Function NewWhereCtx

driver/common/tabletypes.go:204–235

(where string, table *Table)

}

func NewWhereCtx(where string, table *Table) (*WhereContext, error) {
	ast, err := expr.ParseExpression(where)
	if err != nil {
		return nil, err
	} else {
		fields := expr.FindAllIdentityField(ast)
		fieldsMap := make(map[string]int)
		for _, field := range fields {
			escapedFieldName := strings.ToLower(field) // TODO thorough escape
			if escapedFieldName == "true" || escapedFieldName == "false" {
				// qlbridge limitation
			} else if _, ok := fieldsMap[field]; !ok {
				if _, ok := table.OriginalTableColumns.Ordinals[field]; !ok {
					return nil, fmt.Errorf("bad 'where' for table %v.%v: field %v does not exist. known fields: %v",
						table.TableSchema, table.TableName, field, table.OriginalTableColumns.Ordinals)
				} else {
					fieldsMap[field] = table.OriginalTableColumns.Ordinals[field]
				}
			} else {
				// already mapped
			}
		}

		// We parse it even it is just 'true', but use the 'IsDefault' flag to optimize.
		return &WhereContext{
			Where:     where,
			Ast:       ast,
			FieldsMap: fieldsMap,
			IsDefault: strings.ToLower(where) == "true",
		}, nil
	}
}