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Block Helpers In Template Engine

Repeat​

Beeceptor adds an advanced feature known as the Repeat block in the template engine. This allows you to simulate loop constructs while generating mock data. This feature is particularly beneficial when creating a response with JSON arrays, GET API call to retrieve objects or search results in an API response.

Syntax​

{{#repeat count}}
content
{{/repeat}}

Here, the content is the text block to be repeated for the given count times. The argument count has to be a number. A comma will be added between consecutive content blocks.

Examples​

Generating a JSON array of three users objects.

Template used:

[
{{#repeat 3}}
  { 
    "name": "Dave",
    "address": "45 Brookfield",
    "country": "US"
  },
{{/repeat}}
]

Response generated:

[
  { 
    "name": "Dave",
    "address": "45 Brookfield",
    "country": "US"
  },
  { 
    "name": "Dave",
    "address": "45 Brookfield",
    "country": "US"
  },
  { 
    "name": "Dave",
    "address": "45 Brookfield",
    "country": "US"
  }
]

Technical Details​

Here's a detailed technical breakdown of how the Repeat Block functions:

  1. Fixed Iteration Count: By giving a single numerical value as an argument, the repeat block will execute a predetermined number of iterations. This results in consistent output for each request, with the contents of the repeat block duplicated exactly per the specified iteration count.
  2. Random Iteration Range: If you give two numerical values as arguments, it activates a random iteration mode. The system will randomly select a number within this range, leading to a variable number of iterations. Thus, each request generates a unique output as the repeat block's content is replicated a random number of times.
  3. Intelligent Comma Insertion: The repeat block is designed to automatically insert commas (,) between consecutive blocks to ensure the generation of a syntactically correct JSON array or a item list of items. In addtion, it smartly omits the comma after the last block to maintain JSON validity. You can override this behavior by adding comma=false in the repeat argument, which disables the automatic comma insertion. Refer to an example in the table above.
  4. Iteration Cap: The repeat block enforces a maximum limit of 1,000 iterations. If you specify a value exceeding this limit, it is automatically adjusted down to 1,000. This cap ensures efficient performance and avoids excessively large data outputs.
  5. Contextual Keywords: The block supports dynamic keywords such as @index and @total, providing you with contextual information about the current iteration's index and the total iteration count, respectively. This feature is especially useful for labeling or indexing elements within the JSON array output, like assigning unique id fields.

Video Demo​

If & Else​

The if helper in Beeceptor allows you to conditionally emit content in HTTP responses. When you use this helper, Beeceptor evaluates its argument. If the result is false, undefined, null, an empty string (""), zero (0), or an empty array ([]), the block of content associated with this if helper will not be displayed.

Syntax​

{{#if expression}}
content
{{/if}}

Here, the content is the text block will be returned in the HTTP response only when the expression is satisfied. The result of the expression should be non-empty and non-zero to be satisfied. Refer to the examples on how to build expression logic.

You can build complex checks for expression. For instance,

  • to check the presence of a field in a POST request's body, use an expression like (body 'status'). This parses the request body as JSON and evaluates the status field's value.
  • to check the value of a field in the POST request's body, use a sub-expression (eq 'paid' (body 'status')).

Examples​

In the following example, the template checks the order status, and returns additional fields in JSON. You can see a conditional field amountToCollect. When the order status is paid, amountToCollect is set to 0, else it is equal to the order amount.

Template used:

{
    "customerId": "{{body 'customerId'}}",
    "productId": "{{body 'productId'}}",
    "quantity": {{body 'quantity' '1'}},
    "status": "{{body 'status'}}",
    "amount": {{body 'amount'}},
{{#if (eq 'paid' (body 'status'))}}
    "amountToCollect": 0,
{{else}}
    "amountToCollect": {{body 'amount'}},
{{/if}}
}

Payload for the POST request:

{
    "customerId": "1234",
    "productId": "PRODUCTID",
    "quantity": 3,
    "status": "paid",
    "amount": 30
}

Response generated:

{
    "customerId": "1234",
    "productId": "PRODUCTID",
    "quantity": 3,
    "status": "pending",
    "amount": 30,
    "amountToCollect": 0,
}

When the status field in the request body has value paid, the template engine emits "amountToCollect" : 0. Else, the value specified in the amount field is replicated for amountToCollect.

Technical Details​

Here's a detailed technical breakdown of how the Repeat Block functions:

  1. At present the template engine only supports eq operator. The support for more operators will be added soon.
  2. You can pull values from query parameters or request body, in the expression clause.