Improve string support for reporter expressions

store/rdbms/ast_transformer.go

@@ -127,6 +127,14 @@ var (
 			Handler: makeGenericCompHandler("/"),
 		},
 
+		// - strings
+		"concat": {
+			Args:    collectParams(true, "String"),
+			RArgs:   true,
+			Result:  wrapRes("String"),
+			Handler: makeGenericFncHandler("CONCAT"),
+		},
+
 		// @todo better negation?
 		"like": {
 			Args:    collectParams(true, "String", "String"),
@@ -240,6 +248,13 @@ var (
 			Result:  wrapRes("Float"),
 			Handler: makeGenericTypecastHandler("SIGNED"),
 		},
+		// @todo some better way of casting to string?
+		//       MySQL does not support casting to longtext so I decided on doing this for now
+		"string": {
+			Args:    collectParams(true, "Any"),
+			Result:  wrapRes("String"),
+			Handler: makeGenericTypecastHandler("CHAR(8192)"),
+		},
 	}
 )
 

store/rdbms/ast_transformer_handlers.go

@@ -131,6 +131,21 @@ func makeGenericAggFncHandler(fnc string) HandlerSig {
 	}
 }
 
+func makeGenericFncHandler(fnc string) HandlerSig {
+	return func(aa ...FormattedASTArgs) (out string, args []interface{}, selfEnclosed bool, err error) {
+		selfEnclosed = true
+
+		params := make([]string, len(aa))
+		for i, a := range aa {
+			params[i] = a.S
+			args = append(args, a.Args...)
+		}
+
+		out = fmt.Sprintf("%s(%s)", fnc, strings.Join(params, ", "))
+		return
+	}
+}
+
 func makeGenericTypecastHandler(t string) HandlerSig {
 	return func(aa ...FormattedASTArgs) (out string, args []interface{}, selfEnclosed bool, err error) {
 		selfEnclosed = true

store/sqlite3/sql_functions.go

@@ -63,6 +63,20 @@ var (
 			return
 		},
 
+		// - strings
+		"concat": func(aa ...rdbms.FormattedASTArgs) (out string, args []interface{}, selfEnclosed bool, err error) {
+			selfEnclosed = true
+
+			params := make([]string, len(aa))
+			for i, a := range aa {
+				params[i] = a.S
+				args = append(args, a.Args...)
+			}
+
+			out = fmt.Sprintf("(%s)", strings.Join(params, "||"))
+			return
+		},
+
 		// - typecast
 		"float": func(aa ...rdbms.FormattedASTArgs) (out string, args []interface{}, selfEnclosed bool, err error) {
 			selfEnclosed = true
@@ -76,6 +90,18 @@ var (
 			args = aa[0].Args
 			return
 		},
+		"string": func(aa ...rdbms.FormattedASTArgs) (out string, args []interface{}, selfEnclosed bool, err error) {
+			selfEnclosed = true
+
+			if len(aa) != 1 {
+				err = fmt.Errorf("expecting 1 argument, got %d", len(aa))
+				return
+			}
+
+			out = fmt.Sprintf("CAST(%s AS TEXT)", aa[0].S)
+			args = aa[0].Args
+			return
+		},
 	}
 )
 

tests/reporter/group_date_composition_test.go

@@ -0,0 +1,27 @@
+package reporter
+
+import (
+	"testing"
+
+	"github.com/cortezaproject/corteza-server/pkg/report"
+)
+
+func Test_group_date_composition(t *testing.T) {
+	var (
+		ctx, h, s = setup(t)
+		m, _, dd  = loadScenario(ctx, s, t, h)
+		ff        []*report.Frame
+		def       = dd[0]
+	)
+
+	ff = loadNoErr(ctx, h, m, def)
+	h.a.Len(ff, 1)
+	r := ff[0]
+	h.a.Equal(2, r.Size())
+
+	h.a.Equal("by_dob<String>, count<Number>", r.Columns.String())
+
+	checkRows(h, ff[0],
+		"2020-01, 5",
+		"2021-01, 7")
+}

tests/reporter/testdata/group_date_composition/report.json

@@ -0,0 +1,38 @@
+{
+  "handle": "testing_report",
+  "sources": [
+    { "step": { "load": {
+      "name": "users",
+      "source": "composeRecords",
+      "definition": {
+        "module": "user",
+        "namespace": "ns"
+      }
+    }}},
+
+    { "step": { "group": {
+      "name": "grouped",
+      "source": "users",
+      "keys": [
+        { "name": "by_dob", "def": "concat(string(year(dob)), '-', string(month(dob)))" }
+      ],
+      "columns": [
+        {
+          "name": "count",
+          "def": {
+            "ref": "count"
+          }
+        }
+      ]
+    }}}
+  ],
+  "frames": [{
+    "name":   "result",
+    "source": "grouped",
+    "columns": [
+      { "name": "by_dob", "label": "by_dob" },
+      { "name": "count", "label": "count" }
+    ],
+    "sort": "by_dob ASC"
+  }]
+}