alibaba/spring-ai-alibaba · warning

变量替换失败，使用原始模板: template={}, variables={}

Error message

变量替换失败，使用原始模板: template={}, variables={}

What it means

ModelConfigParser.replaceVariables substitutes {{placeholder}} variables into a prompt template using a variables JSON string; if any step throws (malformed JSON, bad types, null values), it logs this warning and returns the raw template with unreplaced placeholders. The prompt is sent to the model containing literal {{variable}} tokens.

Source

Thrown at spring-ai-alibaba-admin/spring-ai-alibaba-admin-server-start/src/main/java/com/alibaba/cloud/ai/studio/admin/utils/ModelConfigParser.java:177

            return template;
        }
        
        try {
            JsonNode variables = objectMapper.readTree(variablesJson);
            StringBuilder resultBuilder = new StringBuilder(template);
            
            // 替换所有变量占位符
            variables.fields().forEachRemaining(entry -> {
                String placeholder = "{{" + entry.getKey() + "}}";
                String value = entry.getValue().asText();
                String current = resultBuilder.toString();
                resultBuilder.setLength(0);
                resultBuilder.append(current.replace(placeholder, value));
            });
            
            return resultBuilder.toString();
        } catch (Exception e) {
            log.warn("变量替换失败，使用原始模板: template={}, variables={}", template, variablesJson, e);
            return template;
        }
    }
    
    /**
     * 验证模型配置的有效性 只验证必需字段，动态参数由模型服务自行验证
     *
     * @param modelConfigInfo 模型配置信息
     * @throws IllegalArgumentException 如果配置无效
     */
    public void validateModelConfig(ModelConfigInfo modelConfigInfo) {
        if (modelConfigInfo == null) {
            throw new IllegalArgumentException("模型配置不能为空");
        }
        
        if (modelConfigInfo.getModelId() == null) {
            throw new IllegalArgumentException("模型ID不能为空");
        }

View on GitHub (pinned to f82da0b50f)

Solutions

1. Validate variablesJson parses to a JSON object (JSONObject.parseObject) before calling replaceVariables
2. Escape or remove literal {{...}} sequences in templates that are not variables
3. Check the variable names in the template exactly match the JSON keys
4. If a raw template with placeholders is unacceptable downstream, throw instead of returning the template

Example fix

// before
String prompt = ModelConfigParser.replaceVariables(tpl, "a=1;b=2"); // invalid JSON, raw template returned
// after
String prompt = ModelConfigParser.replaceVariables(tpl, "{\"a\":\"1\",\"b\":\"2\"}");
if (prompt.contains("{{")) { throw new IllegalArgumentException("Unresolved variables in prompt"); }

try { JSONObject.parseObject(variablesJson); } catch (Exception e) { throw new IllegalArgumentException("variables must be a JSON object"); }

boolean isValidVariablesJson(String s) { try { JSONObject.parseObject(s); return true; } catch (Exception e) { return false; } }

String prompt = ModelConfigParser.replaceVariables(tpl, varsJson); if (prompt.contains("{{")) { throw new IllegalStateException("Unresolved template variables"); }

When it happens

Trigger: Passing a variablesJson that is invalid JSON (or non-object), or a template referencing placeholders with values of types the replacement cannot stringify, throwing inside the replacement lambda chain.

Common situations: Client sends variables as a comma-separated string instead of JSON object; nested/escaped quotes break JSON parsing; variable name mismatch leaving placeholders; template containing literal {{ }} syntax that was never meant as a variable.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• WORKFLOW_EXECUTE_ERROR
• CreateMCPServerError
• UpdateMCPServerError
• INVALID_PARAMS
• INVALID_PARAMS

AI-assisted analysis of alibaba/spring-ai-alibaba@f82da0b50f (2026-09-09). Data as JSON: /api/errors/fb3455223cda3c21. Report an issue: GitHub.