{"record":{"id":"55511d44e4912b24","repo":"octobercms/october","slug":"model-class-does-not-contain-a-definition-for-55511d","errorCode":null,"errorMessage":"Model ':class' does not contain a definition for ':relation'.","messagePattern":"Model ':class' does not contain a definition for ':relation'\\.","errorType":"exception","errorClass":"ApplicationException","httpStatus":null,"severity":"error","filePath":"modules/backend/widgets/Lists.php","lineNumber":1451,"sourceCode":"        $this->filterCallbacks[] = $filter;\n    }\n\n    //\n    // Helpers\n    //\n\n    /**\n     * isColumnRelated checks if column refers to a relation of the model, with a toggle\n     * switch for checking only relationships with multiple records.\n     */\n    protected function isColumnRelated(ListColumn $column, bool $isMulti = false): bool\n    {\n        if (!$column->relation || $this->isColumnPivot($column)) {\n            return false;\n        }\n\n        if (!$this->model->hasRelation($column->relation)) {\n            throw new ApplicationException(Lang::get(\n                'backend::lang.model.missing_relation',\n                ['class'=>get_class($this->model), 'relation'=>$column->relation]\n            ));\n        }\n\n        if ($isMulti) {\n            return !$this->model->isRelationTypeSingular($column->relation);\n        }\n\n        return true;\n    }\n\n    /**\n     * isColumnPivot checks if a column refers to a pivot model specifically.\n     */\n    protected function isColumnPivot(ListColumn $column): bool\n    {\n        if (!$column->relation || $column->relation !== 'pivot') {","sourceCodeStart":1433,"sourceCodeEnd":1469,"githubUrl":"https://github.com/octobercms/october/blob/b608633a7e8922487d91a8161499020121c3b3bf/modules/backend/widgets/Lists.php#L1433-L1469","documentation":"Error \"Model ':class' does not contain a definition for ':relation'.\" thrown in octobercms/october.","triggerScenarios":"Thrown at modules/backend/widgets/Lists.php:1451 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"b608633a7e8922487d91a8161499020121c3b3bf","analyzedAt":"2026-08-21T04:24:57.515Z","schemaVersion":2},"datasetVersion":"2026-08-21T11:28:35.574Z"}