#64 fix display precision of big numbers

Project.toml

@@ -1,6 +1,6 @@
 name = "TableView"
 uuid = "40c74d1a-b44c-5b06-a7c1-6cbea58ea978"
-version = "0.6.4"
+version = "0.6.5"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"

src/TableView.jl

@@ -7,6 +7,7 @@ using Observables: @map
 export showtable
 
 const ag_grid_imports = []
+const js_max_safe_int = Int128(2^53-1)
 
 function __init__()
     version = readchomp(joinpath(@__DIR__, "..", "ag-grid.version"))
@@ -252,32 +253,28 @@ end
 # directly write JSON instead of allocating temporary dicts etc
 function table2json(schema, rows, types; requested = nothing)
     io = IOBuffer()
-    print(io, '[')
+    rowwriter = JSON.Writer.CompactContext(io)
+    JSON.begin_array(rowwriter)
+    ser = JSON.StandardSerialization()
     for (i, row) in enumerate(rows)
-        if requested == nothing || first(requested) <= i <= last(requested)
-            print(io, '{')
-            Tables.eachcolumn(schema, row) do val, ind, name
-                JSON.print(io, name)
-                print(io, ':')
-                if val isa Number && isfinite(val)
-                    JSON.print(io, val)
-                elseif val === nothing
-                    JSON.print(io, repr(nothing))
-                elseif val === missing
-                    JSON.print(io, repr(missing))
-                else
-                    JSON.print(io, sprint(print, val))
-                end
-                print(io, ',')
+        if requested != nothing && (i < first(requested) || i > last(requested))
+            continue
+        end
+        JSON.delimit(rowwriter)
+        columnwriter = JSON.Writer.CompactContext(io)
+        JSON.begin_object(columnwriter)
+        Tables.eachcolumn(schema, row) do val, ind, name
+            if val isa Real && isfinite(val) && -js_max_safe_int < trunc(Int128, val) < js_max_safe_int
+                JSON.show_pair(columnwriter, ser, name, val)
+            elseif val === nothing || val === missing
+                JSON.show_pair(columnwriter, ser, name, repr(val))
+            else
+                JSON.show_pair(columnwriter, ser, name, sprint(print, val))
             end
-            skip(io, -1)
-            print(io, '}')
-            print(io, ',')
         end
+        JSON.end_object(columnwriter)
     end
-    skip(io, -1)
-    print(io, ']')
-
+    JSON.end_array(rowwriter)
     String(take!(io))
 end
 end

test/runtests.jl

@@ -32,6 +32,16 @@ end
     @test firstrow["d"] == 0
     @test firstrow["e"] == "test_missing"
 end
+@testset "large integers" begin
+    rows = Tables.table([2^52 2^53 2^54])
+    names = [:a, :b, :c]
+    types = [Int64 for _ in 1:3]
+    json = TableView.table2json(Tables.Schema(names, types), rows, types)
+    firstrow = JSON.parse(json)[1]
+    @test firstrow["a"] == 4503599627370496
+    @test firstrow["b"] == "9007199254740992"
+    @test firstrow["c"] == "18014398509481984"
+end
 @testset "normal array" begin
     array = rand(10, 10)
     @test showtable(array) isa WebIO.Scope