使用Camel路由读取文件插入MongoDB时遇InvalidPayloadException报错求助

Hey there! Let's break down the org.apache.camel.InvalidPayloadException: No body available of type: com.mongodb.DBObject error you're hitting. This is a common mismatch issue—your file endpoint is reading raw text (or an InputStream) from files, but the MongoDB Camel component expects a body in a format it can serialize to MongoDB documents (like DBObject, Map, POJO, or BsonDocument).

Let's Start with the Root Cause #

By default, Camel's file component returns the file content as a String or InputStream in the message body. The MongoDB component can't directly convert that to a MongoDB document, hence the error. We need to add a step to transform the file content into a compatible type.

Step-by-Step Fixes Based on Your File Format #

1. If Your Files Contain Single JSON Objects

If each file holds a single JSON document (e.g., {"id": 1, "content": "test data"}), use Camel's Jackson JSON component to unmarshal the string into a Map or BasicDBObject:

First, ensure you have the Jackson dependency (Maven example):

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-jackson</artifactId>
  <version>your-camel-version</version>
</dependency>

Then update your route to convert the JSON string:

from("file:/path/to/your/files")
  // Convert JSON string to a Map (MongoDB supports Map directly)
  .unmarshal().json(JsonLibrary.Jackson, Map.class)
  // Or convert to BasicDBObject if you prefer the native MongoDB type
  // .unmarshal().json(JsonLibrary.Jackson, BasicDBObject.class)
  .to("mongodb:mongoConnection?database=yourDb&collection=yourColl&operation=insert");

2. If Your Files Contain Multi-Line JSON (One Document Per Line)

For files with multiple JSON entries (each on a new line), split the file content by lines first, then convert each line:

from("file:/path/to/your/files")
  // Split file content into individual lines
  .split(body().tokenize("\n"))
  // Skip empty lines to avoid errors
  .filter(body().isNotEmpty())
  // Convert each line to a Map
  .unmarshal().json(JsonLibrary.Jackson, Map.class)
  .to("mongodb:mongoConnection?database=yourDb&collection=yourColl&operation=insert");

3. If Your Files Use a Custom Format (e.g., CSV)

For non-JSON formats like CSV, first parse the content into a structured format, then map it to a Map or POJO. Here's an example using Camel's CSV component:

Add the CSV dependency:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-csv</artifactId>
  <version>your-camel-version</version>
</dependency>

Then build the route to parse and transform:

from("file:/path/to/your/files")
  // Parse CSV (configure headers if your file has them)
  .unmarshal().csv().setHeader(Exchange.CSV_HEADER, constant("id,content,createdDate"))
  // Convert parsed rows to Maps
  .process(exchange -> {
      List<Map<String, String>> csvRows = exchange.getIn().getBody(List.class);
      List<Map<String, Object>> mongoDocuments = new ArrayList<>();
      
      for (Map<String, String> row : csvRows) {
          Map<String, Object> doc = new HashMap<>(row);
          // Optional: Convert data types (e.g., string date to LocalDateTime)
          doc.put("createdDate", LocalDateTime.parse(row.get("createdDate")));
          mongoDocuments.add(doc);
      }
      
      exchange.getIn().setBody(mongoDocuments);
  })
  .to("mongodb:mongoConnection?database=yourDb&collection=yourColl&operation=insert");

Additional Debugging Tips #

• Add a log step to verify the body type before and after transformation:

  from("file:/path/to/your/files")
    .log("Original body type: ${body.class} | Content: ${body}")
    .unmarshal().json(JsonLibrary.Jackson, Map.class)
    .log("Transformed body type: ${body.class} | Content: ${body}")
    .to("mongodb:...");
  

• Ensure your Camel and MongoDB component versions are compatible (e.g., use mongodb4 component for MongoDB 4.x+ instead of the older mongodb component).

内容的提问来源于stack exchange，提问作者Shamim Ahmad