add new functionality and improve backend server structure

- Enhance server functionality and optimize backend code - Add multi-database support (PostgreSQL, MySQL, SQLite)
2026-03-09 17:36:42 +07:00
parent 4b27b85038
commit f5a985ff1e
526 changed files with 173928 additions and 0 deletions
@@ -0,0 +1,158 @@
+package dbutils
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/pocketbase/dbx"
+)
+
+// TODO: replace json with `jsonb` everywhere in the codebase
+// TODO: Use PostgreSQL's native JSON functions instead of manually simulate JSON functions like SQLite.
+
+// JSONEach returns JSON_EACH SQLite string expression with
+// some normalizations for non-json columns.
+func JSONEach(column string) string {
+	dbType := os.Getenv("DB_TYPE")
+	if dbType == "postgres" {
+		// PostgreSQL:
+		return fmt.Sprintf(
+			`jsonb_array_elements_text(CASE WHEN ([[%s]] IS JSON OR json_valid([[%s]]::text)) AND jsonb_typeof([[%s]]::jsonb) = 'array' THEN [[%s]]::jsonb ELSE jsonb_build_array([[%s]]) END)`,
+			column, column, column, column, column,
+		)
+	}
+
+	if dbType == "mysql" {
+		// MySQL:
+		return fmt.Sprintf(
+			`JSON_TABLE(CASE WHEN JSON_VALID([[%s]]) AND JSON_TYPE([[%s]])='ARRAY' THEN [[%s]] ELSE JSON_ARRAY([[%s]]) END, "$[*]" COLUMNS (value JSON PATH "$"))`,
+			column, column, column, column,
+		)
+	}
+
+	// SQLite (default):
+	return fmt.Sprintf(
+		`json_each(CASE WHEN iif(json_valid([[%s]]), json_type([[%s]])='array', FALSE) THEN [[%s]] ELSE json_array([[%s]]) END)`,
+		column, column, column, column,
+	)
+}
+
+// JSONEachByPlaceholder expands a given user input json array to multiple rows.
+// Use [JSONEach] if you want to expand a column value instead.
+// The [placeholder] is the parameter placeholder in SQL prepared statements.
+// We assume the parameter value is a marshalled JSON array.
+func JSONEachByPlaceholder(placeholder string) string {
+	dbType := os.Getenv("DB_TYPE")
+	if dbType == "postgres" {
+		// PostgreSQL:
+		return fmt.Sprintf(`jsonb_array_elements({:%s}::jsonb)`, placeholder)
+	}
+
+	if dbType == "mysql" {
+		// MySQL:
+		return fmt.Sprintf(`JSON_TABLE({:%s}, "$[*]" COLUMNS (value JSON PATH "$"))`, placeholder)
+	}
+
+	// SQLite (default):
+	return fmt.Sprintf("json_each({:%s})", placeholder)
+}
+
+// JsonArrayExistsStr is used to determine whether a JSON string array contains a string element.
+// Right now it only used to determine whether a JSON string ID array contains a specific ID.
+// Operation "?" definition: Does the string exist as a top-level key within the JSON value?
+// The type of the key is only supported to be string.
+// If we want to support other types, we may need to use `@>` operator instead.
+func JsonArrayExistsStr(column string, strValue string) dbx.Expression {
+	dbType := os.Getenv("DB_TYPE")
+	if dbType == "postgres" {
+		// PostgreSQL:
+		return dbx.NewExp(fmt.Sprintf("[[%s]] ? {:value}::text", column), dbx.Params{
+			"value": strValue,
+		})
+	}
+
+	if dbType == "mysql" {
+		// MySQL:
+		return dbx.NewExp(fmt.Sprintf(
+			"JSON_CONTAINS([[%s]], JSON_ARRAY({:value}))",
+			column,
+		), dbx.Params{"value": strValue})
+	}
+
+	// SQLite (default):
+	return dbx.NewExp(fmt.Sprintf(
+		"EXISTS (SELECT 1 FROM json_each([[%s]]) WHERE value = {:value})",
+		column,
+	), dbx.Params{"value": strValue})
+}
+
+// JSONArrayLength returns JSON_ARRAY_LENGTH SQLite string expression
+// with some normalizations for non-json columns.
+//
+// It works with both json and non-json column values.
+//
+// Returns 0 for empty string or NULL column values.
+func JSONArrayLength(column string) string {
+	dbType := os.Getenv("DB_TYPE")
+	if dbType == "postgres" {
+		// PostgreSQL:
+		return fmt.Sprintf(
+			`(CASE WHEN ([[%s]] IS JSON OR JSON_VALID([[%s]]::text)) AND jsonb_typeof([[%s]]::jsonb) = 'array' THEN jsonb_array_length([[%s]]::jsonb) ELSE 0 END)`,
+			column, column, column, column,
+		)
+	}
+
+	if dbType == "mysql" {
+		// MySQL:
+		return fmt.Sprintf(
+			`(CASE WHEN JSON_VALID([[%s]]) AND JSON_TYPE([[%s]])='ARRAY' THEN JSON_LENGTH([[%s]]) ELSE 0 END)`,
+			column, column, column,
+		)
+	}
+
+	// SQLite (default):
+	return fmt.Sprintf(
+		`json_array_length(CASE WHEN iif(json_valid([[%s]]), json_type([[%s]])='array', FALSE) THEN [[%s]] ELSE (CASE WHEN [[%s]] = '' OR [[%s]] IS NULL THEN json_array() ELSE json_array([[%s]]) END) END)`,
+		column, column, column, column, column, column,
+	)
+}
+
+// JSONExtract returns a JSON_EXTRACT SQLite string expression with
+// some normalizations for non-json columns.
+func JSONExtract(column string, path string) string {
+	// prefix the path with dot if it is not starting with array notation
+	if path != "" && !strings.HasPrefix(path, "[") {
+		path = "." + path
+	}
+
+	dbType := os.Getenv("DB_TYPE")
+	if dbType == "postgres" {
+		// PostgreSQL:
+		return fmt.Sprintf(
+			`JSON_QUERY_OR_NULL([[%s]], '$%s')::jsonb`,
+			column,
+			path,
+		)
+	}
+
+	if dbType == "mysql" {
+		// MySQL:
+		return fmt.Sprintf(
+			`JSON_EXTRACT([[%s]], '$%s')`,
+			column,
+			path,
+		)
+	}
+
+	// SQLite (default):
+	return fmt.Sprintf(
+		// note: the extra object wrapping is needed to workaround the cases where a json_extract is used with non-json columns.
+		"(CASE WHEN json_valid([[%s]]) THEN JSON_EXTRACT([[%s]], '$%s') ELSE JSON_EXTRACT(json_object('pb', [[%s]]), '$.pb%s') END)",
+		column,
+		column,
+		path,
+		column,
+		path,
+	)
+}