Given an existing table, generate code for defining an empty table with the same schema - kdb

Question

I would like to take an existing table that I deserialized from a binary file or obtained from a remote process and generate code that will create an empty copy of the table so that I can have a human-readable representation of the schema that I can use to easily re-create the table.
For example, assume I have a trade table in memory and I want to generate code that will return an empty table of the same schema.
q)show meta trade
c | t f a
-----| -----
time | n
sym | s g
price| f
size | i
stop | b
cond | c
ex | c
I'm aware I can obtain an empty copy of trade by running 0#trade. However, I'd like to have a general function (let's say it's called getSchema) that will behave something like this:
q) getSchema trade
"trade:([]time:`timespan$(); sym:`g#`symbol$(); price:`float$(); size:`int$(); stop:`boolean$(); cond:`char$(); ex:`char$())"
I think it would be straightforward to implement this by processing the result of meta trade, but I was wondering if there was was a more straightforward or publicly available implementation of this function. Thanks.

Answer 1

I haven't seen such function available in public. An example is below, but it does not cover all cases (this is left for an exercise)
getSchema: {
typeMapping: "nsfibc"!("timespan";"symbol";"float";"int";"boolean";"char");
c: exec c from meta x;
t: exec t from meta x;
statement: string[x],":([]";
statement,: "; " sv string[c],'": `",/:(typeMapping#t),\:"$()";
statement,: ")";
statement
};
//Expects table's name as symbol
getSchema`trade
What is not covered:
attributes: Attribute should go in the middle of "; " sv string[c],'": _code_for_attribute_ `",/:(typeMapping#t),\:"$()" statement
types: typeMapping must be enriched to cover the rest of Q types
keys. If table is keyed, then keyed columns are listed inside square brackets t: ([keyed_columns] other_columns)
foreign keys. To be fair they are seldom in use, so I would ignore them

Answer 2

The following should work nicely, however it will only render types atomic types, which will conform to how tables are normally defined. This method just utilizes the string representation of the empty schema that you can achieve via -3!
This should handle keyed tables and attributes but not foreign key.
getSchema:{[x]
/ Render the types with -3!
typs:ssr[-3!value flip 0!0#get x;"\"\"";"`char$()"];
/ Append the column names to the types
colNameType:(string[cols 0!get x],\:":"),'";" vs 1_-1_typs;
/ Ensure the correct keys are shown, add in ;
colnametyp:#[colNameType;count[keys x] - 1;,;"]"],\:";";
/ Combine
raze string[x],":([",(-1_raze colnametyp),")"
}
q)trade:2!([]time:`timespan$(); sym:`g#`symbol$(); price:`float$(); size:`int$(); stop:`boolean$(); cond:`char$(); ex:`char$());
q)getSchema `trade
"trade:([time:`timespan$();sym:`g#`symbol$()];price:`float$();size:`int$();stop:`boolean$();cond:`char$();ex:`char$())"