key}" | cut -d'>' -f1)"
+            bind_key="$(echo "${bind_key}" | cut -d'>' -f2)"
+        fi
+        local bind_file="$(echo "$bind" | cut -d: -f2 | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
+        old[$short_setting]="$(ynh_read_var_in_file --file="${bind_file}" --key="${bind_key}" --after="${bind_after}")"
+
+    fi
+}
+_ynh_app_config_apply_one() {
+    local short_setting="$1"
+    local setter="set__${short_setting}"
+    local bind="${binds[$short_setting]}"
+    local type="${types[$short_setting]}"
+    if [ "${changed[$short_setting]}" == "true" ]
+    then
+        # Apply setter if exists
+        if type -t $setter 2>/dev/null | grep -q '^function$' 2>/dev/null;
+        then
+            $setter
+
+        elif [[ "$bind" == *"("* ]] && type -t "set__${bind%%(*}" 2>/dev/null | grep -q '^function$' 2>/dev/null;
+        then
+            "set__${bind%%(*}" $short_setting $type $bind
+    
+        elif [[ "$bind" == "null" ]]
+        then
+            continue
+
+        # Save in a file
+        elif [[ "$type" == "file" ]]
+        then
+            if [[ "$bind" == "settings" ]]
+            then
+                ynh_die --message="File '${short_setting}' can't be stored in settings"
+            fi
+            local bind_file="$(echo "$bind" | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
+            if [[ "${!short_setting}" == "" ]]
+            then
+                ynh_backup_if_checksum_is_different --file="$bind_file"
+                ynh_secure_remove --file="$bind_file"
+                ynh_delete_file_checksum --file="$bind_file" --update_only
+                ynh_print_info --message="File '$bind_file' removed"
+            else
+                ynh_backup_if_checksum_is_different --file="$bind_file"
+                if [[ "${!short_setting}" != "$bind_file" ]]
+                then
+                    cp "${!short_setting}" "$bind_file"
+                fi
+                ynh_store_file_checksum --file="$bind_file" --update_only
+                ynh_print_info --message="File '$bind_file' overwrited with ${!short_setting}"
+            fi
+
+        # Save value in app settings
+        elif [[ "$bind" == "settings" ]]
+        then
+            ynh_app_setting_set --app=$app --key=$short_setting --value="${!short_setting}"
+            ynh_print_info --message="Configuration key '$short_setting' edited in app settings"
+
+        # Save multiline text in a file
+        elif [[ "$type" == "text" ]]
+        then
+            if [[ "$bind" == *":"* ]]
+            then
+                ynh_die --message="For technical reasons, multiline text '${short_setting}' can't be stored automatically  in a variable file, you have to create custom getter/setter"
+            fi
+            local bind_file="$(echo "$bind" | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
+            ynh_backup_if_checksum_is_different --file="$bind_file"
+            echo "${!short_setting}" > "$bind_file"
+            ynh_store_file_checksum --file="$bind_file" --update_only
+            ynh_print_info --message="File '$bind_file' overwrited with the content you provieded in '${short_setting}' question"
+
+        # Set value into a kind of key/value file
+        else
+            local bind_after=""
+            local bind_key="$(echo "$bind" | cut -d: -f1)"
+            bind_key=${bind_key:-$short_setting}
+            if [[ "$bind_key" == *">"* ]];
+            then
+                bind_after="$(echo "${bind_key}" | cut -d'>' -f1)"
