fix: allow any value as default value in lookup transforms (#7074)

build/vega-lite-schema.json

@@ -10398,7 +10398,7 @@
       "properties": {
         "filter": {
           "$ref": "#/definitions/PredicateComposition",
-          "description": "The `filter` property must be a predication definition, which can take one of the following forms:\n\n1) an [expression](https://vega.github.io/vega-lite/docs/types.html#expression) string, where `datum` can be used to refer to the current data object. For example, `{filter: \"datum.b2 > 60\"}` would make the output data includes only items that have values in the field `b2` over 60.\n\n2) one of the [field predicates](https://vega.github.io/vega-lite/docs/predicate.html#field-predicate):  [`equal`](https://vega.github.io/vega-lite/docs/predicate.html#field-equal-predicate), [`lt`](https://vega.github.io/vega-lite/docs/predicate.html#lt-predicate), [`lte`](https://vega.github.io/vega-lite/docs/predicate.html#lte-predicate), [`gt`](https://vega.github.io/vega-lite/docs/predicate.html#gt-predicate), [`gte`](https://vega.github.io/vega-lite/docs/predicate.html#gte-predicate), [`range`](https://vega.github.io/vega-lite/docs/predicate.html#range-predicate), [`oneOf`](https://vega.github.io/vega-lite/docs/predicate.html#one-of-predicate), or [`valid`](https://vega.github.io/vega-lite/docs/predicate.html#valid-predicate),\n\n3) a [selection predicate](https://vega.github.io/vega-lite/docs/predicate.html#selection-predicate), which define the names of a selection that the data point should belong to (or a logical composition of selections).\n\n4) a [logical composition](https://vega.github.io/vega-lite/docs/predicate.html#composition) of (1), (2), or (3)."
+          "description": "The `filter` property must be a predication definition, which can take one of the following forms:\n\n1) an [expression](https://vega.github.io/vega-lite/docs/types.html#expression) string, where `datum` can be used to refer to the current data object. For example, `{filter: \"datum.b2 > 60\"}` would make the output data includes only items that have values in the field `b2` over 60.\n\n2) one of the [field predicates](https://vega.github.io/vega-lite/docs/predicate.html#field-predicate): [`equal`](https://vega.github.io/vega-lite/docs/predicate.html#field-equal-predicate), [`lt`](https://vega.github.io/vega-lite/docs/predicate.html#lt-predicate), [`lte`](https://vega.github.io/vega-lite/docs/predicate.html#lte-predicate), [`gt`](https://vega.github.io/vega-lite/docs/predicate.html#gt-predicate), [`gte`](https://vega.github.io/vega-lite/docs/predicate.html#gte-predicate), [`range`](https://vega.github.io/vega-lite/docs/predicate.html#range-predicate), [`oneOf`](https://vega.github.io/vega-lite/docs/predicate.html#one-of-predicate), or [`valid`](https://vega.github.io/vega-lite/docs/predicate.html#valid-predicate),\n\n3) a [selection predicate](https://vega.github.io/vega-lite/docs/predicate.html#selection-predicate), which define the names of a selection that the data point should belong to (or a logical composition of selections).\n\n4) a [logical composition](https://vega.github.io/vega-lite/docs/predicate.html#composition) of (1), (2), or (3)."
         }
       },
       "required": [
@@ -15238,8 +15238,7 @@
           "description": "The output fields on which to store the looked up data values.\n\nFor data lookups, this property may be left blank if `from.fields` has been specified (those field names will be used); if `from.fields` has not been specified, `as` must be a string.\n\nFor selection lookups, this property is optional: if unspecified, looked up values will be stored under a property named for the selection; and if specified, it must correspond to `from.fields`."
         },
         "default": {
-          "description": "The default value to use if lookup fails.\n\n__Default value:__ `null`",
-          "type": "string"
+          "description": "The default value to use if lookup fails.\n\n__Default value:__ `null`"
         },
         "from": {
           "anyOf": [

src/transform.ts

@@ -16,7 +16,7 @@ export interface FilterTransform {
    * where `datum` can be used to refer to the current data object.
    * For example, `{filter: "datum.b2 > 60"}` would make the output data includes only items that have values in the field `b2` over 60.
    *
-   * 2) one of the [field predicates](https://vega.github.io/vega-lite/docs/predicate.html#field-predicate): 
+   * 2) one of the [field predicates](https://vega.github.io/vega-lite/docs/predicate.html#field-predicate):
    * [`equal`](https://vega.github.io/vega-lite/docs/predicate.html#field-equal-predicate),
    * [`lt`](https://vega.github.io/vega-lite/docs/predicate.html#lt-predicate),
    * [`lte`](https://vega.github.io/vega-lite/docs/predicate.html#lte-predicate),
@@ -356,7 +356,7 @@ export interface LookupTransform {
    *
    * __Default value:__ `null`
    */
-  default?: string;
+  default?: any;
 
   /**
    * Data source or selection for secondary data reference.