Cache column names to avoid having to escape them

Author: iamed2

src/results.jl

@@ -18,6 +18,9 @@ mutable struct Result
     "Conversions from PostgreSQL data to Julia types for each column in the result"
     column_funcs::Vector{Base.Callable}
 
+    "Name of each column in the result"
+    column_names::Vector{String}
+
     # TODO: attach encoding per https://wiki.postgresql.org/wiki/Driver_development#Result_object_and_client_encoding
     function Result(
         result::Ptr{libpq_c.PGresult},
@@ -64,6 +67,10 @@ mutable struct Result
             func_lookup[(oid, typ)]
         end)
 
+        jl_result.column_names = map(1:num_columns(jl_result)) do col_num
+            unsafe_string(libpq_c.PQfname(jl_result.result, col_num - 1))
+        end
+
         # figure out which columns the user says may contain nulls
         if not_null isa Bool
             jl_result.not_null = fill(not_null, size(col_types))
@@ -423,27 +430,23 @@ end
 Return the name of the column at index `column_number` (1-based).
 """
 function column_name(jl_result::Result, column_number::Integer)
-    # todo: check cleared?
-    unsafe_string(libpq_c.PQfname(jl_result.result, column_number - 1))
+    return jl_result.column_names[column_number]
 end
 
 """
     column_names(jl_result::Result) -> Vector{String}
 
 Return the names of all the columns in the query result.
 """
-function column_names(jl_result::Result)
-    return [column_name(jl_result, i) for i in 1:num_columns(jl_result)]
-end
+column_names(jl_result::Result) = copy(jl_result.column_names)
 
 """
     column_number(jl_result::Result, column_name::Union{AbstractString, Symbol}) -> Int
 
 Return the index (1-based) of the column named `column_name`.
 """
 function column_number(jl_result::Result, column_name::Union{AbstractString, Symbol})::Int
-    # todo: check cleared?
-    return libpq_c.PQfnumber(jl_result.result, String(column_name)) + 1
+    return something(findfirst(isequal(String(column_name)), jl_result.column_names), 0)
 end
 
 """

test/runtests.jl

@@ -843,6 +843,24 @@ end
             close(conn)
         end
 
+        @testset "Uppercase Columns" begin
+            conn = LibPQ.Connection("dbname=postgres user=$DATABASE_USER"; throw_error=true)
+
+            result = execute(conn, "SELECT 1 AS \"Column\";")
+            @test num_columns(result) == 1
+            @test LibPQ.column_name(result, 1) == "Column"
+            @test LibPQ.column_number(result, :Column) == 1
+
+            table = Tables.columntable(result)
+            @test hasproperty(table, :Column)
+
+            table = Tables.rowtable(result)
+            @test hasproperty(table[1], :Column)
+
+            close(result)
+            close(conn)
+        end
+
         @testset "PQResultError" begin
             conn = LibPQ.Connection("dbname=postgres user=$DATABASE_USER"; throw_error=true)