+                bind_key="$(echo "${bind_key}" | cut -d'>' -f2)"
+            fi
+            local bind_file="$(echo "$bind" | cut -d: -f2 | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
+
+            ynh_backup_if_checksum_is_different --file="$bind_file"
+            ynh_write_var_in_file --file="${bind_file}" --key="${bind_key}" --value="${!short_setting}" --after="${bind_after}"
+            ynh_store_file_checksum --file="$bind_file" --update_only
+
+            # We stored the info in settings in order to be able to upgrade the app
+            ynh_app_setting_set --app=$app --key=$short_setting --value="${!short_setting}"
+            ynh_print_info --message="Configuration key '$bind_key' edited into $bind_file"
+
+        fi
+    fi
+}
 _ynh_app_config_get() {
     # From settings
     local lines
@@ -29,62 +177,11 @@ EOL
     do
         # Split line into short_setting, type and bind
         IFS=';' read short_setting type bind <<< "$line"
-        local getter="get__${short_setting}"
         binds[${short_setting}]="$bind"
         types[${short_setting}]="$type"
         file_hash[${short_setting}]=""
         formats[${short_setting}]=""
-        # Get value from getter if exists
-        if type -t $getter 2>/dev/null | grep -q '^function$' 2>/dev/null;
-        then
-            old[$short_setting]="$($getter)"
-            formats[${short_setting}]="yaml"
-
-        elif [[ "$bind" == "null" ]]
-        then
-            old[$short_setting]="YNH_NULL"
-
-        # Get value from app settings or from another file
-        elif [[ "$type" == "file" ]]
-        then
-            if [[ "$bind" == "settings" ]]
-            then
-                ynh_die --message="File '${short_setting}' can't be stored in settings"
-            fi
-            old[$short_setting]="$(ls "$(echo $bind | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)" 2> /dev/null || echo YNH_NULL)"
-            file_hash[$short_setting]="true"
-
-        # Get multiline text from settings or from a full file
-        elif [[ "$type" == "text" ]]
-        then
-            if [[ "$bind" == "settings" ]]
-            then
-                old[$short_setting]="$(ynh_app_setting_get $app $short_setting)"
-            elif [[ "$bind" == *":"* ]]
-            then
-                ynh_die --message="For technical reasons, multiline text '${short_setting}' can't be stored automatically  in a variable file, you have to create custom getter/setter"
-            else
-                old[$short_setting]="$(cat $(echo $bind | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/) 2> /dev/null || echo YNH_NULL)"
-            fi
-
-        # Get value from a kind of key/value file
-        else
-            local bind_after=""
-            if [[ "$bind" == "settings" ]]
-            then
-                bind=":/etc/yunohost/apps/$app/settings.yml"
-            fi
-            local bind_key="$(echo "$bind" | cut -d: -f1)"
-            bind_key=${bind_key:-$short_setting}
-            if [[ "$bind_key" == *">"* ]];
-            then
-                bind_after="$(echo "${bind_key}" | cut -d'>' -f1)"
-                bind_key="$(echo "${bind_key}" | cut -d'>' -f2)"
-            fi
-            local bind_file="$(echo "$bind" | cut -d: -f2 | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
-            old[$short_setting]="$(ynh_read_var_in_file --file="${bind_file}" --key="${bind_key}" --after="${bind_after}")"
-
-        fi
+        ynh_app_config_get_one $short_setting $type $bind
     done
 
