> ## Documentation Index > Fetch the complete documentation index at: https://partner-help.letsdothis.com/llms.txt > Use this file to discover all available pages before exploring further. # List participants by their answer to a booking form field > Returns confirmed participants whose answer to a booking form field matches the supplied value. Each result includes participant identity details and the matched answer. Specify the field's public ID and an exact `value`, including any surrounding whitespace. Matching uses the public ID stored with each participant's answer. If multiple fields share that public ID, an answer to any of them can match. No matching answers returns an empty list. For example, use a marketing opt-in field and its affirmative answer to find participants who opted in. ## OpenAPI ````yaml /openapi.json get /v0/event-occurrences/{id}/form-field-responses/{publicId} openapi: 3.1.0 info: title: Let's Do This API version: 0.1.0 description: > The full reference — getting started, pagination, error responses, rate limits and the changelog — lives at [partner-help.letsdothis.com/api-reference](https://partner-help.letsdothis.com/api-reference/overview). This page is the interactive OpenAPI view of the same specification. # Authentication Create an API key from **Settings** → **Credentials** in your Let's Do This account and send it as a bearer token: ```bash curl --request GET \ --url "https://api.letsdothis.com/v0/participants" \ --header "Authorization: Bearer YOUR-API-KEY" ``` Keep the key secret: it identifies your organization, so do not ship it in a website or native app. If a key is exposed, revoke it from the same section and create a replacement. # OpenAPI schema Download the [OpenAPI schema](https://api.letsdothis.com/documentation/json) to use with Postman or an OpenAPI client generator. servers: - url: https://api.letsdothis.com description: Production - url: https://api.staging.letsdothis.com description: Staging security: - bearerAuth: [] tags: - name: Events x-group: Events description: Events that participants can register for. - name: EventOccurrences x-group: Event occurrences description: >- Event occurrences scoped to the organizer associated with your Public API credentials. Unlike the public Events catalog, results are limited to your own events. - name: Races x-group: Races description: >- Races within an event occurrence. An event occurrence may have one or more races, for example a 5K and a 10K within the same race day. - name: Tickets x-group: Tickets description: Tickets that are available for events. - name: BookingForms x-group: Booking forms description: >- Booking forms define the questions a booker answers when registering for a ticket. A ticket usually references a single booking form, so expect zero or one, while a booking form may be shared across multiple tickets. - name: BookingFormFields x-group: Booking form fields description: >- Booking form fields are the individual questions on a booking form — their type, label, options, and whether an answer is required. A field can be reused across multiple forms. - name: Bookings x-group: Bookings description: >- Bookings are the transaction record for a registration. A booking may contain one or more participants (entries). - name: Membership x-group: Memberships description: >- Membership schemes, purchased policies and the memberships on them, owned by your organizer. Policies are billing contracts; a membership is one person on a policy. - name: Participant x-group: Participants description: Participants are users who successfully booked an event. - name: LineItem x-group: Line items description: Financial details related to individual items within transactions. - name: AddOns x-group: Add-ons description: >- Organizer-owned products that can be purchased and allocated to participants. Imported products retain stable external identities. - name: DiscountCodes x-group: Discount codes description: >- Discount codes participants enter at checkout to reduce the price of a booking. - name: Credits x-group: Credits description: >- Credits are balances participants can spend at checkout, identified by their email address. - name: Referrals x-group: Referrals description: >- Referral programs, the referrers registered on them, and asynchronous imports of historical referrals. - name: Application x-group: Applications description: >- Applications are created when a user applies for tickets that are set up to require an application process, such as balloted or "Good For Age" entries. - name: Partner x-group: Partners description: >- Partners that were created by the organization who can have Reserved Entries assigned to them. - name: ReservedEntries x-group: Reserved entries description: >- Reserved Entries are entries that are reserved for a partner. After being assigned, the partner can then allocate these entries to participants. - name: Timing x-group: Timing description: >- Timing providers push bib numbers and bib-pack shipments back to Let's Do This for the startlist entries they received. Available to select timing partners only. - name: Identity x-group: API key description: >- What your API key can reach. Available to every key, including scoped ones. paths: /v0/event-occurrences/{id}/form-field-responses/{publicId}: get: tags: - Participant summary: List participants by their answer to a booking form field description: >- Returns confirmed participants whose answer to a booking form field matches the supplied value. Each result includes participant identity details and the matched answer. Specify the field's public ID and an exact `value`, including any surrounding whitespace. Matching uses the public ID stored with each participant's answer. If multiple fields share that public ID, an answer to any of them can match. No matching answers returns an empty list. For example, use a marketing opt-in field and its affirmative answer to find participants who opted in. parameters: - schema: type: - number - 'null' minimum: 1 maximum: 500 example: 100 in: query name: page[size] required: false description: >- The number of entries to return per page. Range between 1 - 500, defaults to 100 - schema: type: - string - 'null' in: query name: page[after] required: false description: Use page.next from the previous response to fetch the next page. - schema: type: - string - 'null' in: query name: page[before] required: false description: Use page.prev from the previous response to fetch the previous page. - schema: type: - string - 'null' enum: - '1' - '-1' - null example: '1' in: query name: sort[updatedAt] required: false description: Sort by update date. 1 for ascending, -1 for descending. - schema: type: - string - 'null' enum: - '1' - '-1' - null example: '1' in: query name: sort[createdAt] required: false description: Sort by creation date. 1 for ascending, -1 for descending. - schema: type: - string - 'null' format: date-time example: '2020-01-01T20:15:00.000Z' in: query name: createdAt[after] required: false description: Only return entries created after this date. - schema: type: - string - 'null' format: date-time example: '2020-01-01T20:15:00.000Z' in: query name: createdAt[before] required: false description: Only return entries created before this date. - schema: type: - string - 'null' format: date-time example: '2020-01-01T20:15:00.000Z' in: query name: updatedAt[after] required: false description: Only return entries updated after this date. - schema: type: - string - 'null' format: date-time example: '2020-01-01T20:15:00.000Z' in: query name: updatedAt[before] required: false description: Only return entries updated before this date. - schema: type: string minLength: 1 example: Opt-in in: query name: value required: true description: >- The exact recorded answer to match, including any surrounding whitespace. Use the stored value or option key, which may differ from the displayed label. Blank values are rejected. - schema: type: string example: '12345678901' in: path name: id required: true description: The ID of the event occurrence to query by. - schema: type: string example: marketingOptIn in: path name: publicId required: true description: >- The public ID the organizer gave the booking form field, as a participant's `fields` report it. responses: '200': description: Default Response content: application/json: schema: $ref: '#/components/schemas/PagedFormFieldRespondents' '400': description: Bad request content: application/json: schema: description: Bad request type: object properties: statusCode: type: number enum: - 400 error: type: string message: type: string '401': description: Unauthorized content: application/json: schema: description: Unauthorized type: object properties: statusCode: type: number enum: - 401 error: type: string message: type: string '403': description: Forbidden content: application/json: schema: description: Forbidden type: object properties: statusCode: type: number enum: - 403 error: type: string message: type: string '404': description: Not found content: application/json: schema: description: Not found type: object properties: statusCode: type: number enum: - 404 error: type: string message: type: string components: schemas: PagedFormFieldRespondents: title: PagedFormFieldRespondents type: object properties: data: type: array items: $ref: '#/components/schemas/FormFieldRespondent' page: type: object properties: totalResults: type: number description: The exact total number of matching participants. prev: type: string description: >- Cursor for the previous page, or an empty string if there is none. next: type: string description: Cursor for the next page, or an empty string if there is none. required: - totalResults - prev - next additionalProperties: false required: - data - page additionalProperties: false description: >- A cursor-paginated list of participants whose answer to one booking form field matched. FormFieldRespondent: title: FormFieldRespondent type: object properties: participantId: type: - string - 'null' description: >- Stable identifier for the participant, as used elsewhere in this API. firstName: type: - string - 'null' lastName: type: - string - 'null' emailAddress: type: - string - 'null' format: email eventOccurrenceId: type: - string - 'null' publicId: type: string description: The public ID of the field that was matched, as you asked for it. fieldName: type: - string - 'null' value: type: string description: The participant's recorded answer. Always the value you filtered on. createdAt: anyOf: - $ref: '#/components/schemas/ISODate' - type: 'null' updatedAt: anyOf: - $ref: '#/components/schemas/ISODate' - type: 'null' required: - participantId - firstName - lastName - emailAddress - eventOccurrenceId - publicId - fieldName - value - createdAt - updatedAt additionalProperties: false description: >- A participant's identity details and matched answer to one booking form field. Other booking form answers are not included. example: participantId: 7d22e97f-b583-4e5b-a2bb-1b927f826a32 firstName: John lastName: Runner emailAddress: john@invalid.test eventOccurrenceId: '21111177561' publicId: marketingOptIn fieldName: Marketing updates value: Opt-in createdAt: '2026-05-12T16:45:00.000Z' updatedAt: '2026-05-12T16:45:03.000Z' ISODate: title: ISODate type: string description: >- Represents a date and time in ISO 8601 format as a string. The string should follow the format `YYYY-MM-DDTHH:mm:ss.sssZ`, where: - `YYYY`: Four-digit year - `MM`: Two-digit month (01-12) - `DD`: Two-digit day of the month (01-31) - `T`: Delimiter indicating the start of the time component - `HH`: Two-digit hour in 24-hour format (00-23) - `mm`: Two-digit minutes (00-59) - `ss.sss`: Seconds with milliseconds (00.000-59.999) - `Z`: UTC timezone designator **Example:** To represent 11:30 AM on May 8th, 2026, the value would be: `"2026-05-08T11:30:00.000Z"`. example: '2026-05-08T11:30:00.000Z' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.