Filtered query generator

1 files changed, 66 insertions, 0 deletions

diff --git a/:w b/:w
new file mode 100644
index 0000000..d7a5759
--- /dev/null
+++ b/:w
@@ -0,0 +1,66 @@
+package db
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+type DataTable[T any] struct {
+	TableName string
+}
+
+// Filters are stored as KVP where the field is the key and the value is the filter
+func (base *DataTable[T]) formQueryWithFilters(filters map[string]any) string {
+	if len(filters) == 0 {
+		return base.formSelectAllQuery()
+	}
+	var sb = strings.Builder{}
+	var baseQuery = base.formSelectAllQuery()
+	sb.WriteString(strings.TrimRight(baseQuery, ";"))
+	sb.WriteString(" WHERE (")
+	var isFirst = true
+	for k, v := range filters {
+		if !isFirst {
+			sb.WriteString(" AND ")
+		}
+		switch v.(type) {
+		case string:
+			sb.WriteString(fmt.Sprintf("%s = '%s'", k, v))
+		}
+		isFirst = false
+	}
+	sb.WriteString(");")
+	return sb.String()
+}
+
+// Forms a query to get all the fields from database
+func (base *DataTable[T]) formSelectAllQuery() string {
+	var sb = strings.Builder{}
+	sb.WriteString("SELECT (")
+	var fields = base.getFields()
+	for i, v := range fields {
+		if i != 0 {
+			sb.WriteString(", ")
+		}
+		sb.WriteString(v)
+	}
+	sb.WriteString(") FROM ")
+	sb.WriteString(base.TableName)
+	sb.WriteString(";")
+	return sb.String()
+}
+
+func (base *DataTable[T]) getFields() []string {
+	var zero T
+	var outp = make([]string, 0)
+	for _, f := range reflect.VisibleFields(reflect.TypeOf(zero)) {
+		var tag, exists = f.Tag.Lookup("sql")
+		if exists {
+			outp = append(outp, tag)
+		} else {
+			outp = append(outp, f.Name)
+		}
+	}
+	return outp
+}