 
@@ -93,85 +190,7 @@ EOL
 _ynh_app_config_apply() {
     for short_setting in "${!old[@]}"
     do
-        local setter="set__${short_setting}"
-        local bind="${binds[$short_setting]}"
-        local type="${types[$short_setting]}"
-        if [ "${changed[$short_setting]}" == "true" ]
-        then
-            # Apply setter if exists
-            if type -t $setter 2>/dev/null | grep -q '^function$' 2>/dev/null;
-            then
-                $setter
-
-            elif [[ "$bind" == "null" ]]
-            then
-                continue
-
-            # Save in a file
-            elif [[ "$type" == "file" ]]
-            then
-                if [[ "$bind" == "settings" ]]
-                then
-                    ynh_die --message="File '${short_setting}' can't be stored in settings"
-                fi
-                local bind_file="$(echo "$bind" | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
-                if [[ "${!short_setting}" == "" ]]
-                then
-                    ynh_backup_if_checksum_is_different --file="$bind_file"
-                    ynh_secure_remove --file="$bind_file"
-                    ynh_delete_file_checksum --file="$bind_file" --update_only
-                    ynh_print_info --message="File '$bind_file' removed"
-                else
-                    ynh_backup_if_checksum_is_different --file="$bind_file"
-                    if [[ "${!short_setting}" != "$bind_file" ]]
-                    then
-                        cp "${!short_setting}" "$bind_file"
-                    fi
-                    ynh_store_file_checksum --file="$bind_file" --update_only
-                    ynh_print_info --message="File '$bind_file' overwrited with ${!short_setting}"
-                fi
-
-            # Save value in app settings
-            elif [[ "$bind" == "settings" ]]
-            then
-                ynh_app_setting_set --app=$app --key=$short_setting --value="${!short_setting}"
-                ynh_print_info --message="Configuration key '$short_setting' edited in app settings"
-
-            # Save multiline text in a file
-            elif [[ "$type" == "text" ]]
-            then
-                if [[ "$bind" == *":"* ]]
-                then
-                    ynh_die --message="For technical reasons, multiline text '${short_setting}' can't be stored automatically  in a variable file, you have to create custom getter/setter"
-                fi
-                local bind_file="$(echo "$bind" | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
-                ynh_backup_if_checksum_is_different --file="$bind_file"
-                echo "${!short_setting}" > "$bind_file"
-                ynh_store_file_checksum --file="$bind_file" --update_only
-                ynh_print_info --message="File '$bind_file' overwrited with the content you provieded in '${short_setting}' question"
-
-            # Set value into a kind of key/value file
-            else
-                local bind_after=""
-                local bind_key="$(echo "$bind" | cut -d: -f1)"
-                bind_key=${bind_key:-$short_setting}
-                if [[ "$bind_key" == *">"* ]];
-                then
-                    bind_after="$(echo "${bind_key}" | cut -d'>' -f1)"
-                    bind_key="$(echo "${bind_key}" | cut -d'>' -f2)"
-                fi
-                local bind_file="$(echo "$bind" | cut -d: -f2 | sed s@__FINALPATH__@$final_path@ | sed s/__APP__/$app/)"
-
-                ynh_backup_if_checksum_is_different --file="$bind_file"
-                ynh_write_var_in_file --file="${bind_file}" --key="${bind_key}" --value="${!short_setting}" --after="${bind_after}"
-                ynh_store_file_checksum --file="$bind_file" --update_only
-
-                # We stored the info in settings in order to be able to upgrade the app
-                ynh_app_setting_set --app=$app --key=$short_setting --value="${!short_setting}"
-                ynh_print_info --message="Configuration key '$bind_key' edited into $bind_file"
-
-            fi
-        fi
+        ynh_app_config_apply_one $short_setting
     done
 }
 
@@ -253,6 +272,9 @@ _ynh_app_config_validate() {
         if type -t validate__$short_setting | grep -q '^function$' 2>/dev/null;
         then
             result="$(validate__$short_setting)"
+        elif [[ "$bind" == *"("* ]] && type -t "validate__${bind%%(*}" 2>/dev/null | grep -q '^function$' 2>/dev/null;
+        then
+            "validate__${bind%%(*}" $short_setting
         fi
         if [ -n "$result" ]
         then
@@ -283,6 +305,10 @@ _ynh_app_config_validate() {
 
 }
 
+ynh_app_config_get_one() {
+    _ynh_app_config_get_one $1 $2 $3
+}
+
 ynh_app_config_get() {
     _ynh_app_config_get
 }
@@ -295,6 +321,9 @@ ynh_app_config_validate() {
     _ynh_app_config_validate
 }
 
+ynh_app_config_apply_one() {
+    _ynh_app_config_apply_one $1
+}
 ynh_app_config_apply() {
     _ynh_app_config_apply
 }